15.1: Differential and integrated rate laws
The rate law of a chemical reaction is an equation that links the initial rate with the concentrations (or pressures) of the reactants. Rate laws usually include a constant parameter, \(k\), called the rate coefficient , and several parameters found at the exponent of the concentrations of the reactants, and are called reaction orders . The rate coefficient depends on several conditions, including the reaction type, the temperature, the surface area of an adsorbent, light irradiation, and others. The reaction rate is usually represented with the lowercase letter \(k\), and it should not be confused with the thermodynamic equilibrium constant that is generally designated with the uppercase letter \(K\). Another useful concept in kinetics is the half-life, usually abbreviated with \(t_{1/2}\). The half-life is defined as the time required to reach half of the initial reactant concentration.
A reaction that happens in one single microscopic step is called elementary. Elementary reactions have reaction orders equal to the (integer) stoichiometric coefficients for each reactant. As such, only a limited number of elementary reactions are possible (four types are commonly observed), and they are classified according to their overall reaction order. The global reaction order of a reaction is calculated as the sum of each reactant’s individual orders and is, at most, equal to three. We examine in detail the four most common reaction orders below.
Zeroth-order reaction
For a zeroth-order reaction, the reaction rate is independent of the concentration of a reactant. In other words, if we have a reaction of the type:
\[ \text{A}\longrightarrow\text{products} \nonumber \]
the differential rate law can be written:
\[ - \dfrac{d[\mathrm{A}]}{dt}=k_0 [\mathrm{A}]^0 = k_0, \label{15.1.1} \]
which shows that any change in the concentration of \(\mathrm{A}\) will have no effect on the speed of the reaction. The minus sign at the right-hand-side is required because the rate is always defined as a positive quantity, while the derivative is negative because the concentration of the reactant is diminishing with time. Separating the variables \([\mathrm{A}]\) and \(t\) of Equation \ref{15.1.1} and integrating both sides, we obtain the integrated rate law for a zeroth-order reaction as:
\[ \begin{equation} \begin{aligned} \int_{[\mathrm{A}]_0}^{[A]} d[\mathrm{A}] &= -k_0 \int_{t=0}^{t} dt \\ [\mathrm{A}]-[\mathrm{A}]_0 &= -k_0 t \\ \\ [\mathrm{A}]&=[\mathrm{A}]_0 -k_0 t. \end{aligned} \end{equation} \label{15.1.2} \]
Using the integrated rate law, we notice that the concentration on the reactant diminishes linearly with respect to time. A plot of \([\mathrm{A}]\) as a function of \(t\), therefore, will result in a straight line with an angular coefficient equal to \(-k_0\), as in the plot of Figure \(\PageIndex{1}\).
Eq. (15.1.2) also suggests that the units of the rate coefficient for a zeroth-order reaction are of concentration divided by time, typically \(\dfrac{\mathrm{M}}{\mathrm{s}}\), with \(\mathrm{M}\) being the molar concentration in \(\dfrac{\mathrm{mol}}{\mathrm{L}}\) and \(s\) the time in seconds. The half-life of a zero order reaction can be calculated from Equation \ref{15.1.2}, by replacing \([\mathrm{A}]\) with \(\dfrac{1}{2}[\mathrm{A}]_0\):
\[ \begin{equation} \begin{aligned} \dfrac{1}{2}[\mathrm{A}]_0 &=[\mathrm{A}]_0 -k_0 t_{1/2} \\ t_{1/2} &= \dfrac{[\mathrm{A}]_0}{2k_0}. \end{aligned} \end{equation} \label{15.1.3} \]
Zeroth-order reactions are common in several biochemical processes catalyzed by enzymes, such as the oxidation of ethanol to acetaldehyde in the liver by the alcohol dehydrogenase enzyme, which is zero-order in ethanol.
First-order reaction
A first-order reaction depends on the concentration of only one reactant, and is therefore also called a unimolecular reaction . As for the previous case, if we consider a reaction of the type:
\[ \mathrm{A}\rightarrow \text{products} \nonumber \]
the differential rate law for a first-order reaction is:
\[ - \dfrac{d[\mathrm{A}]}{dt}=k_1 [\mathrm{A}]. \label{15.1.4} \]
Following the usual blueprint of separating the variables, and integrating both sides, we obtain the integrated rate law as:
\[ \begin{equation} \begin{aligned} \int_{[\mathrm{A}]_0}^{[A]} \dfrac{d[\mathrm{A}]}{[\mathrm{A}]} &= -k_1 \int_{t=0}^{t} dt \\ \ln \dfrac{[\mathrm{A}]}{[\mathrm{A}]_0}&=-k_1 t\\ \\ [\mathrm{A}] &= [\mathrm{A}]_0 \exp(-k_1 t). \end{aligned} \end{equation} \label{15.1.5} \]
Using the integrated rate law to plot the concentration of the reactant, \([\mathrm{A}]\), as a function of time, \(t\), we obtain an exponential decay, as in Figure \(\PageIndex{2}\).
However, if we plot the logarithm of the concentration, \(\ln[\mathrm{A}]\), as a function of time, we obtain a line with angular coefficient \(-k_1\), as in the plot of Figure \(\PageIndex{3}\). From Equation \ref{15.1.5}, we can also obtain the units for the rate coefficient for a first-order reaction, which typically is \(\dfrac{1}{\mathrm{s}}\), independent of concentration. Since the rate coefficient for first-order reactions has units of inverse time, it is sometimes called the frequency rate.
The half-life of a first-order reaction is:
\[ \begin{equation} \begin{aligned} \ln \dfrac{\dfrac{1}{2}[\mathrm{A}]_0}{[\mathrm{A}]_0}&=-k_1 t_{1/2}\\ t_{1/2} &= \dfrac{\ln 2}{k_1}. \end{aligned} \end{equation} \label{15.1.6} \]
The half-life of a first-order reaction is independent of the initial concentration of the reactant. Therefore, the half-life can be used in place of the rate coefficient to describe the reaction rate. Typical examples of first-order reactions are radioactive decays. For radioactive isotopes, it is common to report their rate of decay in terms of their half-life. For example, the most stable uranium nucleotide, \(^{238}\mathrm{U}\), has a half-life of \(4.468\times 10^9\) years, while the most common fissile isotope of uranium, \(^{235}\mathrm{U}\), has a half-life of \(7.038\times 10^8\) years.\(^1\) Other examples of first-order reactions in chemistry are the class of S N 1 nucleophilic substitution reactions in organic chemistry.
Second-order reaction
A reaction is second-order when the sum of the reaction orders is two. Elementary second-order reactions are also called bimolecular reactions . There are two possibilities, a simple one, where the reaction order of one reagent is two, or a more complicated one, with two reagents having each a reaction order of one.
- For the simple case, we can write the reaction as: \[ 2\mathrm{A}\rightarrow \text{products} \nonumber \] the differential rate law for a first-order reaction is: \[ -\dfrac{d[\mathrm{A}]}{dt}=k_2 [\mathrm{A}]^2. \label{15.1.7} \] Following the same procedure used for the two previous cases, we can obtain the integrated rate law as: \[ \begin{equation} \begin{aligned} \int_{[\mathrm{A}]_0}^{[A]} \dfrac{d[\mathrm{A}]}{[\mathrm{A}]^2} &= -k_2 \int_{t=0}^{t} dt \\ \dfrac{1}{[\mathrm{A}]}-\dfrac{1}{[\mathrm{A}]_0} &= k_2 t\\ \\ \dfrac{1}{[\mathrm{A}]}&=\dfrac{1}{[\mathrm{A}]_0} + k_2 t. \end{aligned} \end{equation} \label{15.1.8} \] As for first-order reactions, the plot of the concentration as a function of time shows a non-linear decay. However, if we plot the inverse of the concentration, \(\dfrac{1}{[\mathrm{A}]}\), as a function of time, \(t\), we obtain a line with angular coefficient \(+k_2\), as in the plot of Figure \(\PageIndex{4}\).
Notice that the line has a positive angular coefficient, in contrast with the previous two cases, for which the angular coefficients were negative. The units of \(k\) for a simple second order reaction are calculated from Equation \ref{15.1.8} and typically are \(\dfrac{1}{\mathrm{M}\cdot \mathrm{s}}\). The half-life of a simple second-order reaction is: \[ \begin{equation} \begin{aligned} \dfrac{1}{\dfrac{1}{2}[\mathrm{A}]_0}-\dfrac{1}{[\mathrm{A}]_0} &= k_2 t_{1/2} \\ t_{1/2} &= \dfrac{1}{k_2 [\mathrm{A}]_0}, \end{aligned} \end{equation} \label{15.1.9} \] which, perhaps not surprisingly, depends on the initial concentration of the reactant, \([\mathrm{A}]_0\). Therefore, if we start with a higher concentration of the reactant, the half-life will be shorter, and the reaction will be faster. An example of simple second-order behavior is the reaction \(\mathrm{NO}_2 + \mathrm{CO} \rightarrow \mathrm{NO} + \mathrm{CO}_2\), which is second-order in \(\mathrm{NO}_2\) and zeroth-order in \(\mathrm{CO}\).
- For the complex second-order case, the reaction is: \[ \mathrm{A}+\mathrm{B}\rightarrow \text{products} \nonumber \] and the differential rate law is: \[ -\dfrac{d[\mathrm{A}]}{dt}=k'_2 [\mathrm{A}][\mathrm{B}]. \label{15.1.10} \] The differential equation in Equation \ref{15.1.10} has two variables, and cannot be solved exactly unless an additional relationship is specified. If we assume that the initial concentration of the two reactants are equal, then \([\mathrm{A}]=[\mathrm{B}]\) at any time \(t\), and Equation \ref{15.1.10} reduces to Equation \ref{15.1.7}. If the concentration of the reactants are different, then the integrated rate law will assume the following shape: \[ \dfrac{\mathrm{[A]}}{\mathrm{[B]}} = \dfrac{\mathrm{[A]_0}}{\mathrm{[B]_0}} \exp \left\{ \left(\mathrm{[A]_0} - \mathrm{[B]_0}\right) k'_2t \right\}. \label{15.1.11} \] The units of \(k\) for a complex second order reaction can be calculated from Equation \ref{15.1.11}, and are the same as those for the simple case, \(\dfrac{1}{\mathrm{M}\cdot \mathrm{s}}\). The half-life of a complex second-order reaction cannot be easily written since two different half-lives could, in principle, be defined for each of the corresponding reactants.
Third and higher orders reaction
Although elementary reactions with order higher than two are possible, they are in practice infrequent, and only very few experimental third-order reactions are observed. Fourth-order or higher have never been observed because the probabilities for a simultaneous interaction between four molecules are essentially zero. Third-order elementary reactions are also called termolelucar reactions . While termolelucar reactions with three identical reactants are possible in principle, there is no known experimental example. Some complex third-order reactions are known, such as:
\[ 2\text{NO}_{(g)}+\text{O}_{2(g)}\longrightarrow 2\text{NO}_{2(g)} \nonumber \]
for which the differential rate law can be written as:
\[ -\dfrac{dP_{\mathrm{O}_2}}{dt}=k_3 P_{\mathrm{NO}}^2 P_{\mathrm{O}_2}. \label{15.1.12} \]
- Notice how large these numbers are for uranium. To put these numbers in perspective, we can compare them with the half-life of the most unstable isotope of plutonium, \(^{241}\mathrm{Pu}\), which is \(t_{1/2}=14.1\) years.


12.1.4: Barriers to Trade
What are the Barriers to International Trade?
International trade is carried out by both businesses and governments—as long as no one puts up trade barriers. In general, trade barriers keep firms from selling to one another in foreign markets. The major obstacles to international trade are natural barriers, tariff barriers, and non-tariff barriers.
Natural Barriers
Natural barriers to trade can be either physical or cultural. For instance, even though raising beef in the relative warmth of Argentina may cost less than raising beef in the bitter cold of Siberia, the cost of shipping the beef from South America to Siberia might drive the price too high. Distance is thus one of the natural barriers to international trade.
Language is another natural trade barrier. People who can’t communicate effectively may not be able to negotiate trade agreements or may ship the wrong goods.
Tariff Barriers
A tariff is a tax imposed by a nation on imported goods. It may be a charge per unit, such as per barrel of oil or per new car; it may be a percentage of the value of the goods, such as 5 percent of a $500,000 shipment of shoes; or it may be a combination. No matter how it is assessed, any tariff makes imported goods more costly, so they are less able to compete with domestic products.
Protective tariffs make imported products less attractive to buyers than domestic products. The United States, for instance, has protective tariffs on imported poultry, textiles, sugar, and some types of steel and clothing, and in March of 2018 the Trump administration added tariffs on steel and aluminum from most countries. On the other side of the world, Japan imposes a tariff on U.S. cigarettes that makes them cost 60 percent more than Japanese brands. U.S. tobacco firms believe they could get as much as a third of the Japanese market if there were no tariffs on cigarettes. With tariffs, they have under 2 percent of the market.
Arguments for and Against Tariffs
Congress has debated the issue of tariffs since 1789. The main arguments for tariffs include the following:
- Tariffs protect infant industries. A tariff can give a struggling new domestic industry time to become an effective global competitor.
- Tariffs protect U.S. jobs. Unions and others say tariffs keep foreign labor from taking away U.S. jobs.
- Tariffs aid in military preparedness. Tariffs should protect industries and technology during peacetime that are vital to the military in the event of war.
The main arguments against tariffs include the following:
- Tariffs discourage free trade, and free trade lets the principle of competitive advantage work most efficiently.
- Tariffs raise prices, thereby decreasing consumers’ purchasing power. In 2017, the United States imposed tariffs of 63.86 percent to 190.71 percent on a wide variety of Chinese steel products. The idea was to give U.S. steel manufacturers a fair market after the Department of Commerce concluded their antidumping and anti-subsidy probes. It is still too early to determine what the effects of these tariffs will be, but higher steel prices are likely. Heavy users of steel, such as construction and automobile industries, will see big increases in their production costs. It is also likely that China may impose tariffs on certain U.S. products and services and that any negotiations on intellectual property and piracy will bog down.
Non-tariff Barriers
Governments also use other tools besides tariffs to restrict trade. One type of non-tariff barrier is the import quota , or limits on the quantity of a certain good that can be imported. The goal of setting quotas is to limit imports to the specific amount of a given product. The United States protects its shrinking textile industry with quotas. A complete list of the commodities and products subject to import quotas is available on line at the U.S. Customs and Border Protection Agency website.
A complete ban against importing or exporting a product is an embargo . Often embargoes are set up for defense purposes. For instance, the United States does not allow various high-tech products, such as supercomputers and lasers, to be exported to countries that are not allies. Although this embargo costs U.S. firms billions of dollars each year in lost sales, it keeps enemies from using the latest technology in their military hardware.
Government rules that give special privileges to domestic manufacturers and retailers are called buy-national regulations . One such regulation in the United States bans the use of foreign steel in constructing U.S. highways. Many state governments have buy-national rules for supplies and services. In a more subtle move, a country may make it hard for foreign products to enter its markets by establishing customs regulations that are different from generally accepted international standards, such as requiring bottles to be quart size rather than liter size.
Exchange controls are laws that require a company earning foreign exchange (foreign currency) from its exports to sell the foreign exchange to a control agency, usually a central bank. For example, assume that Rolex, a Swiss company, sells 300 watches to Zales Jewelers, a U.S. chain, for US$600,000. If Switzerland had exchange controls, Rolex would have to sell its U.S. dollars to the Swiss central bank and would receive Swiss francs. If Rolex wants to buy goods (supplies to make watches) from abroad, it must go to the central bank and buy foreign exchange (currency). By controlling the amount of foreign exchange sold to companies, the government controls the amount of products that can be imported. Limiting imports and encouraging exports helps a government to create a favorable balance of trade.
CONCEPT CHECK
- Discuss the concept of natural trade barriers.
- Describe several tariff and non-tariff barriers to trade.


2.4: The Book of Songs
THE BOOK OF SONGS
Existed before Confucius (born around 551 B.C.E.)
China
The Book of Songs (the Shi king , also translated as The Classic of Poetry and The Book of Odes ) is a collection of poems written by various anonymous authors over several centuries. Traditionally, Confucius has been credited as the editor of the collection, and it was part of the canon of Confucian works that scholars were expected to study. Scholars debate how much influence Confucius may have had on them; one theory is that he took a much larger work (possibly several thousand poems) and chose just over three hundred to form the standard version that exists today. Poetry collections in China were meant to represent the voice of the people (male and female, all social classes). The poems capture moments in time, speaking to the reader about the problems and joys of individuals who were not necessarily the rulers or heroes of other stories.
Written by Laura J. Getty
THE SHI KING, THE OLD "POETRY CLASSIC" OF THE CHINESE [THE BOOK OF SONGS]
License: Public Domain
Translated by William Jennings
BOOK II.: THE ODES OF SHÂU AND THE SOUTH.
The Wedding-Journey of a Princess
The magpie has a nest;
The dove yet takes possession.
—
Lo! the young bride departs,
In many-wheeled procession.
The magpie has a nest;
The dove yet there will quarter.—
Lo! the young bride departs;
And countless cars escort her.
The magpie has a nest;
The dove will fill it (quickly).—
Lo! the young bride departs,
With chariots mustered thickly.
A Reverent Helpmate
There gathers she the fragment herb
Along the islets, by the pools,
To mingle with the votive gifts
Of him that o'er the princedom rules.
There gathers she the fragrant herb
Amid the mountain streams again,
To mingle with the votive gifts
Her prince will offer in the fane.
With head-gear all erect and high
Ere dawn the temple she attends;
With head-gear all uncared for now
Back to her place her way she wends.
A Long-Absent Husband
Now the crickets chirp and grind;
And the hoppers spring and fly.
But my lord not yet I find;
Ay, and sore at heart am I.
O to see him once again!
O to meethim once again!
Stilled were then the swelling sigh.
Climbed I yonder up South Hill.
Plucked sweet brackens as I went.
But my lord I saw not still;
Loud was yet my heart's lament.
O to see him once again!
O to meet him once again!
So my heart were well content.
Climbed I yonder up South Hill,
Now to pluck the royal fern.
Yet my lord I saw not still;
Still my heart must pine and yearn.
O to see him once again!
O to meet him once again!
So my heart's-ease might return.
The Young Wife's Zealous Care in the Worship of her Husband's Ancestors
She goes to gather water-wort,
Beside the streams south of the hills;
She goes to gather water-grass
Along the swollen roadside rills;
Goes now to store her gathered herbs
In basket round, in basket square;
Goes now to seethe and simmer them
In tripod and in cauldron there;
Pours out libations of them all
Beneath the light within the Hall.
—
And who is she—so occupied?
—Who, but (our lord's) young pious bride?
In Memory of a Worthy Chieftain
O pear-tree, with thy leafy shade!
Ne'er be thou cut, ne'er be thou laid;—
Once under thee Shâu's chieftain stayed.
O pear-tree, with thy leafy crest,
Ne'er may they cut thee, ne'er molest;—
Shâu's chief beneath thee once found rest.
O pear-tree, with thy leafy shroud,
Ne'er be those branches cut, nor bowed,
That shelter to Shâu's chief allowed.
The Resisted Suitor
All soaking was the path with dew.
And was it not scarce daybreak, too?
I say: the path was drenched with dew.
Who says the sparrow has no horn?
How bores it then into my dwelling?
Who says of thee, thou art forlorn?
Why then this forcing and compelling?
But force, compel, me, do thy will:
Husband and wife we are not still.
Who says of rats, they have no teeth?
How do they bore then through my wall?
Who says of thee, thou art forlorn?
Why force me then into this brawl?
But force me, sue me,—even so,
With thee I do not mean to go!
Dignity and Economy of King Wăn's Councillors
Clad in lambskin or in sheepskin,
Five white silken seams that show,
To their meal from court retiring,
With what dignity they go!
Bare of wool, the lamb or sheepskin
Five white sutures may reveal,
Still with dignity retire they
From their Master to their meal.
Though the skins, now rent in patches,
Five white silken seams require,
Still with dignity the wearers
To their meal from Court retire.
The Lonely Wife
Hearken! there is thunder
On South Hill's lofty crest.
Hence why must he wander,
Nor dare a moment rest?
True-hearted husband, fain, oh fain
Were I to see thee home again.
Hearken! now the thunder
Rolls lower on South Hill.
Hence why must he wander,
Nor ever dare be still?
True-hearted husband, fain, oh fain
Were I to have thee home again.
Hearken! now the thunder
Is down upon the plain.
Hence why must he wander,
Nor dare awhile remain?
True-hearted husband, fain, oh fain
Were I to find thee home agian.
Fears of Mature Maidenhood
Though shaken be the damnson-tree,
Left on it yet are seven, O.
Ye gentlemen who care for me.
Take chance while chance is given, O.
Though shaken be the damson-tree,
Yet three are still remaining, O.
Ye gentlemen who care for me,
Now, now; the time is waning, O.
Ah, shaken is the damson-tree,
And all are in the basket, O.
Ye gentlemen who care for me,
Your question
—would ye ask it, O!
Contented Concubines
Starlets dim are yonder peeping,—
In the East are five, and three.
Softly, where our lord is (sleeping),
Soon or late by night go we.
Some have high, some low degree.
Starlets dim are yonder peeping,—
Pleiades, Orion's band.
Softly nightly go we creeping,
Quilt and coverlet in hand.
Some take high, some lower stand.
Jealousy Overcome
The Kiang has arms that wayward wind.
Our lady erst as bride
Our help declined,
Our help declined;
—
Anon she was of other mind.
The Kiang has banks within its bed.
Our lady erst as bride
Our presence fled,
Our presence fled;—
Anon a calmer life she led.
The Kiang has creeks that leave it long.
Our lady erst as bride
Spurned all our throng,
Spurned all our throng;—
Her sneering now is turned to song.
The Cunning Hunter
In the wild there lies a dead gazelle,
With the reed-grass round it wrapt;
And a maid who loveth springtide well
By a winsome youth is trapped.
In the wood thick undergrowth is found,
In the wild the dead gazelle,
With the reed-grass round its body bound;
—
And the maid she looketh well.
"Ah! gently, not so fast, good sir;
My kerchief, prithee, do not stir;
Nor rouse the barking of my cur."
A Royal Wedding
What radiant bloom is there!
Blossoms of cherry wild.
What care attends the equipage
Of her, the royal child!
What radiance! Like the bloom
Of peach and plum in one!
Granddaughter of the Just King she,
He a true noble's son.
How was the bait then laid?
'Twas trimmed with silken twine.
He the true noble's son (thus caught)
Her of the Just King's line!
The Tsow Yu
Out there where the reeds grow rank and tall,
One round he shoots, five wild boars fall.
Hail the Tsow Yu!
And there where the grass is waving high,
One round he shoots, five wild hogs die.
Hail the Tsow Yu!
Note. —Although this is one of the shortest and apparently most trivial of the Odes in the Book of Poetry, it is credited by the Chinese editors with as much meaning as the largest. It is regarded, like so many more, as illustrating the extent of the reformation brought about by King Wăn. Not only was the kingdom better ruled, society better regulated, and individuals more self-disciplined and improved in manners, but the reformation affected all things: vegetation flourished, game became most abundant, hunting was attended to at the right seasons, and the benign influence of the King was everywhere felt by the people. The poet thinks it is sufficient to dwell upon these last characteristics. Probably the lines were written after some royal hunt.
BOOK III.: THE ODES OF P'EI.
P'ei was one of three principalities which King Wu created after he overthrew the dynasty of Shang. It was in the north; and the two others were —Yung in the south, and Wei in the west. P'ei and Yung were, after a short time, absorbed in Wei, which had a long history. We have, in Books III., IV. and V. titles taken from all three; but evidently the division is only artificial: the three Books might all have been included probperly under the title Wei, since it is that State with which all are connected.
Derelict
The cedar boat is drifting,
On currents never still.
Sleepless I lie, vexed inly,
As with some unknown ill.
'Tis not that wine is wanting,
Or leave to roam at will.
My heart is no mere mirror
That cannot comprehend.
Brothers I have, but may not
On brothers e'en depend.
Tush! when I go complaining
'Tis only to offend.
No stone this heart of mine is,
That may be turned and rolled;
No mat this heart of mine is,
To fold or to unfold.
Steadfast and strict my life is;
Nought 'gainst it can be told.
Yet here I sit in sorrow,
Scorned by a rabble crew.
My troubles have been many
My insults not a few.
Calmly I think—then, starting,
I beat my breast anew.
O moon, why now the brighter?
O sun, why now dost wane?
My heart wears grief as garments
Inured to soil and stain.
Calmly I think—then, starting,
Would fly—but all in vain.
Supplanted
Green now my robe!
Green, lined with yellow.
Ah! when shall Grief
Be not my fellow!
Green is the robe;
Yellow the skirt!
Ah! when shall Grief
Nevermore hurt!
Green is the silk;
Ruled so by you.—
Guide me, ye ancients!
Harm lest I do.
Lawn, fine or coarse,
Chills in the wind.—
Guide me, ye ancients!
Save me my mind.
Friends In Distress
O the swallows onward flying,
Wings aslant, irregular!
O the lady homeward hieing;
O'er the wilds escort her far.
Gaze I till I gaze in vain,
And my tears are like the rain.
O the swallows onward flying,
Soaring upward, darting low!
O the lady homeward hieing;
Far then let her escort go.
Gaze I till I gaze in vain;
Long I stand and weep amain.
O the swallows onward flying,
High and low, with twittering mouth!
O the lady homeward hieing;
Far escort her to the South.
Gaze I till I gaze in vain,
And my heart scarce bears the pain.
Lady Chung
—on love relying,
And of feelings true and deep,
Ever sweet and much-complying,
Strict, yet, self-respect to keep—
Thoughtful of the dead she:
Bright example to poor me!
Clouds Gathering
O sun, O moon, ye downwards turn
To earth your glorious gaze.
But ah! that men there be like this,
Forsaking ancient ways!
Where can be peace? Alas,
his
glance
From
me
for ever strays!
O sun, O moon, this earth below
Hath you as crown above.
But ah, that men there be like this,
That give not love for love!
Where can be peace? Alas that he
Should so responseless prove!
O sun, O moon, that morn and eve
Rise in yon Eastern sky.
Alas that men there be like this,
Whose deeds fair words belie.
Where can be peace? Ah, better now
If
memory
could but die!
O sun, O moon, that morn and eve
Rise yonder in the East.
O parents mine! your charge of me
Hath not for ever ceased.
Where can be peace? For to my love
responds he not the least.
The Storm
Long, long the stormwind blew, and wild.
—
He turned to look at me: he smiled;
But mockery was there, and scorn.
Ah, how my very heart was torn!
Long, long it blew, with dust for rain.—
"Be kind, and come to me again."
He came not, neither went his way;
And long in pensive thought I lay.
On still it blew, with storm-clouds black;
Scarce light there was, so dense the pack.
Wakeful I lay, nor closed mine eyes;
And anxious thought brought fitful sughs.
Black and more black yet grew the gloom;
Then came loud thunder, boom on boom.
Awake I lay, all sleep was fled,
And anxious thought my fever fed.
The Soldier Sighs For Wife And Home
When the beating of drums was heard around,
How we sprang to our weapons with leap and bound!
But the fields must have some, and the walls of Ts'o;—
We alone to the South must a-marching go.
So we followed our leader Sun Tse-Chung,
And a peace there was made with Ch'in and Sung.
But of homeward march is no sign as yet,
And our hearts are heavy, and pine and fret.
Ah! here we are lingering; here we stay;
And our steeds go wandering far astray;
And quest of them all must needs be made
Away in the depths of the woodland shade.
But, though far to be severed in death or life,
We are bound by the pledge each gave to his wife;
And we vowed, as we stood then hand in hand,
By each other in life's last years to stand.
Alas! now wide is the gulf between!
And life to us now is a blank, I ween.
And, alas, for the plighted troth—so vain!
Untrue to our words we must aye remain.
The Discontented Mother
From the South the gladdening breezes blow
On the heart of that bush of thorn;
And the inmost leaves in it gaily grow.
—
But the mother with care is worn.
From the SOuth the gladdening breezes blow
On the twigs of that thorny tree.
And the mother is wise and good, but oh!
Bad and worthless men are we.
From the spring 'neath the walls of Tsun there runs
A cool and refreshing rill.
But the mother, though hers be seven sons,
Unrelieved here toils on still.
And the golden bright-eyed orioles
Wake their tuneful melodie.
But the mother's heart no son consoles,
Though we seven around her be.
Separation
The male pheasant has taken his flight,
Yet leisurely moved he his wings!
Ah, to thee, my beloved, thyself
What sorrow this severance brings!
The male pheasant has taken his flight;
From below, from aloft, yet he cried.
Ah, true was my lord; and my heart
With its burden of sorrow is tried.
As I gaze at the sun and the moon,
Free rein to my thoughts I allow.
O the way, so they tell me, is long:
Tell me, how can be come to me now?
Wot ye not, then, ye gentlemen all,
Of his virtue and rectitude?
From all envy and enmity free,
What deed doth he other than good?
Untimely Unions
"The leaves of the gourd are yet sour to the taste,
And the way through the ford is deep" (quoth she).
—"Deep be it, our garments we'll raise to the waist,
Or shallow, then up to the knee" (quoth he).
"But the ford is full, and the waters rise.
Hark! a pheasant there, in alarm she cries."
—"Nay, the ford when full would no axle wet;
And the pheasant but cackles to fetch her mate."
"More sweet were the wildgoose' cries to hear,
When the earliest streaks of the dawn appear;
And that is how men should seek their brides,—
(In the early spring) ere the ice divides.
The ferryman beckons and points to his boat:—
Let others cross over, I shall not.
The others may cross, but I say nay.
For a (true) companion here I stay."
Lament Of A Discarded Wife
When East winds blow unceasingly,
They bring out gloominess and rain.
Strive, strive to live unitedly,
And every angry thought restrain.
Some plants we gather for their leaves,
But leave the roots untouched beneath;
So, while unsullied was my name,
I should have lived with you till death.
With slow, slow step I took the road,
My inmost heart rebelling sore.
You came not far with me indeed,
You only saw me to the door.
Who calls the lettuce bitter fare?
The cress is not a whit more sweet.
Ay, feast there with your new-found bride,
Well-pleased, as when fond brothers meet.
The Wei, made turbid by the King,
Grows limpid by the iselts there.
There, feasting with your new-found bride,
For me no longer now you care.
Yet leave to me my fishing-dam;
My wicker-nets—remove them not.
My person spurned,—some vacant hour
May bring compassion for my lot.
Where ran the river full and deep,
With raft or boat I paddled o'er;
And, where it flowed in shallower stream,
I dived or swam from shore to shore.
And what we had, or what we lost,
For that I strained my every nerve;
When other folks had loss, I'd crawl
Upon my knees, if aught 'twould serve.
And you can show me no kind care,
Nay, treated like a foe am I!
My virtue stood but in your way,
Like traders' goods that none will buy.
Once it was feared we could not live;
In your reverses then I shared;
And now, when fortune smiles on you,
To very poison I'm compared.
I have laid by a goodly store,—
For winter's use it was to be;—
Feast on there with your new-found bride,—
I
was for use in poverty!
Rude fits of anger you have shown,
Now left me to be sorely tried.
Ah, you forget those days gone by,
When you came nestling to my side!
A Prince And His Officers In Trouble
Fallen so low, so low!
Wherefore not homeward go?
And we,
—how could we for our chief refuse
Exposure to the nightly dews?
Fallen so low, so low!
Wherefore not homeward go?
And did we not our chief himself require,
How lived we here in mud and mire?
Li Finds No Help In Wei
How have the creepers on the crested slope
Crept with their tendrils far and wide!
And O, ye foster-fathers of our land,
How have our days here multiplied!
Why is there never movement made?
Comes surely some expected aid.
Why is this long, protracted pause?
'Tis surely not without a cause.
With foxfurs worn and frayed, without our cars,
Came we not Eastward here to you?
O ye, the foster-fathers of our land,
Will ye have nought with us to do?
A shattered remnant, last of all our host,
But waifs and vagabonds are we!
And ye, the foster-fathers of our land,
Smile on, but deaf ye seem to be!
Buffoonery At Court
Calm and cool, see him advance!
Now for posturing and dance,
—
While the sun's in middle sky,—
There in front of platform high!
See him, corpulent and tall,
Capering in that ducal hall!
Tiger-like in strength of limb,—
Reins like ribbons were to him!
Left hand now the flute assumes,
Right hand grasps the phaesant's plumes;
Red, as though with rouge, the face.
"Give him liquor!" cries His Grace.
There are hazels on the hill,
There is fungus in the fen.
Say to whom my thoughts then flee.—
To those fine West-country men.
Those are admirable men!
The West-country men for me!
Homesick
Fain are those waters to be free,
Leaving their spring to join the K'i.
So yearns my heart for thee, dear Wei;
—
No day but there in thought I fly.
Here are my cousins, kind are they:
O, before these my plans I'll lay.
On leaving home I lodged in Tsi.
And drank the god-speed cup in Ni.
Maids, when their wedding trip they take,
Parents and brothers all forsake.
Yet let me go my aunts to greet;
Let me my elder sisters meet.
And, leaving here, I'd lodge in Kan,
Then drink the god-speed cup in Yen.
Oil me then well my axles, O!
Back in my carriage let me go.
Soon should I be in Wei—but oh!
Were I not
wrong
in acting so?
Ah!—For that land of fertile streams
Long do I sigh in waking dreams.
So when I think of Siu and Ts'o,
Full is my heart, to overflow.
Drove I but forth to wander there,
Then were unbosomed all my care.

Ah, so indeed!
Yet Heaven hath so decreed;
What therefore can I say?
On me devolves the business of the king,
On me official burdens fast encroach;
On me, at home, arriving from abroad,
My household all conspire to heap reproach
Ah, so indeed!
Yet Heaven hath so decreed;
What therefore can I say?
All urgent is the business of the king;
Official cares press on me more and more.
And when at home, arriving from abroad,
My household one and all thrust at me sore.
Ah, so indeed,
Yet Heaven hath so decreed;
What therefore can I say?
Emigrants
Cold north winds are blowing,
Heavy falls the snow.
Friend, thy hand, if thou art friendly!
Forth together let us go.
Long, too long, we loiter here:
Times are too severe.
How the north wind whistles,
Driving snow and sleet!
Friend, thy hand, if thou art friendly!
Let us, thou and I, retreat.
Long, too long, we loiter here:
Times are too severe.
Irregular Love-Making
A modest maiden, passing fair to see,
Waits at the corner of the wall for me.
I love her, yet I have no interview:
—
I scratch my head—I know not what to do.
The modest maid—how winsome was she then,
The day she gave me her vermilion pen!
Vermilion pen was never yet so bright,—
The maid's own loveliness is my delight.
Now from the pasture lands she sends a shoot
Of couchgrass fair; and rare it is, to boot.
Yet thou, my plant (when beauties I compare),
Art but the fair one's gift, and not the Fair!
The New Tower
Past the New Tower, so spick and span,
The Ho majestic rolled.
There she who sought a gallant mate
Found one deformed and old.
'Neath the New Tower's high battlements
The Ho ran smooth and still.
She sought a gallant mate, and lo!
A shapeless imbecile!
The net was ready for a fish
A goose there came instead.
And she who sought a gallant mate,
Must with this hunchback wed.
The Two Sons
Two youths there were, each took his boat,
That floated, mirrored in the stream;
—
And O the fear for those two youths,
And O the anxiety extreme!
Two youths they were, each took his boat,
And floated on the stream away;—
And O the fear for those two youths;
If harmed, yet innocent were they.


18.6: Blood Typing
Learning Objectives
- Describe the two basic physiological consequences of transfusion of incompatible blood
- Compare and contrast ABO and Rh blood groups
- Identify which blood groups may be safely transfused into patients with different ABO types
- Discuss the pathophysiology of hemolytic disease of the newborn
Blood transfusions in humans were risky procedures until the discovery of the major human blood groups by Karl Landsteiner, an Austrian biologist and physician, in 1900. Until that point, physicians did not understand that death sometimes followed blood transfusions, when the type of donor blood infused into the patient was incompatible with the patient’s own blood. Blood groups are determined by the presence or absence of specific marker molecules on the plasma membranes of erythrocytes. With their discovery, it became possible for the first time to match patient-donor blood types and prevent transfusion reactions and deaths.
Antigens, Antibodies, and Transfusion Reactions
Antigens are substances that the body does not recognize as belonging to the “self” and that therefore trigger a defensive response from the leukocytes of the immune system. (Seek more content for additional information on immunity.) Here, we will focus on the role of immunity in blood transfusion reactions. With RBCs in particular, you may see the antigens referred to as isoantigens or agglutinogens (surface antigens) and the antibodies referred to as isoantibodies or agglutinins. In this chapter, we will use the more common terms antigens and antibodies.
Antigens are generally large proteins, but may include other classes of organic molecules, including carbohydrates, lipids, and nucleic acids. Following an infusion of incompatible blood, erythrocytes with foreign antigens appear in the bloodstream and trigger an immune response. Proteins called antibodies (immunoglobulins), which are produced by certain B lymphocytes called plasma cells, attach to the antigens on the plasma membranes of the infused erythrocytes and cause them to adhere to one another.
- Because the arms of the Y-shaped antibodies attach randomly to more than one nonself erythrocyte surface, they form clumps of erythrocytes. This process is called agglutination .
- The clumps of erythrocytes block small blood vessels throughout the body, depriving tissues of oxygen and nutrients.
- As the erythrocyte clumps are degraded, in a process called hemolysis , their hemoglobin is released into the bloodstream. This hemoglobin travels to the kidneys, which are responsible for filtration of the blood. However, the load of hemoglobin released can easily overwhelm the kidney’s capacity to clear it, and the patient can quickly develop kidney failure.
More than 50 antigens have been identified on erythrocyte membranes, but the most significant in terms of their potential harm to patients are classified in two groups: the ABO blood group and the Rh blood group.
The ABO Blood Group
Although the ABO blood group name consists of three letters, ABO blood typing designates the presence or absence of just two antigens, A and B. Both are glycoproteins.  People can also have both A and B antigens on their erythrocytes, in which case they are blood type AB. People with neither A nor B antigens are designated blood type O. ABO blood types are genetically determined.
Normally the body must be exposed to a foreign antigen before an antibody can be produced. This is not the case for the ABO blood group. Individuals with type A blood—without any prior exposure to incompatible blood—have preformed antibodies to the B antigen circulating in their blood plasma. These antibodies, referred to as anti-B antibodies, will cause agglutination and hemolysis if they ever encounter erythrocytes with B antigens. Similarly, an individual with type B blood has pre-formed anti-A antibodies. Individuals with type AB blood, which has both antigens, do not have preformed antibodies to either of these. People with type O blood lack antigens A and B on their erythrocytes, but both anti-A and anti-B antibodies circulate in their blood plasma.
Rh Blood Groups
The Rh blood group is classified according to the presence or absence of a second erythrocyte antigen identified as Rh. (It was first discovered in a type of primate known as a rhesus macaque, which is often used in research, because its blood is similar to that of humans.) Although dozens of Rh antigens have been identified, only one, designated D, is clinically important. Those who have the Rh D antigen present on their erythrocytes—about 85 percent of Americans—are described as Rh positive (Rh + ) and those who lack it are Rh negative (Rh − ). Note that the Rh group is distinct from the ABO group, so any individual, no matter their ABO blood type, may have or lack this Rh antigen. When identifying a patient’s blood type, the Rh group is designated by adding the word positive or negative to the ABO type. For example, A positive (A + ) means ABO group A blood with the Rh antigen present, and AB negative (AB − ) means ABO group AB blood without the Rh antigen.
Table \(\PageIndex{1}\) summarizes the distribution of the ABO and Rh blood types within the United States.
| Blood Type | African-Americans | Asian-Americans | Caucasian-Americans | Latino/Latina-Americans |
|---|---|---|---|---|
| A + | 24 | 27 | 33 | 29 |
| A − | 2 | 0.5 | 7 | 2 |
| B + | 18 | 25 | 9 | 9 |
| B − | 1 | 0.4 | 2 | 1 |
| AB + | 4 | 7 | 3 | 2 |
| AB − | 0.3 | 0.1 | 1 | 0.2 |
| O + | 47 | 39 | 37 | 53 |
| O − | 4 | 1 | 8 | 4 |
In contrast to the ABO group antibodies, which are preformed, antibodies to the Rh antigen are produced only in Rh − individuals after exposure to the antigen. This process, called sensitization, occurs following a transfusion with Rh-incompatible blood or, more commonly, with the birth of an Rh + baby to an Rh − mother. Problems are rare in a first pregnancy, since the baby’s Rh + cells rarely cross the placenta (the organ of gas and nutrient exchange between the baby and the mother). However, during or immediately after birth, the Rh − mother can be exposed to the baby’s Rh + cells (Figure \(\PageIndex{1}\)). Research has shown that this occurs in about 13−14 percent of such pregnancies. After exposure, the mother’s immune system begins to generate anti-Rh antibodies. If the mother should then conceive another Rh + baby, the Rh antibodies she has produced can cross the placenta into the fetal bloodstream and destroy the fetal RBCs. This condition, known as hemolytic disease of the newborn (HDN) or erythroblastosis fetalis, may cause anemia in mild cases, but the agglutination and hemolysis can be so severe that without treatment the fetus may die in the womb or shortly after birth.
A drug known as RhoGAM, short for Rh immune globulin, can temporarily prevent the development of Rh antibodies in the Rh − mother, thereby averting this potentially serious disease for the fetus. RhoGAM antibodies destroy any fetal Rh + erythrocytes that may cross the placental barrier. RhoGAM is normally administered to Rh − mothers during weeks 26−28 of pregnancy and within 72 hours following birth. It has proven remarkably effective in decreasing the incidence of HDN. Earlier we noted that the incidence of HDN in an Rh + subsequent pregnancy to an Rh − mother is about 13–14 percent without preventive treatment. Since the introduction of RhoGAM in 1968, the incidence has dropped to about 0.1 percent in the United States.
Determining ABO Blood Types
Clinicians are able to determine a patient’s blood type quickly and easily using commercially prepared antibodies. An unknown blood sample is allocated into separate wells. Into one well a small amount of anti-A antibody is added, and to another a small amount of anti-B antibody. If the antigen is present, the antibodies will cause visible agglutination of the cells (Figure \(\PageIndex{2}\)). The blood should also be tested for Rh antibodies.
ABO Transfusion Protocols
To avoid transfusion reactions, it is best to transfuse only matching blood types; that is, a type B + recipient should ideally receive blood only from a type B + donor and so on. That said, in emergency situations, when acute hemorrhage threatens the patient’s life, there may not be time for cross matching to identify blood type. In these cases, blood from a universal donor —an individual with type O − blood—may be transfused. Recall that type O erythrocytes do not display A or B antigens. Thus, anti-A or anti-B antibodies that might be circulating in the patient’s blood plasma will not encounter any erythrocyte surface antigens on the donated blood and therefore will not be provoked into a response. One problem with this designation of universal donor is if the O − individual had prior exposure to Rh antigen, Rh antibodies may be present in the donated blood. Also, introducing type O blood into an individual with type A, B, or AB blood will nevertheless introduce antibodies against both A and B antigens, as these are always circulating in the type O blood plasma. This may cause problems for the recipient, but because the volume of blood transfused is much lower than the volume of the patient’s own blood, the adverse effects of the relatively few infused plasma antibodies are typically limited. Rh factor also plays a role. If Rh − individuals receiving blood have had prior exposure to Rh antigen, antibodies for this antigen may be present in the blood and trigger agglutination to some degree. Although it is always preferable to cross match a patient’s blood before transfusing, in a true life-threatening emergency situation, this is not always possible, and these procedures may be implemented.
A patient with blood type AB + is known as the universal recipient . This patient can theoretically receive any type of blood, because the patient’s own blood—having both A and B antigens on the erythrocyte surface—does not produce anti-A or anti-B antibodies. In addition, an Rh + patient can receive both Rh + and Rh − blood. However, keep in mind that the donor’s blood will contain circulating antibodies, again with possible negative implications. Figure \(\PageIndex{3}\) summarizes the blood types and compatibilities.
At the scene of multiple-vehicle accidents, military engagements, and natural or human-caused disasters, many victims may suffer simultaneously from acute hemorrhage, yet type O blood may not be immediately available. In these circumstances, medics may at least try to replace some of the volume of blood that has been lost. This is done by intravenous administration of a saline solution that provides fluids and electrolytes in proportions equivalent to those of normal blood plasma. Research is ongoing to develop a safe and effective artificial blood that would carry out the oxygen-carrying function of blood without the RBCs, enabling transfusions in the field without concern for incompatibility. These blood substitutes normally contain hemoglobin- as well as perfluorocarbon-based oxygen carriers.
Chapter Review
Antigens are nonself molecules, usually large proteins, which provoke an immune response. In transfusion reactions, antibodies attach to antigens on the surfaces of erythrocytes and cause agglutination and hemolysis. ABO blood group antigens are designated A and B. People with type A blood have A antigens on their erythrocytes, whereas those with type B blood have B antigens. Those with AB blood have both A and B antigens, and those with type O blood have neither A nor B antigens. The blood plasma contains preformed antibodies against the antigens not present on a person’s erythrocytes.
A second group of blood antigens is the Rh group, the most important of which is Rh D. People with Rh − blood do not have this antigen on their erythrocytes, whereas those who are Rh + do. About 85 percent of Americans are Rh + . When a woman who is Rh − becomes pregnant with an Rh + fetus, her body may begin to produce anti-Rh antibodies. If she subsequently becomes pregnant with a second Rh + fetus and is not treated preventively with RhoGAM, the fetus will be at risk for an antigen-antibody reaction, including agglutination and hemolysis. This is known as hemolytic disease of the newborn.
Cross matching to determine blood type is necessary before transfusing blood, unless the patient is experiencing hemorrhage that is an immediate threat to life, in which case type O − blood may be transfused.
Review Questions
Q. The process in which antibodies attach to antigens, causing the formation of masses of linked cells, is called ________.
A. sensitization
B. coagulation
C. agglutination
D. hemolysis
Answer: C
Q. People with ABO blood type O ________.
A. have both antigens A and B on their erythrocytes
B. lack both antigens A and B on their erythrocytes
C. have neither anti-A nor anti-B antibodies circulating in their blood plasma
D. are considered universal recipients
Answer: B
Q. Hemolytic disease of the newborn is a risk during a subsequent pregnancy in which ________.
 Following a motor vehicle accident, a patient is rushed to the emergency department with multiple traumatic injuries, causing severe bleeding. The patient’s condition is critical, and there is no time for determining his blood type. What type of blood is transfused, and why?
A. In emergency situations, blood type O − will be infused until cross matching can be done. Blood type O − is called the universal donor blood because the erythrocytes have neither A nor B antigens on their surface, and the Rh factor is negative.
Q. In preparation for a scheduled surgery, a patient visits the hospital lab for a blood draw. The technician collects a blood sample and performs a test to determine its type. She places a sample of the patient’s blood in two wells. To the first well she adds anti-A antibody. To the second she adds anti-B antibody. Both samples visibly agglutinate. Has the technician made an error, or is this a normal response? If normal, what blood type does this indicate?
A. The lab technician has not made an error. Blood type AB has both A and B surface antigens, and neither anti-A nor anti-B antibodies circulating in the plasma. When anti-A antibodies (added to the first well) contact A antigens on AB erythrocytes, they will cause agglutination. Similarly, when anti-B antibodies contact B antigens on AB erythrocytes, they will cause agglutination.
References
American Red Cross (US). Blood types [Internet]. c2013 [cited 2013 Apr 3]. Available from: http://www.redcrossblood.org/learn-about-blood/blood-types 2013
Glossary
- ABO blood group
- blood-type classification based on the presence or absence of A and B glycoproteins on the erythrocyte membrane surface
- agglutination
- clustering of cells into masses linked by antibodies
- cross matching
- blood test for identification of blood type using antibodies and small samples of blood
- hemolysis
- destruction (lysis) of erythrocytes and the release of their hemoglobin into circulation
- hemolytic disease of the newborn (HDN)
- (also, erythroblastosis fetalis) disorder causing agglutination and hemolysis in an Rh + fetus or newborn of an Rh − mother
- Rh blood group
- blood-type classification based on the presence or absence of the antigen Rh on the erythrocyte membrane surface
- universal donor
- individual with type O − blood
- universal recipient
- individual with type AB + blood


17: Gene Expression
Whereas each cell shares the same genome and DNA sequence, each cell does not turn on, or express, the same set of genes. Each cell type needs a different set of proteins to perform its function. Therefore, only a small subset of proteins is expressed in a cell. For the proteins to be expressed, the DNA must be transcribed into RNA and the RNA must be translated into protein. In a given cell type, not all genes encoded in the DNA are transcribed into RNA or translated into protein because specific cells in our body have specific functions. Specialized proteins that make up the eye (iris, lens, and cornea) are only expressed in the eye, whereas the specialized proteins in the heart (pacemaker cells, heart muscle, and valves) are only expressed in the heart. At any given time, only a subset of all of the genes encoded by our DNA are expressed and translated into proteins. The expression of specific genes is a highly regulated process with many levels and stages of control. This complexity ensures the proper expression in the proper cell at the proper time.
-
- 17.0: Prelude to Gene Expression
- Each somatic cell in the body generally contains the same DNA. A few exceptions include red blood cells, which contain no DNA in their mature state, and some immune system cells that rearrange their DNA while producing antibodies. In general, however, the genes that determine whether you have green eyes, brown hair, and how fast you metabolize food are the same in the cells in your eyes and your liver, even though these organs function quite differently.
-
- 17.1: Regulation of Gene Expression
- The regulation of gene expression conserves energy and space. It would require a significant amount of energy for an organism to express every gene at all times, so it is more energy efficient to turn on the genes only when they are required. In addition, only expressing a subset of genes in each cell saves space because DNA must be unwound from its tightly coiled structure to transcribe and translate the DNA.
-
- 17.2: Prokaryotic Gene Regulation
- The DNA of prokaryotes is organized into a circular chromosome supercoiled in the nucleoid region of the cell cytoplasm. Proteins that are needed for a specific function, or that are involved in the same biochemical pathway, are encoded together in blocks called operons. For example, all of the genes needed to use lactose as an energy source are coded next to each other in the lactose (or lac) operon.
-
- 17.3: Eukaryotic Epigenetic Gene Regulation
- Eukaryotic gene expression is more complex than prokaryotic gene expression because the processes of transcription and translation are physically separated. Unlike prokaryotic cells, eukaryotic cells can regulate gene expression at many different levels. Eukaryotic gene expression begins with control of access to the DNA. This form of regulation, called epigenetic regulation, occurs even before transcription is initiated.
-
- 17.4: Eukaryotic Transcription Gene Regulation
- Like prokaryotic cells, the transcription of genes in eukaryotes requires the actions of an RNA polymerase to bind to a sequence upstream of a gene to initiate transcription. However, unlike prokaryotic cells, the eukaryotic RNA polymerase requires other proteins, or transcription factors, to facilitate transcription initiation. Transcription factors are proteins that bind to the promoter sequence and other regulatory sequences to control the transcription of the target gene.
-
- 17.5: Eukaryotic Post-transcriptional Gene Regulation
- RNA is transcribed, but must be processed into a mature form before translation can begin. This processing after an RNA molecule has been transcribed, but before it is translated into a protein, is called post-transcriptional modification. As with the epigenetic and transcriptional stages of processing, this post-transcriptional step can also be regulated to control gene expression in the cell. If the RNA is not processed, shuttled, or translated, then no protein will be synthesized.
-
- 17.6: Eukaryotic Translational and Post-translational Gene Regulation
- After the RNA has been transported to the cytoplasm, it is translated into protein. Control of this process is largely dependent on the RNA molecule. As previously discussed, the stability of the RNA will have a large impact on its translation into a protein. As the stability changes, the amount of time that it is available for translation also changes.
-
- 17.7: Cancer and Gene Regulation
- Cancer is not a single disease but includes many different diseases. In cancer cells, mutations modify cell-cycle control and cells don’t stop growing as they normally would. Mutations can also alter the growth rate or the progression of the cell through the cell cycle. One example of a gene modification that alters the growth rate is increased phosphorylation of cyclin B, a protein that controls the progression of a cell through the cell cycle and serves as a cell-cycle checkpoint protein.
Thumbnail: Nucleosomes spaced far apart so that the DNA is exposed. Transcription factors can bind, allowing gene expression to occur. (CC BY 4.0 / modified from original; OpenStax ).


9.8: Completing In-Class Peer Evaluations
At a minimum, write five comments : three positive comments and two areas for improvement. Address only one criterion per comment.
- Use a “+” or “–” sign in front of each comment to help identify them easily. Address one criterion per statement.
- Start with a positive comment. Always begin by commenting on a strength.
-
Use “you,” not “he” or “she.”
- What is good? Describe using specific examples.
- Why is the behavior positive? Explain.
-
After stressing good aspects of a speech to ensure the person will continue to do what works well, point out two weaknesses/areas of improvement so the person can improve. While pointing out areas of weakness of a speech can help the speaker improve in the future, accompany each comment with a constructive alternative. Be sure to word each comment demonstrating interpersonal skills.
- What was not so good? Describe the behavior using specific examples.
- Why was the behavior considered an area of needed improvement?
- How can the speaker improve that behavior? Give a helpful coaching suggestion.
- Be specific. Study the differences between the two samples provided at the end of this chapter when it comes to specificity. What critique provides more valuable insight? What makes a comment effective or not effective?


9.13: Comet Characteristics
Comets are composed of Carbon dioxide (CO2), water ices, silicates, and organic material. The materials at the surface of the comet are of a talc-like fineness, as seen up close on Comet Tempel-1. Comets are the sources for the majority of our meteor shower “material;” the fine dust comets leave behind like bread crumbs as they orbit the sun.
The comet’s nucleus is the solid, core structure of a comet. The coma or head is the fuzzy haze that surrounds the comet’s nucleus. The tail may be made of gas, dust, or both. The coma and tail are what we see from Earth. The sizes of comet nucleus have been observed up to around 30 kilometers or 20 miles in diameter. When a comet gets close to the sun, they begin to heat up and outgas, making for the coma and sometimes a tail.
The behavior of comets is often unpredictable, due to their interactions with the sun, and other solar system dynamics. Comets, which have made numerous passages around the sun, appear to produce less dust and gas, thus less-impressive tails. Often first-time inner solar system comets can break up when passing near the sun, which was the unfortunate fate of Comet ISON in 2013.
The true nucleus of a comet has been seen six times: Halley (1986), Borrelly (2001), Wild-2 (2004), Tempel-1 (2004 and 2005), Hartley-2 (2010), and Churyumov-Gerasimenko (2014). If all goes according to plan, the European Space Agency’s Rosetta spacecraft will release a lander, called Philae, in November 2014. Philae will land on Comet Churyumov-Gerasimenko, providing us with a wealth of data.


21.14: Checklist for Straight Catheterization – Female/Male
Please follow the checklist below to review the steps for completion of “Straight Catheterization for Female/Male.”
Steps
Disclaimer: Always review and follow agency policy regarding this specific skill.
- Gather supplies: peri-care supplies, nonsterile gloves, straight catheter kit, extra pair of sterile gloves, and preprinted patient label.
-
Perform safety steps:
- Perform hand hygiene.
- Check the room for transmission-based precautions.
- Introduce yourself, your role, the purpose of your visit, and an estimate of the time it will take.
- Confirm patient ID using two patient identifiers (e.g., name and date of birth).
- Explain the process to the patient.
- Be organized and systematic.
- Use appropriate listening and questioning skills.
- Listen and attend to patient cues.
- Ensure the patient’s privacy and dignity.
- Assess ABCs.
-
Assess for latex/iodine allergies, joint limitations for positioning, and history of previous difficulties with catheterization:
- Female: Ask about previous gynecological surgeries.
- Male: Ask about previous diagnosis of enlarged prostate.
- Place the hand sanitizer and other supplies for use during/after procedure off the table near the bed.
- Place the catheter kit and peri-care supplies on the over-the-bed table.
- Secure the wastebasket and linen cart/bag near the bed for disposal.
- Ensure adequate lighting. Enlist assistance for positioning if needed.
- Raise the opposite side rail. Set the bed to a comfortable height.
- Position the patient supine and uncover the patient, exposing the patient’s groin, legs, and feet for positioning and sterile field (male = supine, legs extended; female = dorsal recumbent; may need assistance to position patient and help support legs).
- Wash your hands, apply clean gloves, and clean the perineal area.
- Remove your gloves and perform hand hygiene.
- Open the package. Take out the sterile package and place it on the table. Place the plastic package wrapping at end of the bed or on the side of the bed near you.
- Open the kit extending the outer wrapping to create a sterile field; position the sterile field on the table to create space for opening gloves at the end of the table.
- Place the sterile pad/sheet under the patient without contaminating the center of the drape by only holding onto the edges of the drape.
- Perform hand hygiene and apply sterile gloves.
- Place the fenestrated drape over the patient’s perineal area, keeping your gloves sterile by folding the corners of the sterile drape over the sterile gloves before approaching the patient.
- Remove the sterile specimen container and remove the lid, if attached. Set the container on the sterile drape and invert the lid to maintain sterility. Position the container on the sterile drape to be within reach during the procedure.
- Place the plastic tray with cotton balls and forceps on the sterile drape. Simulate opening the iodine solution and simulate pouring on the cotton balls; set the iodine package on the drape. Iodine cannot be used on mannequins.
- Locate the catheter in the bottom of the tray; leave it in the tray. Open the water-soluble sterile lubricant and empty it into the bottom of the tray.
- Put the plastic tray with saturated cotton balls horizontally on top of the tray to fit above the catheter and lubricant, which are located in the bottom of the tray.
- Make sure that the sterile specimen container is within reach of your dominant hand. Then carefully move the tray as a unit with supplies inside to the sterile drape between patient’s legs.
-
Tell the patient that you are now going to start the cleaning process and that there will be a cold sensation:
- Once the nondominant/nonsterile hand touches the patient, the position is held throughout the procedure until the catheter is inserted.
-
Inspect for the urinary meatus:
- Female: Gently spread the labia minora with your thumb and index finger of your nondominant hand and visualize the urinary meatus.

-
Cleanse the urinary meatus:
- Female: Holding the labia apart with your nondominant/nonsterile hand, use your dominant/sterile hand to hold the forceps and pick up a cotton ball soaked in antimicrobial solution and cleanse the urethra with one downward stroke each time, once on each side and then once down the center. Discard each cotton ball after use without crossing the sterile field. With the dominant sterile gloved hand, pick up the lubricated catheter about 4 inches from the end for stability. Hold the catheter loosely in your hand. Place the distal end in the receptacle.
- Male: With your sterile dominant hand, use the forceps to pick up a cotton ball. Cleanse the glans penis with the antimicrobial cleanser using a circular motion from the center of the meatus outward to the base of the glans. Discard each cotton ball after use without crossing the sterile field.  With the dominant sterile gloved hand, pick up the lubricated catheter about 4 inches from the end for stability.
- Steadily insert the catheter, maintaining sterility into the meatus until a return of urine occurs.
- Continue inserting another 1-2 inches and hold the catheter in place.
- When urine begins to drain out of the catheter, pinch the catheter with your thumb and index finger of your nondominant/nonsterile hand while continuing to hold the labia apart or penis perpendicular to the body.
- With your dominant/sterile hand, obtain the sterile specimen container from the table and put it under the catheter.
- Release clamping/pinching of the catheter, allowing urine to drain into the sterile specimen container.
- When the container is almost full, use your dominant hand to remove the container from under the stream of urine and set it on the table, maintaining sterility.
- Allow urine to continue to flow into the receptacle provided until the flow of urine stops.
- Tell the patient that the catheter will be removed. Instruct the patient to take a deep breath and exhale, and then remove the catheter and place it on the sterile drape on the bed.
- Carefully remove the urine container full of urine from the bed and place it on the kit wrapper on the table. Do not put the urine container directly on the table.
- Put the cap on the sterile specimen container, maintaining sterility.
- Remove the catheter and other supplies from the patient’s bed; provide peri-care. For males, replace foreskin if it was retracted for the procedure.
- Remove your gloves; wash hands and apply new gloves.
- Assist the patient to a comfortable position.
- Write the date, time collected, and your initials on the two preprinted patient labels.
- With an antibacterial wipe, clean the outer surface of the specimen container.
- Apply one patient label to the specimen container and one patient label to the outside of the clear biohazard bag for transport to the lab.
- Place the specimen container in the biohazard bag.
- Measure and dispose of the urine in the bathroom.
- Remove your gloves and perform hand hygiene.
- Assist the patient to a comfortable position, ask if they have any questions, and thank them for their time.
-
Ensure safety measures when leaving the room:
- CALL LIGHT: Within reach
- BED: Low and locked (in lowest position and brakes on)
- SIDE RAILS: Secured
- TABLE: Within reach
- ROOM: Risk-free for falls (scan room and clear any obstacles)
- Send the specimen to the lab for processing.
- Document the procedure and related assessment findings. Report any concerns according to agency policy.


4.2: Prokaryotic Cells
Skills to Develop
- Name examples of prokaryotic and eukaryotic organisms
- Compare and contrast prokaryotic cells and eukaryotic cells
- Describe the relative sizes of different kinds of cells
- Explain why cells must be small
Cells fall into one of two broad categories: prokaryotic and eukaryotic. Only the predominantly single-celled organisms of the domains Bacteria and Archaea are classified as prokaryotes (pro- = “before”; -kary- = “nucleus”). Cells of animals, plants, fungi, and protists are all eukaryotes (eu- = “true”) and are made up of eukaryotic cells.
Components of Prokaryotic Cells
All cells share four common components: 1) a plasma membrane, an outer covering that separates the cell’s interior from its surrounding environment; 2) cytoplasm, consisting of a jelly-like cytosol within the cell in which other cellular components are found; 3) DNA, the genetic material of the cell; and 4) ribosomes, which synthesize proteins. However, prokaryotes differ from eukaryotic cells in several ways.
A prokaryote is a simple, mostly single-celled (unicellular) organism that lacks a nucleus, or any other membrane-bound organelle. We will shortly come to see that this is significantly different in eukaryotes. Prokaryotic DNA is found in a central part of the cell: the nucleoid (Figure \(\PageIndex{1}\)).
Most prokaryotes have a peptidoglycan cell wall and many have a polysaccharide capsule (Figure \(\PageIndex{1}\)). The cell wall acts as an extra layer of protection, helps the cell maintain its shape, and prevents dehydration. The capsule enables the cell to attach to surfaces in its environment. Some prokaryotes have flagella, pili, or fimbriae. Flagella are used for locomotion. Pili are used to exchange genetic material during a type of reproduction called conjugation. Fimbriae are used by bacteria to attach to a host cell.
Career Connection: Microbiologist
The most effective action anyone can take to prevent the spread of contagious illnesses is to wash his or her hands. Why? Because microbes (organisms so tiny that they can only be seen with microscopes) are ubiquitous. They live on doorknobs, money, your hands, and many other surfaces.
However, not all microbes (also called microorganisms) cause disease; most are actually beneficial. You have microbes in your gut that make vitamin K. Other microorganisms are used to ferment beer and wine.
Microbiologists are scientists who study microbes. Microbiologists can pursue a number of careers. Not only do they work in the food industry, they are also employed in the veterinary and medical fields. They can work in the pharmaceutical sector, serving key roles in research and development by identifying new sources of antibiotics that could be used to treat bacterial infections.
Environmental microbiologists may look for new ways to use specially selected or genetically engineered microbes for the removal of pollutants from soil or groundwater, as well as hazardous elements from contaminated sites. These uses of microbes are called bioremediation technologies. Microbiologists can also work in the field of bioinformatics, providing specialized knowledge and insight for the design, development, and specificity of computer models of, for example, bacterial epidemics.
Cell Size
At 0.1 to 5.0 μm in diameter, prokaryotic cells are significantly smaller than eukaryotic cells, which have diameters ranging from 10 to 100 μm (Figure \(\PageIndex{2}\)). The small size of prokaryotes allows ions and organic molecules that enter them to quickly diffuse to other parts of the cell. Similarly, any wastes produced within a prokaryotic cell can quickly diffuse out. This is not the case in eukaryotic cells, which have developed different structural adaptations to enhance intracellular transport.
Small size, in general, is necessary for all cells, whether prokaryotic or eukaryotic. Let’s examine why that is so. First, we’ll consider the area and volume of a typical cell. Not all cells are spherical in shape, but most tend to approximate a sphere. You may remember from your high school geometry course that the formula for the surface area of a sphere is \(4\pi r^2\), while the formula for its volume is \(4\pi r^2/3\). Thus, as the radius of a cell increases, its surface area increases as the square of its radius, but its volume increases as the cube of its radius (much more rapidly). Therefore, as a cell increases in size, its surface area-to-volume ratio decreases. This same principle would apply if the cell had the shape of a cube (Figure \(\PageIndex{3}\)). If the cell grows too large, the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume. In other words, as a cell grows, it becomes less efficient. One way to become more efficient is to divide; another way is to develop organelles that perform specific tasks. These adaptations lead to the development of more sophisticated cells called eukaryotic cells.
Art Connection
Prokaryotic cells are much smaller than eukaryotic cells. What advantages might small cell size confer on a cell? What advantages might large cell size have?
Summary
Prokaryotes are predominantly single-celled organisms of the domains Bacteria and Archaea. All prokaryotes have plasma membranes, cytoplasm, ribosomes, and DNA that is not membrane-bound. Most have peptidoglycan cell walls and many have polysaccharide capsules. Prokaryotic cells range in diameter from 0.1 to 5.0 μm.
As a cell increases in size, its surface area-to-volume ratio decreases. If the cell grows too large, the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume.
Art Connections
Figure \(\PageIndex{3}\): Prokaryotic cells are much smaller than eukaryotic cells. What advantages might small cell size confer on a cell? What advantages might large cell size have?
- Answer
-
Substances can diffuse more quickly through small cells. Small cells have no need for organelles and therefore do not need to expend energy getting substances across organelle membranes. Large cells have organelles that can separate cellular processes, enabling them to build molecules that are more complex.
Glossary
- nucleoid
- central part of a prokaryotic cell in which the chromosome is found
- prokaryote
- unicellular organism that lacks a nucleus or any other membrane-bound organelle


19.1: Population Evolution
Skills to Develop
- Define population genetics and describe how population genetics is used in the study of the evolution of populations
- Define the Hardy-Weinberg principle and discuss its importance
The mechanisms of inheritance, or genetics, were not understood at the time Charles Darwin and Alfred Russel Wallace were developing their idea of natural selection. This lack of understanding was a stumbling block to understanding many aspects of evolution. In fact, the predominant (and incorrect) genetic theory of the time, blending inheritance, made it difficult to understand how natural selection might operate. Darwin and Wallace were unaware of the genetics work by Austrian monk Gregor Mendel, which was published in 1866, not long after publication of Darwin's book, On the Origin of Species . Mendel’s work was rediscovered in the early twentieth century at which time geneticists were rapidly coming to an understanding of the basics of inheritance. Initially, the newly discovered particulate nature of genes made it difficult for biologists to understand how gradual evolution could occur. But over the next few decades genetics and evolution were integrated in what became known as the modern synthesis —the coherent understanding of the relationship between natural selection and genetics that took shape by the 1940s and is generally accepted today. In sum, the modern synthesis describes how evolutionary processes, such as natural selection, can affect a population’s genetic makeup, and, in turn, how this can result in the gradual evolution of populations and species. The theory also connects this change of a population over time, called microevolution , with the processes that gave rise to new species and higher taxonomic groups with widely divergent characters, called macroevolution .
Everyday Connection: Evolution and Flu Vaccines
Every fall, the media starts reporting on flu vaccinations and potential outbreaks. Scientists, health experts, and institutions determine recommendations for different parts of the population, predict optimal production and inoculation schedules, create vaccines, and set up clinics to provide inoculations. You may think of the annual flu shot as a lot of media hype, an important health protection, or just a briefly uncomfortable prick in your arm. But do you think of it in terms of evolution?
The media hype of annual flu shots is scientifically grounded in our understanding of evolution. Each year, scientists across the globe strive to predict the flu strains that they anticipate being most widespread and harmful in the coming year. This knowledge is based in how flu strains have evolved over time and over the past few flu seasons. Scientists then work to create the most effective vaccine to combat those selected strains. Hundreds of millions of doses are produced in a short period in order to provide vaccinations to key populations at the optimal time.
Because viruses, like the flu, evolve very quickly (especially in evolutionary time), this poses quite a challenge. Viruses mutate and replicate at a fast rate, so the vaccine developed to protect against last year’s flu strain may not provide the protection needed against the coming year’s strain. Evolution of these viruses means continued adaptions to ensure survival, including adaptations to survive previous vaccines.
Population Genetics
Recall that a gene for a particular character may have several alleles, or variants, that code for different traits associated with that character. For example, in the ABO blood type system in humans, three alleles determine the particular blood-type protein on the surface of red blood cells. Each individual in a population of diploid organisms can only carry two alleles for a particular gene, but more than two may be present in the individuals that make up the population. Mendel followed alleles as they were inherited from parent to offspring. In the early twentieth century, biologists in a field of study known as population genetics began to study how selective forces change a population through changes in allele and genotypic frequencies.
The allele frequency (or gene frequency) is the rate at which a specific allele appears within a population. Until now we have discussed evolution as a change in the characteristics of a population of organisms, but behind that phenotypic change is genetic change. In population genetics, the term evolution is defined as a change in the frequency of an allele in a population. Using the ABO blood type system as an example, the frequency of one of the alleles, I A , is the number of copies of that allele divided by all the copies of the ABO gene in the population. For example, a study in Jordan 1 found a frequency of I A to be 26.1 percent. The I B and I 0 alleles made up 13.4 percent and 60.5 percent of the alleles respectively, and all of the frequencies added up to 100 percent. A change in this frequency over time would constitute evolution in the population.
The allele frequency within a given population can change depending on environmental factors; therefore, certain alleles become more widespread than others during the process of natural selection. Natural selection can alter the population’s genetic makeup; for example, if a given allele confers a phenotype that allows an individual to better survive or have more offspring. Because many of those offspring will also carry the beneficial allele, and often the corresponding phenotype, they will have more offspring of their own that also carry the allele, thus, perpetuating the cycle. Over time, the allele will spread throughout the population. Some alleles will quickly become fixed in this way, meaning that every individual of the population will carry the allele, while detrimental mutations may be swiftly eliminated if derived from a dominant allele from the gene pool. The gene pool is the sum of all the alleles in a population.
Sometimes, allele frequencies within a population change randomly with no advantage to the population over existing allele frequencies. This phenomenon is called genetic drift. Natural selection and genetic drift usually occur simultaneously in populations and are not isolated events. It is hard to determine which process dominates because it is often nearly impossible to determine the cause of change in allele frequencies at each occurrence. An event that initiates an allele frequency change in an isolated part of the population, which is not typical of the original population, is called the founder effect . Natural selection, random drift, and founder effects can lead to significant changes in the genome of a population.
Hardy-Weinberg Principle of Equilibrium
In the early twentieth century, English mathematician Godfrey Hardy and German physician Wilhelm Weinberg stated the principle of equilibrium to describe the genetic makeup of a population. The theory, which later became known as the Hardy-Weinberg principle of equilibrium, states that a population’s allele and genotype frequencies are inherently stable— unless some kind of evolutionary force is acting upon the population, neither the allele nor the genotypic frequencies would change. The Hardy-Weinberg principle assumes conditions with no mutations, migration, emigration, or selective pressure for or against genotype, plus an infinite population; while no population can satisfy those conditions, the principle offers a useful model against which to compare real population changes.
Working under this theory, population geneticists represent different alleles as different variables in their mathematical models. The variable p, for example, often represents the frequency of a particular allele, say Y for the trait of yellow in Mendel’s peas, while the variable q represents the frequency of y alleles that confer the color green. If these are the only two possible alleles for a given locus in the population, p + q = 1. In other words, all the p alleles and all the q alleles make up all of the alleles for that locus that are found in the population.
But what ultimately interests most biologists is not the frequencies of different alleles, but the frequencies of the resulting genotypes, known as the population’s genetic structure , from which scientists can surmise the distribution of phenotypes. If the phenotype is observed, only the genotype of the homozygous recessive alleles can be known; the calculations provide an estimate of the remaining genotypes. Since each individual carries two alleles per gene, if the allele frequencies (p and q) are known, predicting the frequencies of these genotypes is a simple mathematical calculation to determine the probability of getting these genotypes if two alleles are drawn at random from the gene pool. So in the above scenario, an individual pea plant could be pp (YY), and thus produce yellow peas; pq (Yy), also yellow; or qq (yy), and thus producing green peas (Figure \(\PageIndex{1}\)). In other words, the frequency of pp individuals is simply p 2 ; the frequency of pq individuals is 2pq; and the frequency of qq individuals is q 2 . And, again, if p and q are the only two possible alleles for a given trait in the population, these genotypes frequencies will sum to one: p 2 + 2pq + q 2 = 1.
Exercise \(\PageIndex{1}\)
In plants, violet flower color (V) is dominant over white (v). If p = 0.8 and q = 0.2 in a population of 500 plants, how many individuals would you expect to be homozygous dominant (VV), heterozygous (Vv), and homozygous recessive (vv)? How many plants would you expect to have violet flowers, and how many would have white flowers?
- Answer
-
The expected distribution is 320 VV, 160Vv, and 20 vv plants. Plants with VV or Vv genotypes would have violet flowers, and plants with the vv genotype would have white flowers, so a total of 480 plants would be expected to have violet flowers, and 20 plants would have white flowers.
In theory, if a population is at equilibrium—that is, there are no evolutionary forces acting upon it—generation after generation would have the same gene pool and genetic structure, and these equations would all hold true all of the time. Of course, even Hardy and Weinberg recognized that no natural population is immune to evolution. Populations in nature are constantly changing in genetic makeup due to drift, mutation, possibly migration, and selection. As a result, the only way to determine the exact distribution of phenotypes in a population is to go out and count them. But the Hardy-Weinberg principle gives scientists a mathematical baseline of a non-evolving population to which they can compare evolving populations and thereby infer what evolutionary forces might be at play. If the frequencies of alleles or genotypes deviate from the value expected from the Hardy-Weinberg equation, then the population is evolving.
Summary
The modern synthesis of evolutionary theory grew out of the cohesion of Darwin’s, Wallace’s, and Mendel’s thoughts on evolution and heredity, along with the more modern study of population genetics. It describes the evolution of populations and species, from small-scale changes among individuals to large-scale changes over paleontological time periods. To understand how organisms evolve, scientists can track populations’ allele frequencies over time. If they differ from generation to generation, scientists can conclude that the population is not in Hardy-Weinberg equilibrium, and is thus evolving.
Footnotes
- 1 Sahar S. Hanania, Dhia S. Hassawi, and Nidal M. Irshaid, “Allele Frequency and Molecular Genotypes of ABO Blood Group System in a Jordanian Population,” Journal of Medical Sciences 7 (2007): 51-58, doi:10.3923/jms.2007.51.58.
Glossary
- allele frequency
- (also, gene frequency) rate at which a specific allele appears within a population
- founder effect
- event that initiates an allele frequency change in part of the population, which is not typical of the original population
- gene pool
- all of the alleles carried by all of the individuals in the population
- genetic structure
- distribution of the different possible genotypes in a population
- macroevolution
- broader scale evolutionary changes seen over paleontological time
- microevolution
- changes in a population’s genetic structure
- modern synthesis
- overarching evolutionary paradigm that took shape by the 1940s and is generally accepted today
- population genetics
- study of how selective forces change the allele frequencies in a population over time


4.1: “Question-Begging” Arguments
Many common arguments about abortion are what’s called “question-begging,” which means the reason given for the conclusion assumes that conclusion. This means that you wouldn’t accept the reason as a good reason to believe the conclusion unless you already believed that conclusion. This is circular reasoning, and so arguments like this are always bad.
“Against” Abortion
Many common arguments against abortion are question begging. Here are some:
Abortion— killing fetuses to end pregnancies— is wrong because:
- abortion is murder ;
- abortion is killing babies or children ;
- adoption is a better option than abortion;
- pregnant women just must keep the pregnancy and give birth;
- abortion should not be used as ‘birth control’;
- women who have abortions are irresponsible ;
- a good person wouldn’t have an abortion;
- some women who have abortions feel guilty , and all should .
These often-heard claims all assume that abortion is wrong. To explain:
- (1) assumes that killing fetuses is wrong, since “murder” means wrongful killing;
- (2) assumes that fetuses are like babies and children and so are similarly wrong to kill;
- (3) assumes that abortion is a worse or bad option, since it assumes it is wrong;
- (4) assumes that women must not have abortions since it assumes abortions are wrong;
- (5) assumes that abortion is wrong: if abortion is not wrong , it could permissibly be used as a form of “birth control,” even if is not an ideal form of that;
- (6) assumes that women who have abortions are doing what they are not supposed to do, doing wrong, and so are “irresponsible”;
- (7) assumes that abortion is wrong and so good people, who avoid wrongdoing, wouldn’t have one;
- (8) assumes that abortion is wrong and so assumes that some women feel guilty because they have done something wrong: but since people can feel guilty even if they haven’t done anything wrong, guilty feelings aren’t perfect evidence of wrongdoing (just as not feeling guilty doesn’t mean you did something that was permissible).
People would believe these claims only if they already believed abortion is wrong, so these claims should not sway anyone who wants to think critically about the topic.
“For” Abortion
People who believe abortion should be allowed also sometimes give question-begging arguments. Here are a few:
Abortion is not wrong because:
- abortion is a personal choice ; couples should be able to make that choice;
- women have a (moral) right to have abortions;
- women have the right to do what they want with their bodies;
- well, if you don’t like abortions, then don’t have one !
- those who oppose abortions just want to control women.
These commonly-given claims likewise assume their conclusions. To explain:
- the idea of a “personal choice” seems to be a choice that’s not wrong to make: e.g., we wouldn’t call a choice to be an ax-murderer a “personal choice” because that’s wrong, whereas what color socks to wear is a “personal choice.” So claims like (1) seem to just assume that abortion is not wrong or that it should be legal;
- when people say that they have a moral right to do something, sometimes they are merely saying that it’s not wrong for them to do it . So (2) amounts to saying that abortion is not wrong because it’s not wrong, which is question-begging. (If it’s explained why women have this right, the argument might cease to be question-begging, however);
- about (3), there are limits to rights, and sometimes we don’t have the legal or moral right to do what’s wrong. If abortion were wrong, then perhaps women wouldn’t have the right to have them, and this claim just assumes abortions are not wrong;
- about (4), consider an analogous slogan, “Don’t like arson? Then don’t burn down any buildings !” This is absurd, because arson is wrong, and we don’t offer slogans like this about actions that are wrong. “Don’t like strawberries? Then don’t eat them !” makes sense since not eating strawberries is not wrong. Slogan (4) assumes that abortion is not wrong;
- about (5), since some wrongdoing should be “controlled,” those who offer (5) might merely assume that abortion is not a type of wrongdoing that should be illegal. They are also focusing on other people’s motives, which is often unwise: people who allegedly wish to “control” women might respond or suspect that abortion advocates are often motivated by a desire to “engage in immorality without consequences!” ( Is that true? No, pro-choice advocates argue.) Accusations about motives are fruitless: it’s better to engage the basic questions of whether abortion is wrong or not and why , like we are doing here, instead of speculating about motives.
Question-begging arguments are common, on many issues, not just abortion, and they should be rejected, by everyone, always.


Bound morphemes can do one of two different jobs. Inflectional morphology conveys grammatical information, such as number, tense, agreement or case. English has relatively few inflectional morphemes, but many other languages have much richer systems of inflectional morphology.
A YouTube element has been excluded from this version of the text. You can view it online here:
https://ecampusontario.pressbooks.pub/essentialsoflinguistics/?p=117
Check Yourself
1. What type of grammatical information does the inflectional affix in the word
speeches
communicate?
-
Number.
-
Tense.
-
Subject agreement.
-
Case.
2. What type of grammatical information does the inflectional affix in the word
climbed
communicate?
-
Number.
-
Tense.
-
Subject agreement.
-
Case.
3. What type of grammatical information does the inflectional difference between
he
and
him
indicate?
-
Number.
-
Tense.
-
Subject agreement.
-
Case.
Answers
Video Script
We saw in our last units that words can be made up of morphemes, which are the smallest linguistic unit that links form with meaning. Morphemes can do a couple of quite different jobs in a word.
Inflectional
morphemes are morphemes that add grammatical information to a word. When a word is inflected, it still retains its core meaning, and its category stays the same. We’ve actually already talked about several different inflectional morphemes:
The
number
on a noun is inflectional morphology. For most English nouns the inflectional morpheme for the
plural
is an
–s
or
–es
(e.g.,
books, cars, dishes
) that gets added to the singular form of the noun, but there are also a few words with irregular plural morphemes. Some languages also have a special morpheme for the
dual
number, to indicate exactly two of something. Here’s an example from Manam, one of the many languages spoken in Papua New Guinea. You can see that there’s a morpheme on the noun woman that indicates dual, for exactly two women, and a different morpheme for plural, that is, more than two women.
|
Manam (Papua New Guinea)
|
|
|
|
/áine ŋara/
|
that woman
|
singular
|
|
/áine ŋara
diaru
/
|
those two women
|
dual
|
|
/áine ŋara
di
/
|
those women
|
plural
|
The
tense
on a verb is also inflectional morphology. For many English verbs, the past tense is spelled with an
–ed
, (
walked, cooked, climbed
) but there are also many English verbs where the tense inflection is indicated with a change in the vowel of the verb (
sang, wrote, ate
). English does not have a bound morpheme that indicates future tense, but many languages do.
Another kind of inflectional morphology is
agreement
on verbs. If you’ve learned French or Spanish or Italian, you know that the suffix at the end of a verb changes depending on who the subject of the verb is. That’s agreement inflection. Here are some examples from French. You can see that there’s a different morpheme on the end of each verb depending on who’s doing the singing.
|
French
|
|
1st
|
je chante
|
I sing
|
|
2d
|
tu chantes
|
you sing
|
|
3d
|
elle chante
|
she sings
|
|
1st
|
nous chantons
|
we sing
|
|
2d
|
vous chantez
|
you (pl.) sing
|
|
3d
|
elles chantent
|
they sing
|
And in some languages, the morphology on a noun changes depending on the noun’s role in a sentence; this is called
case
inflection. Take a look at these two sentences in German: The first one,
Der Junge sieht Sofia
, means that, “The boy sees Sofia”. Look at the form of the phrase,
the boy, “der Junge”
. Now, look at this other sentence,
Sofia sieht den Jungen
, which means that “Sofia sees the boy”. In the first sentence, the boy is doing the seeing, but in the second, the boy is getting seen, and the word for boy,
Junge
has a different morpheme on it to indicate its different role in the sentence. That’s an example of
case
morphology, which is another kind of inflection.
|
German
|
|
Der Junge sieht Sofia.
|
The boy sees Sofia.
|
|
Sofia sieht den Jungen
|
Sofia sees the boy.
|