9.3: Faraday’s Law
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Learning Objectives
By the end of this section, you will be able to:
- Determine the magnetic flux through a surface, knowing the strength of the magnetic field, the surface area, and the angle between the normal to the surface and the magnetic field
- Use Faraday’s law to determine the magnitude of induced emf in a closed loop due to changing magnetic flux through the loop
The first productive experiments concerning the effects of time-varying magnetic fields were performed by Michael Faraday in 1831. One of his early experiments is represented in Figure \(\PageIndex{1}\). An emf is induced when the magnetic field in the coil is changed by pushing a bar magnet into or out of the coil. Emfs of opposite signs are produced by motion in opposite directions, and the directions of emfs are also reversed by reversing poles. The same results are produced if the coil is moved rather than the magnet—it is the relative motion that is important. The faster the motion, the greater the emf, and there is no emf when the magnet is stationary relative to the coil.
Faraday also discovered that a similar effect can be produced using two circuits—a changing current in one circuit induces a current in a second, nearby circuit. For example, when the switch is closed in circuit 1 of Figure \(\PageIndex{1a}\), the ammeter needle of circuit 2 momentarily deflects, indicating that a short-lived current surge has been induced in that circuit. The ammeter needle quickly returns to its original position, where it remains. However, if the switch of circuit 1 is now suddenly opened, another short-lived current surge in the direction opposite from before is observed in circuit 2.
Faraday realized that in both experiments, a current flowed in the circuit containing the ammeter only when the magnetic field in the region occupied by that circuit was changing . As the magnet of the figure was moved, the strength of its magnetic field at the loop changed; and when the current in circuit 1 was turned on or off, the strength of its magnetic field at circuit 2 changed. Faraday was eventually able to interpret these and all other experiments involving magnetic fields that vary with time in terms of the following law.
Faraday's Law
The emf \(\epsilon\) induced is the negative change in the magnetic flux \(\Phi_m\) per unit time. Any change in the magnetic field or change in orientation of the area of the coil with respect to the magnetic field induces a voltage (emf).
The magnetic flux is a measurement of the amount of magnetic field lines through a given surface area, as seen in Figure \(\PageIndex{3}\). This definition is similar to the electric flux studied earlier. This means that if we have
\[\Phi_m = \int_S \vec{B} \cdot \hat{n}dA, \nonumber \]
then the induced emf or the voltage generated by a conductor or coil moving in a magnetic field is
\[\epsilon = - \dfrac{d}{dt} \int_S \vec{B} \cdot \hat{n} dA = - \dfrac{d\Phi_m}{dt}. \nonumber \]
The negative sign describes the direction in which the induced emf drives current around a circuit. However, that direction is most easily determined with a rule known as Lenz’s law, which we will discuss shortly.
 Notice that S is an open surface . It can be shown that any open surface bounded by the circuit in question can be used to evaluate \(\Phi_m\). For example, \(\Phi_m\) is the same for the various surfaces \(S_1, \, S_2, . . .\) of part (b) of the figure.
The SI unit for magnetic flux is the weber (Wb),
\[1 \, Wb = 1 \, T \cdot m^2. \nonumber \]
Occasionally, the magnetic field unit is expressed as webers per square meter ( \(Wb /m^2\)) instead of teslas, based on this definition. In many practical applications, the circuit of interest consists of a number N of tightly wound turns (Figure \(\PageIndex{5}\)). Each turn experiences the same magnetic flux. Therefore, the net magnetic flux through the circuits is N times the flux through one turn, and Faraday’s law is written as
\[\epsilon = - \dfrac{d}{dt}(N\Phi_m) = - N \dfrac{d\Phi_m}{dt}. \nonumber \]
A Square Coil in a Changing Magnetic Field
The square coil of Figure \(\PageIndex{1}\) has sides \(l = 0.25 \, m\) long and is tightly wound with \(N = 200\) turns of wire. The resistance of the coil is \(R = 5.0 \, \Omega\) The coil is placed in a spatially uniform magnetic field that is directed perpendicular to the face of the coil and whose magnitude is decreasing at a rate \(dB/dt = -0.040 \, T/s\). (a) What is the magnitude of the emf induced in the coil? (b) What is the magnitude of the current circulating through the coil?
Strategy
The area vector, or \(\hat{n}\) direction, is perpendicular to area covering the loop. We will choose this to be pointing downward so that \(\vec{B}\) is parallel to \(\hat{n}\) and that the flux turns into multiplication of magnetic field times area. The area of the loop is not changing in time, so it can be factored out of the time derivative, leaving the magnetic field as the only quantity varying in time. Lastly, we can apply Ohm’s law once we know the induced emf to find the current in the loop.
Solution
- The flux through one turn is \[\Phi_m = BA = Bt^2, \nonumber \]
so we can calculate the magnitude of the emf from Faraday’s law. The sign of the emf will be discussed in the next section, on Lenz’s law: \[|\epsilon| = \left|-N\dfrac{d\Phi_m}{dt}\right| = Nl^2 \dfrac{dB}{dt} \nonumber \]\[= (200)(0.25 \, m)^2 (0.040 \, T/s) = 0.50 \, V. \nonumber \]
- The magnitude of the current induced in the coil is \[I = \dfrac{\epsilon}{R} = \dfrac{0.50 \, V}{5.0 \, \Omega} = 0.10 \, A. \nonumber \]
Significance
If the area of the loop were changing in time, we would not be able to pull it out of the time derivative. Since the loop is a closed path, the result of this current would be a small amount of heating of the wires until the magnetic field stops changing. This may increase the area of the loop slightly as the wires are heated.
Exercise \(\PageIndex{1}\)
A closely wound coil has a radius of 4.0 cm, 50 turns, and a total resistance of \(40 \, \Omega\). At what rate must a magnetic field perpendicular to the face of the coil change in order to produce Joule heating in the coil at a rate of 2.0 mW?
Solution
1.1 T/s


6.2: Eukaryotic Gene Regulation
Learning Objectives
- Describe the cis -acting elements that control tissue-specific transcription of eukaryotic protein encoding genes: promoters, enhancers, insulators and how trans- acting transcription factors can influence gene expression.
- Predict the effects of mutations in regulatory sequences on gene expression.
Like prokaryotes, transcriptional regulation in eukaryotes involves both cis -elements and trans -factors; however, there are more factors and they interact in more complex ways, many of which are still be elucidated.
Regulatory sequences
Proximal regulatory sequences
As in prokaryotes the RNA polymerase binds to the gene at its promoter to begin transcription. In eukaryotes, however, RNA polymerase is part of a large protein complex that includes additional proteins (transcription initiation factors) that bind to one or more specific cis -elements in the promoter region, including GC-rich boxes, CAAT boxes, and TATA boxes. High levels of transcription require both the presence of this protein complex at the promoter, as well as their interaction with other trans -factors described below. The approximate position of these elements is described relative to the transcription start site (+1), but the distance between any of these elements and the transcription start site can vary. These sites are typically within ~200 base pairs of the start of transcription.
Distal regulatory elements
Even more variation is observed in the position and orientation of the second major type of cis -regulatory element in eukaryotes, which are DNA sequences called enhancer elements or simply enhancers. Regulatory trans -factor proteins called transcription factors bind to specific enhancer sequences, then, while still bound to DNA, these proteins interact with RNA polymerase and other proteins at the promoter to enhance the rate of transcription. There are a wide variety of different transcription factors and each recognizes a specific DNA sequence (enhancer element) to promote gene expression in the adjacent gene under specific circumstances. Enhancers can be located near (~100s of bp) or far (~10K of bp), and either upstream or downstream, from the promoter. The transcription factors and the proteins associated with transcription initiation complex will bind each other, bending the DNA in the process.
Enhancer sequence example
Some genes are transcriptionally regulated in response to hormones, such as estrogen. Estrogen receptors are proteins that bind the hormone estrogen and the the protein dimers are transported into the nucleus where they recognize sequences called estrogen response elements (EREs). The consensus ERE sequence is 5′-GGTCAnnnTGACC-3′ (where n is any base) at many locations in a genome and recruit RNA polymerase to induce the transcription of the corresponding genes. This consensus sequence was elucidated by studies of a human cell line to which a Xenopus (frog) estrogen responsive gene had been added, revealing that the roles of estrogen receptors in binding EREs and activating transcription of target genes is conserved across species.
Klein-Hitpass L, Schorpp M, Wagner U, Ryffel GU. An estrogen-responsive element derived from the 5' flanking region of the Xenopus vitellogenin A2 gene functions in transfected human cells. Cell. 1986 Sep 26;46(7):1053-61. doi: 10.1016/0092-8674(86)90705-1. PMID: 3463433.
Reviewed by Klinge C. Nucleic Acids Res. 2001 Jul 15; 29(14): 2905–2919.
Enhancers regulate the Drosophila yellow gene
The yellow gene of Drosophila provides an example of the modular nature of enhancers. This gene encodes an enzyme in the pathway that produces a dark pigment in the insect exoskeleton. Mutants have a yellow cuticle rather than the wild type darker pigmented cuticle. (Why call the gene “yellow”? Recall that genes are often named after their mutant phenotype.) Three enhancer elements each bind a different tissue-specific transcription factor in the wing, body, or mouth to enhance transcription of yellow in that tissue and make the dark pigment. So, the wing cells will have a transcription factor that binds to the wing enhancer to drive expression; likewise in the body and mouth cells. Thus, specific combinations of cis -elements and trans -factors control the differential, tissue-specific expression of genes. This type of combinatorial action of enhancers is typical of the transcriptional activation of most eukaryotic genes: specific transcription factors activate the transcription of target genes under specific conditions.
While enhancer sequences promote expression, there is an oppositely acting type of element, called silencers. These elements function in much the same manner, with transcription factors that bind to DNA sequences, but they act to repress or reduce transcription from the adjacent gene. A gene’s complete expression profile (transcription level, tissue specific, temporal specific) is a combination of various enhancer and silencer elements
Thinking about regulation of transcription factors
Understanding the transcription factors that regulate the expression of the yellow gene can prompt us to consider: why are those transcription factors present in different tissues? These transcription factors themselves are regulated by their own sets of transcription factors and so on and so on. Where does it begin? For Drosophila, the answer is in the egg! Specific proteins and mRNAs in the egg define the regions of the future embryo and a cascade of gene expression events lead to each adult cell and tissue type expressing the correct genes for their function.
Exercise \(\PageIndex{1}\)
What is the phenotype of the fruit fly when the yellow gene and enhancers are fully functional?
What would be the effect of a loss-of-function mutation in the yellow coding sequence?
What would be the effect of a mutation in the wing enhancer?
What would be the effect of a mutation in the TATA box region?
- Answer
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The wild-type fruit fly has a dark black/brown cuticle.
A loss-of-function mutation in the yellow gene would lead to flies with yellow appearance, instead of brown/black.
A mutation in the wing enhancer would result in yellow wings, but other parts of cuticle should be unaffected.
A mutation in the TATA box should result in a phenotype similar to loss-of-function in the yellow gene.
Contributors and Attributions
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Dr. Todd Nickle and Isabelle Barrette-Ng (Mount Royal University) The content on this page is licensed under CC SA 3.0 licensing guidelines.
Using reporter genes to study transcription


11.1.1A: Race
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Learning Objectives
- Interpret ”the ideology of race” based on examples from the text
While many people conflate the terms “race” and ” ethnicity,” these terms have distinct meanings for sociologists. The idea of race refers to superficial physical differences that a particular society considers significant, while ethnicity is a term that describes shared culture.
Social and Scientific Conceptions of Race
Historically, the concept of race has changed across cultures and eras. Race has been used as a classification system to categorize humans in a variety of ways: as large and distinct populations, as groups distinguished by phenotype (observable traits and behaviors), and as groups of differing geographic ancestry and ethnicity. In the past, theorists have posited categories of race based on various geographic regions, ethnicities, skin colors, and more. Their labels for racial groups have connoted regions (Mongolia and the Caucus Mountains, for instance) or denoted skin tones (black, white, yellow, and red, for example). It was assumed for centuries that race was based in biology and genetically distinguishable among different subgroups (e.g., African Americans, Caucasians, American Indians, etc.).
However, this typology of race developed during early racial science has fallen into disuse; over time the concept has become less connected with ancestral and family ties and more concerned with superficial physical characteristics. While biologists sometimes use the concept of race to make distinctions among sets of traits, others in the scientific community suggest that this idea of race is often used in a naive or simplistic way.
Now, race is far more widely accepted to be a social construction and therefore not distinguishable based on biology alone. Among humans, race has no taxonomic significance — all living humans belong to the same hominid subspecies Homo sapiens sapiens . Social conceptions and groupings of races vary over time, according to different folk taxonomies that define essential types of individuals based on perceived traits. Many scientists consider this sort of biological essentialism obsolete, and generally discourage racial explanations in favor of other physical or behavioral distinctions.
Early Modern Conceptions of Race
The word “race” was originally used to refer to any nation or ethnic group. For example, the 13 th century traveler Marco Polo used the term “Persian race”, to describe people inhabiting the territory of the nation-state Iran.
However, anthropologists only trace the current concept of “race,” along with many of the ideas now associated with the term, to the 16 th and 17 th centuries and the time of the Scientific Revolution. This era was one of European imperialism and colonization, during which new – often exploitive – political relations were established between Europeans and other cultures of the world. As Europeans encountered people from different parts of the world, they speculated about the physical, social, and cultural differences among various human groups.
According to historian Milton Meltzer, the rise of the Atlantic slave trade created a further incentive to categorize human groups in order to justify the subordination of African slaves. Similarly, the tradition of hostility between the English and Irish was a powerful influence on early European thinking of the Irish as an inferior “race. ”
As Europeans began to sort themselves and others into groups based on physical appearance, they attributed to individual members of these groups certain behaviors and capacities that were supposedly deeply ingrained. These supposed physical, intellectual, behavioral, and moral differences soon became part of common folk belief.
From the 17 th through the 19 th centuries, the merging of folk beliefs about and scientific explanations of group differences produced what social anthropologist Audrey Smedley has called an “ideology of race. ” According to this ideology, races are primordial, natural, enduring and distinct. During this time, it was further argued that some groups may be the result of mixture between formerly distinct populations, but that careful study could distinguish the ancestral races that had combined.
Contemporary Uses of Racial Categories
Contemporary conceptions of race illuminate how far removed modern race understanding is from biological qualities. In modern society, some people who consider themselves “white” actually have more melanin (a pigment that determines skin color) in their skin than other people who identify as “black. ” In some countries, such as Brazil, class is more important than skin color in determining racial categorization. People with high levels of melanin in their skin may consider themselves “white” if they enjoy a middle-class lifestyle. On the other hand, someone with low levels of melanin in their skin might be assigned the identity of “black” if they have little education or money.
While race is largely understood to be a social construct, most scholars agree that race has real material effects in the lives of people through institutionalized practices of preference and discrimination. Socioeconomic factors, in combination with early but enduring views of race, have led to considerable suffering within disadvantaged racial groups. Racial discrimination often coincides with racist mindsets, whereby the individuals and ideologies of one group come to perceive the members of an outgroups as both racially defined and morally inferior. As a result, racial groups possessing relatively little power often find themselves excluded or oppressed. Racism today continues to contribute to the suffering of many people in the form of slavery, genocide, systemic oppression, and institutionalized discrimination.
Law enforcement officers often utilize race to profile suspects, a term commonly referred to as “racial profiling”. This use of racial categories is frequently criticized for perpetuating an outmoded understanding of human biological variation, and promoting stereotypes.
Key Points
- Phenotype refers to the composite observable traits and behaviors of an individual or group.
- Geneotype refers to a person’s genetic makeup.
- Among humans, race has no taxonomic significance — all living humans belong to the same hominid subspecies, Homo sapiens sapiens .
- An ” ideology of race,” formed through the merging of folk beliefs about group differences with scientific explanations of those differences, argued that races are primordial, natural, enduring and distinct.
Key Terms
- ideology of race : The belief that races are primordial, natural, enduring, and distinct, derived from folk beliefs and scientific explanations generated during the 17th-19th centuries.
- race : A large group of people distinguished from others on the basis of a common heritage or common physical characteristics, such as skin color and hair type.
- phenotype : Any observable characteristic of an organism, such as its morphological, developmental, biochemical or physiological properties, or its behavior.


34.16: Equality? I don’t think so.
The film The Help , directed by Tate Taylor, was released in 2011. It focuses on the civil rights movement in the early 1960s in Mississippi. The film focuses on the main character and the book she decides to write–a book which includes the points of view of African American maids who work for white families, exposing the reality of their lives, and the treatment they receive. Skeeter, the main character who is writing the book about the maids, is a white female and was raised with the Southern ideal that African Americans are less than white people and should be treated as such. Even though Skeeter does not buy into this ideal, her family and peers do, and get angry when the book is published because they don’t think that anything is wrong.  Things are just fine around here” (Taylor).
The Help adapts early American literature by giving a visual representation of the treatment that African Americans received in Southern America and white people’s resistance to giving them equality, failing to acknowledge that they are actual humans. Hilly, another character in the movie, spends most of the film working on an initiative that would require households to have a separate bathroom for the maids.  The audience frequently sees the blatant disgust on Hilly’s face when the “colored situation” as she calls it is brought up.
https://youtu.be/mu36YYhJTb8?t=87
Like many forms of early American literature, The Help focuses on the systematic discrimination and oppression against African Americans by white communities and how, throughout history, that hasn’t really changed. The movie takes place in the early 60s, long after the Civil War, and African Americans are still being denied their rights and are still being treated as subhuman. The film also touches on how unsafe it is for African Americans to mingle with white people outside of work. In one scene, Skeeter is trying to persuade Aibileen to share some of her stories for the book which makes Aibileen visibly terrified. Skeeter promises that they will be careful to which Aibeleen replies “this already ain’t careful, Ms. Skeeter”, referring to them just talking about Skeeter’s book in the open. Within the next few scenes we learn that what Skeeter wants to do is against the law and could get her and anyone helping her arrested.
The film works as early American literature in the way that it is exposing the treatment and lifestyles in the southern part of the country that might not have otherwise been shown. Americans tend to hide the ugly parts of history because it’s embarrassing; it is a stain on American history, we don’t want to think that the people of America are capable of such cruelty, and so it is ignored and buried underneath all the greatness of the country. The Help focuses on the Civil Rights movement on a more personal, individual level. We get to see inside the lives of Minnie, Aibeleen, and other maids as well as the lives of the women who employ them. Because it is a film, we get to see how each person’s life is affected, we get to see how hard the characters have to fight for the lives they have, and because it is a film , we get a more personal experience. If we were to watch the Civil Rights movement being covered by a news station, there would be no introductions, it wouldn’t be as emotional. But because we have been introduced to a small circle of people, we are able to sympathize with them and hope for their success. The theme of The Help holds true with other texts we have read in class and other films that deal with white people interacting with oppressed or enslaved African Americans. In The Heroic Slave , without the help of Listwell (a white man), Washington’s rebellion would have been unsuccessful. In a film called The Free State of Jones , a Civil War deserter named Newton Knight helped to lead a successful slave rebellion and helps a group of freed slaves get the chance to vote. In The Help , Skeeter is giving the maids a voice and a chance to be heard by writing and publishing a book filled with their stories. In all of these situations, African American people are only able to have successful uprisings and are given a widely heard voice because a white person gave it to them.
The fact that The Help is a film as well as a text is important because it broadens the audience and draws more attention to the story. In today’s world, most people prefer the TV screen to a book or newspaper because it’s easily accessible, easier to understand, and a story can be told in the fraction of the time it takes to read a novel. The box office earnings for the film adaptation totaled nearly $170,000,000 in the U.S. alone, whereas the novel only made around $850,000 in sales ( The Help ). Today, American literature is largely consumed through modes of media like a movie theater, social media and sites like YouTube. Technology has made it easier and faster to spread information and things like films, and they’re easily accessible. Netflix, Hulu, Amazon Prime, HBO and other streaming sites make the availability of electronic literature almost unlimited for a monthly charge, which is heavily influencing the types of literature being produced and consumed.
Media and digital technology is changing the study of American literature by switching focus from traditional print texts to films, commercials and TV shows (texts that we analyzed in Studies in English). Instead of close reading a print text, analyzing it and writing a paper on it, we close read the film Get Out . We also looked at commercials and parts of a TV show and discussed the messages being sent from them. We did the same thing earlier this semester when we looked at a scene from Pocahontas and examined the film’s larger implications. The gradual shift from traditional texts to digital forms of literature is changing my understanding of American literature because it’s showing that literature is not strictly in paper form. It has evolved into several different forms that are being integrated into education as well as people’s everyday lives.
Taylor, Tate, director. The Help. 10 Aug. 2011, www.imdb.com/title/tt1454029/ .
“The Help (2011) – Financial Information.” The Numbers – Where Data and Movies Meet, 10 Aug. 2011, www.the-numbers.com/movie/Help-The#tab=summary.


4.3: Websites
Alzheimer’s Association is a national non-profit with local chapters that advance research to end Alzheimer’s and Dementia while enhancing care for those living with the disease and supporting their families .
Link to articles about the disease:
Comprehensive resource for families and professionals on family caregiving. Fact sheets on many topics, information about public policy, and evidence-based practices.
ADEAR -Alzheimer’s Disease Education and Referral Center – National Institutes of Health
The National Institutes of Health resource on Alzheimer’s disease. Articles and research information for families and professionals. See “Caring for a Person with Alzheimer’s Disease, Your Easy to Use Guide from the National Institute on Aging.”
The National Caregivers Library is an extensive resource of article, forms, checklists and topic-specific resources related to aging, chronic disease and caregiving. It includes comprehensive sections caregiving basics, caregiver resources and Alzheimer’s disease.
Cleveland Clinic is a non-profit academic center that integrates clinical care with research and education. Though its health education department patients, students and educators can access nearly 5,000 health articles, videos, and tools to help manage your health.
Powerful Tools for Caregivers and the Caregiver Helpbook
An evidence-based group education programs for family caregivers that provides tools and strategies to reduce stress, communicate more effectively with providers and family, manage difficult feelings and make touch caregiving decisions. The Caregiver Helpbook is also available for purchase on this site.


4.19: Connections between Cells and Cellular Activities - Intercellular Junctions
- Describe the purpose of intercellular junctions in the structure of cells
Intercellular Junctions
The extracellular matrix allows cellular communication within tissues through conformational changes that induce chemical signals, which ultimately transform activities within the cell. However, cells are also capable of communicating with each other via direct contact through intercellular junctions.
There are some differences in the ways that plant and animal cells communicate directly. Plasmodesmata are junctions between plant cells, whereas animal cell contacts are carried out through tight junctions, gap junctions, and desmosomes.
Junctions in Plant Cells
In general, long stretches of the plasma membranes of neighboring plant cells cannot touch one another because they are separated by the cell wall that surrounds each cell. How then can a plant transfer water and other soil nutrients from its roots, through its stems, and to its leaves? This transport primarily uses the vascular tissues (xylem and phloem); however, there are also structural modifications called plasmodesmata (singular: plasmodesma) that facilitate direct communication in plant cells. Plasmodesmata are numerous channels that pass between cell walls of adjacent plant cells and connect their cytoplasm; thereby, enabling materials to be transported from cell to cell, and thus throughout the plant.
Junctions in Animal Cells
Communication between animal cells can be carried out through three types of junctions. The first, a tight junction, is a watertight seal between two adjacent animal cells. The cells are held tightly against each other by proteins (predominantly two proteins called claudins and occludins). This tight adherence prevents materials from leaking between the cells. These junctions are typically found in epithelial tissues that line internal organs and cavities and comprise most of the skin. For example, the tight junctions of the epithelial cells lining your urinary bladder prevent urine from leaking out into the extracellular space.
Also found only in animal cells are desmosomes, the second type of intercellular junctions in these cell types. Desmosomes act like spot welds between adjacent epithelial cells, connecting them. Short proteins called cadherins in the plasma membrane connect to intermediate filaments to create desmosomes. The cadherins join two adjacent cells together and maintain the cells in a sheet-like formation in organs and tissues that stretch, such as the skin, heart, and muscles.
Lastly, similar to plasmodesmata in plant cells, gap junctions are the third type of direct junction found within animal cells. These junctions are channels between adjacent cells that allow for the transport of ions, nutrients, and other substances that enable cells to communicate. Structurally, however, gap junctions and plasmodesmata differ. Gap junctions develop when a set of six proteins (called connexins) in the plasma membrane arrange themselves in an elongated doughnut-like configuration called a connexon. When the pores (“doughnut holes”) of connexons in adjacent animal cells align, a channel between the two cells forms. Gap junctions are particularly important in cardiac muscle. The electrical signal for the muscle to contract is passed efficiently through gap junctions, which allows the heart muscle cells to contract in tandem.
Contributions and Attributions
- OpenStax College, Biology. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest...ol11448/latest . License : CC BY: Attribution
- extracellular matrix. Provided by : Wiktionary. Located at : http://en.wiktionary.org/wiki/extracellular_matrix . License : CC BY-SA: Attribution-ShareAlike
- proteoglycan. Provided by : Wiktionary. Located at : http://en.wiktionary.org/wiki/proteoglycan . License : CC BY-SA: Attribution-ShareAlike
- collagen. Provided by : Wiktionary. Located at : http://en.wiktionary.org/wiki/collagen . License : CC BY-SA: Attribution-ShareAlike
- OpenStax College, Connections between Cells and Cellular Activities. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest...e_04_06_01.jpg . License : CC BY: Attribution
- OpenStax College, Biology. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest...ol11448/latest . License : CC BY: Attribution
- OpenStax College, Biology. October 23, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest/?collection=col11448/latest . License : CC BY: Attribution
- plasmodesma. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/plasmodesma . License : CC BY-SA: Attribution-ShareAlike
- occludin. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/occludin . License : CC BY-SA: Attribution-ShareAlike
- connexon. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/connexon . License : CC BY-SA: Attribution-ShareAlike
- OpenStax College, Connections between Cells and Cellular Activities. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest/Figure_04_06_01.jpg . License : CC BY: Attribution
- OpenStax College, Connections between Cells and Cellular Activities. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest...e_04_06_02.jpg . License : CC BY: Attribution
- OpenStax College, Connections between Cells and Cellular Activities. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest...e_04_06_03.jpg . License : CC BY: Attribution
- OpenStax College, Connections between Cells and Cellular Activities. October 16, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44413/latest...e_04_06_04.jpg . License : CC BY: Attribution
Key Points
- Plasmodesmata are intercellular junctions between plant cells that enable the transportation of materials between cells.
- A tight junction is a watertight seal between two adjacent animal cells, which prevents materials from leaking out of cells.
- Desmosomes connect adjacent cells when cadherins in the plasma membrane connect to intermediate filaments.
- Similar to plasmodesmata, gap junctions are channels between adjacent cells that allow for the transport of ions, nutrients, and other substances.
Key Terms
- plasmodesma : A microscopic channel traversing the cell walls of plant cells and some algal cells, enabling transport and communication between them.
- connexon : An assembly of six connexins forming a bridge called a gap junction between the cytoplasms of two adjacent cells.
- occludin : Together with the claudin group of proteins, it is the main component of the tight junctions.


1.9: Scope Planning
You always want to know exactly what work has to be done before you start it. You have a collection of team members, and you need to know exactly what they’re going to do to meet the project’s objectives. The scope planning process is the very first thing you do to manage your scope. Project scope planning is concerned with the definition of all the work needed to successfully meet the project objectives. The whole idea here is that when you start the project, you need to have a clear picture of all the work that needs to happen on your project, and as the project progresses, you need to keep that scope up to date and written down in the project’s scope management plan.
Defining the Scope
You already have a head start on refining the project’s objectives in quantifiable terms, but now you need to plan further and write down all the intermediate and final deliverables that you and your team will produce over the course of the project. Deliverables include everything that you and your team produce for the project (i.e., anything that your project will deliver). The deliverables for your project include all of the products or services that you and your team are performing for the client, customer, or sponsor. They include every intermediate document, plan, schedule, budget, blueprint, and anything else that will be made along the way, including all of the project management documents you put together. Project deliverables are tangible outcomes, measurable results, or specific items that must be produced to consider either the project or the project phase completed. Intermediate deliverables, like the objectives, must be specific and verifiable.
All deliverables must be described in a sufficient level of detail so that they can be differentiated from related deliverables. For example:
- A twin engine plane versus a single engine plane
- A red marker versus a green marker
- A daily report versus a weekly report
- A departmental solution versus an enterprise solution
One of the project manager’s primary functions is to accurately document the deliverables of the project and then manage the project so that they are produced according to the agreed-on criteria. Deliverables are the output of each development phase, described in a quantifiable way.
Project Requirements
After all the deliverables are identified, the project manager needs to document all the requirements of the project. Requirements describe the characteristics of the final deliverable, whether it is a product or a service. They describe the required functionality that the final deliverable must have or specific conditions the final deliverable must meet in order to satisfy the objectives of the project. A requirement is an objective that must be met. The project’s requirements, defined in the scope plan, describe what a project is supposed to accomplish and how the project is supposed to be created and implemented. Requirements answer the following questions regarding the as-is and to-be states of the business: who, what, where, when, how much, and how does a business process work?
Requirements may include attributes like dimensions, ease of use, colour, specific ingredients, and so on. If we go back to the example of the company producing holiday eggnog, one of the major deliverables is the cartons that hold the eggnog. The requirements for that deliverable may include carton design, photographs that will appear on the carton, colour choices, etc.
Requirements specify what the final project deliverable should look like and what it should do. Requirements must be measurable, testable, related to identified business needs or opportunities, and defined to a level of detail sufficient for system design. They can be divided into six basic categories: functional, non-functional, technical, business, user, and regulatory requirements.
Functional Requirements
Functional requirements describe the characteristics of the final deliverable in ordinary non-technical language. They should be understandable to the customers, and the customers should play a direct role in their development. Functional requirements are what you want the deliverable to do.
Vehicle Example
If you were buying vehicles for a business, your functional requirement might be: “The vehicles should be able to take up to a one ton load from a warehouse to a shop.”
Computer System Example
For a computer system you may define what the system is to do: “The system should store all details of a customer’s order.”
The important point to note is that what is wanted is specified and not how it will be delivered.
Non-Functional Requirements
Non-functional requirements specify criteria that can be used to judge the final product or service that your project delivers. They are restrictions or constraints to be placed on the deliverable and how to build it. Their purpose is to restrict the number of solutions that will meet a set of requirements. Using the vehicle example, the functional requirement is for a vehicle to take a load from a warehouse to a shop. Without any constraints, the solutions being offered might result in anything from a small to a large truck. Non-functional requirements can be split into two types: performance and development.
To restrict the types of solutions, you might include these performance constraints:
- The purchased trucks should be American-made trucks due to government incentives.
- The load area must be covered.
- The load area must have a height of at least 10 feet.
Similarly, for the computer system example, you might specify values for the generic types of performance constraints:
- The response time for information is displayed on the screen for the user.
- The number of hours a system should be available.
- The number of records a system should be able to hold.
- The capacity for growth of the system should be built in.
- The length of time a record should be held for auditing purposes.
For the customer records example, the constraints might be:
- The system should be available from 9 a.m. to 5 p.m.Monday to Friday.
- The system should be able to hold 100,000 customer records initially.
- The system should be able to add 10,000 records a year for 10 years.
- A record should be fully available on the system for at least seven years.
One important point with these examples is that they restrict the number of solution options that are offered to you by the developer. In addition to the performance constraints, you may include some development constraints.
There are three general types of non-functional development constraints:
- Time : When a deliverable should be delivered
- Resource : How much money is available to develop the deliverable
- Quality : Any standards that are used to develop the deliverable, development methods, etc.
Technical Requirements
Technical requirements emerge from the functional requirements to answer the questions: how will the problem be solved this time and will it be solved technologically and/or procedurally? They specify how the system needs to be designed and implemented to provide required functionality and fulfill required operational characteristics.
For example, in a software project, the functional requirements may stipulate that a database system will be developed to allow access to financial data through a remote terminal. The corresponding technical requirements would spell out the required data elements, the language in which the database management system will be written (due to existing knowledge in-house), the hardware on which the system will run (due to existing infrastructure), telecommunication protocols that should be used, and so forth.
Business Requirements
Business requirements are the needs of the sponsoring organization, always from a management perspective. Business requirements are statements of the business rationale for the project. They are usually expressed in broad outcomes, satisfying the business needs, rather than specific functions the system must perform. These requirements grow out of the vision for the product that, in turn, is driven by mission (or business) goals and objectives.
User Requirements
User requirements describe what the users need to do with the system or product. The focus is on the user experience with the system under all scenarios. These requirements are the input for the next development phases: user-interface design and system test cases design.
Regulatory requirements
Regulatory requirements can be internal or external and are usually non-negotiable . They are the restrictions, licenses, and laws applicable to a product or business that are imposed by the government.
An Example of Requirements
Automated teller machines (ATMs) can be used to illustrate a wide range of requirements (Figure 9.1). What are some of the physical features of these machines, and what kinds of functions do they perform for the bank’s customers? Why did banks put these systems in place? What are the high-level business requirements?
The following represents one possible example of each type of requirement as they would be applied to a bank’s external ATM.
- ATM functional requirement: The system will enable the user to select whether or not to produce a hard-copy transaction receipt before completing a transaction.
- ATM non-functional requirement: All displays will be in white, 14-point Arial text on black background.
- ATM technical requirement: The ATM system will connect seamlessly to the existing customer’s database.
- ATM user requirement: The system will complete a standard withdrawal from a personal account, from login to cash, in less than two minutes.
- ATM business requirement: By providing superior service to our retail customers, Monumental Bank’s ATM network will allow us to increase associated service fee revenue by 10% annually on an ongoing basis.
- ATM regulatory requirement: All ATMs will connect to standard utility power sources within their civic jurisdiction, and be supplied with an uninterrupted power source approved by the company.
The effective specification of requirements is one of the most challenging undertakings project managers face. Inadequately specified requirements will guarantee poor project results.
Documenting requirements is much more than just the process of writing down the requirements as the user sees them; it should cover not only what decisions have been made, but why they have been made, as well. Understanding the reasoning that was used to arrive at a decision is critical in avoiding repetition. For example, the fact that a particular feature has been excluded, because it is simply not feasible, needs to be recorded. If it is not, then the project risks wasted work and repetition, when a stakeholder requests the feature be reinstated during development or testing.
Once the requirements are documented, have the stakeholders sign off on their requirements as a confirmation of what they desire.
While the project manager is responsible for making certain the requirements are documented, it does not mean that the project manager performs this task. The project manager enlists the help of all the stakeholders (business analysts, requirement analysts, business process owners, customers and other team members) to conduct the discussions, brain-storming, and interviews, and to document and sign off the requirements. The project manager is responsible only for enabling the process and facilitating it. If the project manager feels that the quality of the document is questionable, his or her duty is to stop the development process.
The project manager reviews the requirements, incorporates them into the project documentation library, and uses them as an input for the project plan.
Software Requirements Fundamentals
This section refers to requirements of “software” because it is concerned with problems to be addressed by software. A software requirement is a property that must be exhibited by software developed or adapted to solve a particular problem. The problem may be to automate part of a task of someone who will use the software, to support the business processes of the organization that has commissioned the software, to correct shortcomings of existing software, to control a device, etc. The functioning of users, business processes, and devices is typically complex. Therefore, the requirements on particular software are typically a complex combination of requirements from different people at different levels of an organization and from the environment in which the software will operate.
An essential property of all software requirements is that they be verifiable. It may be difficult or costly to verify certain software requirements. For example, verification of the throughput requirement on a call centre may necessitate the development of simulation software. Both the software requirements and software quality personnel must ensure that the requirements can be verified within the available resource constraints.
Requirements have other attributes in addition to the behavioural properties that they express. Common examples include a priority rating to enable trade-offs in the face of finite resources and a status value to enable project progress to be monitored. Typically, software requirements are uniquely identified so that they can be monitored over the entire software life cycle.
Measuring Requirements
As a practical matter, it is typically useful to have some concept of the volume of the requirements for a particular software product. This number is useful in evaluating the size of a change in requirements, in estimating the cost of a development or maintenance task, or simply in using it as the denominator in other measurements (see Table 9.1).
| Property | Measure |
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| Speed |
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| Size |
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| Ease of use |
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| Reliability |
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| Robustness |
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| Portability |
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Scope Inputs
The project manager gathers initial project facts from the project charter. In addition, background information on the stakeholder’s workplace, existing business model and rules, etc. assist in creating the vision of the final product/service, and consequently, the project scope (see Figure 9.2).
Techniques
Certainly being a seasoned project manager broadens the repertoire of one’s scope planning techniques. An experienced project manager can draw on past experiences with like projects to determine the work that is realistically doable, given time and cost constraints, for a current project. Communication and negotiation skills are a “must-have” as well. Project managers need to educate stakeholders about the project impacts of some requirements. Adding complexity to a project may require more staff, time, and/or money. It may also have an impact on project quality. Some aspects of the project may be unfeasible – stakeholders need to know this so they can adjust their vision or prepare for future challenges.
Gathering requirements is part of scope definition, and it can be done using one or more of following techniques:
- Interviews
- Focus groups
- Facilitated groups such as JAD (joint application development)
- Group creativity techniques: brainstorming, nominal groups, delphi, mind map, affinity diagnostics
- Prototyping
- Observation
- Questions and surveys
- Group decision-making techniques: unanimity, majority, plurality, dictatorship
Requirements Traceability Matrix
The requirements traceability matrix is a table that links requirements to their origin and traces them throughout the project life cycle. The implementation of a requirements traceability matrix helps ensure that each requirement adds business value by linking it to the business and project objectives. It provides a means to track requirements throughout the project life cycle, helping to ensure that requirements approved in the requirements documentation are delivered at the end of the project. Finally, it provides a structure for managing changes to the product scope. This process includes, but is not limited to, tracking:
- Requirements to business needs, opportunities, goals, and objectives
- Requirements to project objectives
- Requirements to project scope/work breakdown structure deliverables
- Requirements to product design
- Requirements to product development
- Requirements to test strategy and test scenarios
- High-level requirements to more detailed requirements
Attributes associated with each requirement can be recorded in the requirements traceability matrix. These attributes help to define key information about the requirement. Typical attributes used in the requirements traceability matrix may include a unique identifier, a textual description of the requirement, the rationale for inclusion, owner, source, priority, version, current status (such as active, cancelled, deferred, added, approved), and date completed. Additional attributes to ensure that the requirement has met stakeholders’ satisfaction may include stability, complexity, and acceptance criteria.
Matrix Fields
These are suggestions only and will vary based on organizational and project requirements.
- A unique identification number containing the general category of the requirement (e.g., SYSADM) and a number assigned in ascending order (e.g., 1.0, 1.1, 1.2)
- Requirement statement
- Requirement source (conference, configuration control board, task assignment, etc.)
- Software requirements specification/functional requirements document paragraph number containing the requirement
- Design specification paragraph number containing the requirement
- Program module containing the requirement
- Test specification containing the requirement test
- Test case number(s) where requirement is to be tested (optional)
- Verification of successful testing of requirements
- Modification field (If a requirement was changed, eliminated, or replaced, indicate disposition and authority for modification.)
- Remarks
Work Breakdown Structure
Now that we have the deliverables and requirements well defined, the process of breaking down the work of the project via a work breakdown structure (WBS) begins. The WBS defines the scope of the project and breaks the work down into components that can be scheduled, estimated, and easily monitored and controlled. The idea behind the WBS is simple: you subdivide a complicated task into smaller tasks, until you reach a level that cannot be further subdivided. Anyone familiar with the arrangements of folders and files in a computer memory or who has researched their ancestral family tree should be familiar with this idea. You stop breaking down the work when you reach a low enough level to perform an estimate of the desired accuracy. At that point, it is usually easier to estimate how long the small task will take and how much it will cost to perform than it would have been to estimate these factors at the higher levels. Each descending level of the WBS represents an increased level of detailed definition of the project work.
WBS describes the products or services to be delivered by the project and how they are decomposed and related. It is a deliverable-oriented decomposition of a project into smaller components. It defines and groups a project’s discrete work elements in a way that helps organize and define the total work scope of the project.
A WBS also provides the necessary framework for detailed cost estimating and control, along with providing guidance for schedule development and control.
Overview
WBS is a hierarchical decomposition of the project into phases, deliverables, and work packages. It is a tree structure, which shows a subdivision of effort required to achieve an objective (e.g., a program, project, and contract). In a project or contract, the WBS is developed by starting with the end objective and successively subdividing it into manageable components in terms of size, duration, and responsibility (e.g., systems, subsystems, components, tasks, subtasks, and work packages), which include all steps necessary to achieve the objective.
The WBS creation involves:
- Listing all the project outputs (deliverables and other direct results)
- Identifying all the activities required to deliver the outputs
- Subdividing these activities into subactivities and tasks
- Identifying the deliverable and milestone(s) of each task
- Identifying the time usage of all the resources (personnel and material) required to complete each task
The purpose of developing a WBS is to:
- Allow easier management of each component
- Allow accurate estimation of time, cost, and resource requirements
- Allow easier assignment of human resources
- Allow easier assignment of responsibility for activities
Example of a WBS
If I want to clean a room, I might begin by picking up clothes, toys, and other things that have been dropped on the floor. I could use a vacuum cleaner to get dirt out of the carpet. I might take down the curtains and take them to the cleaners, and then dust the furniture. All of these tasks are subtasks performed to clean the room. As for vacuuming the room, I might have to get the vacuum cleaner out of the closet, connect the hose, empty the bag, and put the machine back in the closet. These are smaller tasks to be performed in accomplishing the subtask called vacuuming. Figure 9.3 shows how this might be portrayed in WBS format.
It is very important to note that we do not worry about the sequence in which the work is performed or any dependencies between the tasks when we do a WBS. That will be worked out when we develop the schedule. For example, under 3.0 Vacuum, it would be obvious that 3.3 Vacuum carpet would be performed after 3.4 Connect hose and plug! However, you will probably find yourself thinking sequentially, as it seems to be human nature to do so. The main idea of creating a WBS is to capture all of the tasks, irrespective of their order. So if you find yourself and other members of your team thinking sequentially, don’t be too concerned, but don’t get hung up on trying to diagram the sequence or you will slow down the process of task identification. A WBS can be structured any way it makes sense to you and your project. In practice, the chart structure is used quite often but it can be composed in outline form as well (Figure 9.4).
You’ll notice that each element at each level of the WBS in both figures is assigned a unique identifier. This unique identifier is typically a number, and it’s used to sum and track costs, schedules, and resources associated with WBS elements. These numbers are usually associated with the corporation’s chart of accounts, which is used to track costs by category. Collectively, these numeric identifiers are known as the code of accounts.
There are also many ways you can organize the WBS. For example, it can be organized by either deliverable or phase. The major deliverables of the project are used as the first level in the WBS. For example, if you are doing a multimedia project the deliverables might include producing a book, CD, and a DVD (Figure 9.5).
Many projects are structured or organized by project phases (Figure 9.6). Each phase would represent the first level of the WBS and their deliverables would be the next level and so on.
The project manager is free to determine the number of levels in the WBS based on the complexity of the project. You need to include enough levels to accurately estimate project time and costs but not so many levels that are difficult to distinguish between components. Regardless of the number of levels in a WBS, the lowest level is called a work package.
Work packages are the components that can be easily assigned to one person or a team of people, with clear accountability and responsibility for completing the assignment. The work-package level is where time estimates, cost estimates, and resource estimates are determined.
100 Percent Rule
The 100 percent rule is the most important criterion in developing and evaluating the WBS. The rule states that each decomposed level (child) must represent 100 percent of the work applicable to the next higher (parent) element. In other words, if each level of the WBS follows the 100 percent rule down to the activities, then we are confident that 100 percent of the activities will have been identified when we develop the project schedule. When we create the budget for our project, 100 percent of the costs or resources required will be identified.
Scope Statement
Scope statements may take many forms depending on the type of project being implemented and the nature of the organization. The scope statement details the project deliverables and describes the major objectives. The objectives should include measurable success criteria for the project.
A scope statement captures, in very broad terms, the product of the project: for example, “development of a software-based system to capture and track orders for software.” A scope statement should also include the list of users using the product, as well as the features in the resulting product.
As a baseline scope statements should contain:
- The project name
- The project charter
- The project owner, sponsors, and stakeholders
- The problem statement
- The project goals and objectives
- The project requirements
- The project deliverables
- The project non-goals (what is out of scope)
- Milestones
- Cost estimates
In more project-oriented organizations, the scope statement may also contain these and other sections:
- Project scope management plan
- Approved change requests
- Project assumptions and risks
- Project acceptance criteria
Image Descriptions
Figure 9.2 image description: A project manager develops a Scope Management Plan by taking the project charter, organizational memory, and the project plan and applying the following techniques and tools:
- Calls on past project experience
- Uses scope management templates (SOS, WBS, Scope Management Plan)
- Uses Communication skills (for negotiating with and educating clients)
Figure 9.3 image description:
0.0 Clean Room
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1.0 Mop floor.
- 1.1 Get mop and bucket out.
- 1.2 Mix cleaner with water in bucket.
- 1.3 Rinse out bucket and mop.
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2.0 Dust
- 2.1 Coffee table
- 2.2 Blinds
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3.0 Vacuum
- 3.1 Get vacuum out of closet
- 3.2 Vacuum carpet
- 3.3 Empty bag
- 3.4 Connect hose and plug
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4.0 Pick up floor
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4.1 Toys
- 4.1.1 Put toys in box
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4.2 Clothes
- 4.2.1 Hang up in closet
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4.1 Toys
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5.0 Clean curtains
- 5.1 Remove curtains
- 5.2 Take to cleaners
- 5.3 Hang curtains
Text Attributions
This chapter of Project Management is a derivative of the following texts:
- Project Management by Merrie Barron and Andrew Barron . © CC BY (Attribution) .
- Project Management/PMBOK/Scope Management and Development Cooperation Handbook/Designing and Executing Projects/Detailed Planning or design stage by Wikibooks. © CC BY-SA (Attribution-ShareAlike) .
- Requirements Traceability Matrix by DHWiki. © CC BY-NC-ND (Attribution-NonCommercial-NoDerivatives)
- Work Breakdown Structure by Wikipedia. © CC BY-SA (Attribution-ShareAlike) .
- 100 Percent Rule by Pabipedia. © CC BY-SA (Attribution-ShareAlike) .
Media Attributions
- ATM by megawatts86 © CC BY-SA (Attribution ShareAlike)
- Scope Management IO by Flaming Sevens adapted by Josie Gray © Public Domain
- WBS Cleaning Room by Barron & Barron Project Management for Scientists and Engineers © CC BY (Attribution)
- WBS Outline – Clean Room by Barron & Barron Project Management for Scientists and Engineers © CC BY (Attribution)
- Multimedia Project WBS by Barron & Barron Project Management for Scientists and Engineers © CC BY (Attribution)
- WBS Project Phases by Barron & Barron Project Management for Scientists and Engineers © CC BY (Attribution)


8.11.3: Eukaryotic Gene Regulation
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- Last updated
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- Ying Liu
- City College of San Francisco
Like prokaryotes, transcriptional regulation in eukaryotes involves both cis -elements and trans -factors, only there are more of them and they interact in a more complex way. A diagram of a typical eukaryotic gene, including several types of cis -elements, is shown in Figure \(\PageIndex{7}\).
Proximal Regulatory Sequences
As in prokaryotes the RNA polymerase binds to the gene at its promoter to begin transcription. In eukaryotes, however, RNApol is part of a large protein complex that includes additional proteins that bind to one or more specific cis -elements in the promoter region, including GC-rich boxes , CAAT boxes , and TATA boxes . High levels of transcription require both the presence of this protein complex at the promoter, as well as their interaction with other trans -factors described below. The approximate position of these elements relative to the transcription start site ( + 1) is shown in Figure \(\PageIndex{7}\), but it should be emphasized that the distance between any of these elements and the transcription start site can vary, but are typically within ~200 base pairs of the start of transcription. This contrasts the next set of elements.
Distal Regulatory elements
Even more variation is observed in the position and orientation of the second major type of cis -regulatory element in eukaryotes, which are called enhancer elements . Regulatory trans -factor proteins called transcription factors bind to enhancer sequences, then, while still bound to DNA, these proteins interact with RNApol and other proteins at the promoter to enhance the rate of transcription. There are a wide variety of different transcription factors and each recognizes a specific DNA sequence (enhancer element) to promote gene expression in the adjacent gene under specific circumstances. Because DNA is a flexible molecule, enhancers can be located near (~100s of bp) or far (~10K of bp), and either upstream or downstream, from the promoter (Figures \(\PageIndex{7}\) and \(\PageIndex{8}\)).
Example 1: Drosophila yellow gene
The yellow gene of Drosophila provides an example of the modular nature of enhancers. This gene encodes an enzyme in the pathway that produces a dark pigment in the insect’s exoskeleton. Mutants have a yellow cuticle rather than the wild type darker pigmented cuticle. (Why call the gene “yellow”: recall that genes are often named after their mutant phenotype.) Figure \(\PageIndex{9}\) shows three enhancer elements (left side - wing, body, mouth), each binds a different tissue specific transcription factor to enhancer transcription of yellow + in that tissue and makes the pigment. So, the wing cells will have a transcription factor that binds to the wing enhancer to drive expression; likewise in the body and mouth cells. Thus, specific combinations of cis -elements and trans -factors control the differential, tissue-specific expression of genes. This type of combinatorial action of enhancers is typical of the transcriptional activation of most eukaryotic genes: specific transcription factors activate the transcription of target genes under specific conditions.
While enhancer sequences promote expression, there is an oppositely acting type of element, called silencers . These elements function in much the same manner, with transcription factors that bind to DNA sequences, but they act to silence or reduce transcription from the adjacent gene.
Again, a gene’s expression profile (transcription level, tissue specific, temporal specific) is a combination of various enhancer and silencer elements.
Example 2: Gal4-UAS system from yeast – a genetic tool
Genetic researchers have taken advantage of a yeast distal enhancer sequence to make the GAL4-UAS system , a powerful technique for studying the expression of genes in other eukaryotes. It relies on two parts: a “ driver ” and a “ responder ” (Figure \(\PageIndex{10}\)). The driver part is a gene encoding a yeast transcriptional activator protein called Gal4. It is separate from the responder part, which contains the enhancer sequence, or upstream activation sequence (UAS, as it is called in yeast) to which the Gal4 protein specifically binds. This UAS is placed upstream (using genetic engineering) from a promoter transcribing a reporter gene, or other gene of interest, such as GFP (green fluorescent protein).
Both parts must be present in the same cell for the system to express the responder gene. If the driver is absent, the responder product will not be expressed. However, both are in the same cell (or organism) the pattern of expression of the driver part will induce the responder part’s expression in the same pattern.
This system works is a variety of eukaryotes, including humans. It has been especially well exploited in Drosophila where 100’s (1,000’s ? ) of differently expressing driver lines are available. These lines permit the tissue specific expression of any responder gene to examine its effect on development.


1.1.4: Competitive Advantage
Can Information Systems Bring Competitive Advantage?
It has always been the assumption that the implementation of information systems will, in and of itself, bring a business competitive advantage. After all, if installing one computer to manage inventory can make a company more efficient, won’t installing several computers to handle even more of the business continue to improve it?
In 2003, Nicholas Carr wrote an article in the Harvard Business Review that questioned this assumption. The article, entitled “IT Doesn’t Matter,” raised the idea that information technology has become just a commodity. Instead of viewing technology as an investment that will make a company stand out, it should be seen as something like electricity: It should be managed to reduce costs, ensure that it is always running, and be as risk-free as possible.
As you might imagine, this article was both hailed and scorned. Can IT bring a competitive advantage? It sure did for Walmart (see sidebar). We will discuss this topic further in chapter 7.
Sidebar: Walmart Uses Information Systems to Become the World’s Leading Retailer
Walmart is the world’s largest retailer, earning $15.2 billion on sales of $443.9 billion in the fiscal year that ended on January 31, 2012. Walmart currently serves over 200 million customers every week, worldwide. [5] Walmart’s rise to prominence is due in no small part to their use of information systems.
One of the keys to this success was the implementation of Retail Link, a supply-chain management system. This system, unique when initially implemented in the mid-1980s, allowed Walmart’s suppliers to directly access the inventory levels and sales information of their products at any of Walmart’s more than ten thousand stores. Using Retail Link, suppliers can analyze how well their products are selling at one or more Walmart stores, with a range of reporting options. Further, Walmart requires the suppliers to use Retail Link to manage their own inventory levels. If a supplier feels that their products are selling out too quickly, they can use Retail Link to petition Walmart to raise the levels of inventory for their products. This has essentially allowed Walmart to “hire” thousands of product managers, all of whom have a vested interest in the products they are managing. This revolutionary approach to managing inventory has allowed Walmart to continue to drive prices down and respond to market forces quickly.
Today, Walmart continues to innovate with information technology. Using its tremendous market presence, any technology that Walmart requires its suppliers to implement immediately becomes a business standard.
Depending on which products and services a business offers, just as Nicholas mentioned, Information systems could be a utility as water and electricity that is required in order for you to succeed as a business in general. Walmart’s growth had emerged in a time slot that business techniques and information technology had been still evolving, but it can be assumed that a vast majority of competing businesses achieved the same results as Walmart that may be unreported.
Just as at one point, having an Iphone or a Tesla was a huge sign of someone with wealth and or luck. Having those items is as common as drinking a water bottle. Businesses will need to get into the habit of managing their information systems for the ever changing demands of society and its clientele in order to maintain success. Putting a huge level of pressure on the technology used or types of practices that are implemented may introduce a certain level of growth or increase in sales, But it can not compare to a business that succeeds based on reputation or quality of service.


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3.1: The Work - Energy Theorem
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For a large number of applications in mechanics, we are not interested in how a force causes the direction of motion of an object to change – we only care about how that force changes the speed of the object.
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3.2: Work and Energy for Collections of Particles
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We discover that a system comprised of a collection of many moving particles can be reimagined as a single system that has both a collective kinetic energy and an internal energy.
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3.3: Conservative and Non-Conservative Forces
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We categorize forces according to the dependence of the work they perform on the path that the effected particles follow.
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3.4: Energy Accounting with Conservative Forces: Potential Energy
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We introduce a useful shortcut to avoid complicated work calculations for conservative forces.
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3.5: Energy Accounting with Non-Conservative Forces: Thermal Energy
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We now put together what we have learned about energy to give us a powerful toolbox for solving problems in the macroscopic world.
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3.6: Mechanical Advantage and Power
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We will now take a closer look at simple machines from the perspective of work-energy, and discuss the rate at which work is performed.
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3.7: Energy Diagrams
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An energy diagram provides us a means to assess features of physical systems at a glance. We will examine a couple of simple examples, and then show how it can be used for more advanced cases in physics and chemistry. It's important to understand that there is no new physics in here – what we have learned so far now is simply represented diagrammatically, making it easier in some cases to see the "big picture" of a physical system.
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Sample Problems
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Image used with permission (CC BY-SA-NC; anonymous).


16.6: Summary
16.1 The Pain Process
Pain can be classified and described in many different ways. The duration, location, and cause are all important factors when assessing and treating pain. The physiologic process of pain describes how the brain is alerted to painful stimuli and how it can modify and adjust the amount of pain that is felt in the body. Biological, psychological, and social factors can affect the perception of pain and impact how patients react. The central nervous system can also determine which pain signals are allowed through to the brain. This gate control theory can help nurses understand how pain is perceived under different circumstances.
Nurses must be aware of the factors that can affect pain and patients’ perceptions of pain. One patient may perceive pain differently than another patient does, but both are right in their assessment. Nurses must accept the pain as whatever the patient says it is and individualize pain management strategies for each patient.
16.2 Responses to Pain
Physiologic, behavioral, and emotional responses to pain are the brain’s way of keeping the body safe in signs of danger. The sympathetic and parasympathetic nervous system s allow the body to initiate responses that either fight or run away from a perceived threat. Behaviors, emotions, and vital sign changes such as elevated blood pressure, heart rate, and respiratory rate can all be ways that patients express signs of pain.
Behavioral and emotional responses to pain can vary among patients. Some patients may vocalize their pain or express body movements and social interactions that demonstrate pain. Some patients may experience negative emotions such as fear and anxiety when dealing with pain. Nurses must be aware of all physiologic response s to pain and know that these responses can vary greatly among patients. Physiologic responses to pain are involuntary and are often the first reaction a patient will have to pain. These responses can help healthcare providers assess pain and develop effective strategies for managing pain.
16.3 Factors Affecting Pain
There are many factors that play a role in pain. Psychosocial factors can influence a patient’s perspective on pain. A patient who associates pain with trauma may have a hard time coping with chronic pain . Physiological factors such as developmental level and age can change a patient’s perception and expression of pain over time. A patient’s psychological view of pain can influence how effective pain management strategies can be. A patient who catastrophizes their pain may have worse outcomes than a patient who expects their pain medication to be effective. Nurses play an important role in educating patients about these factors. Patients’ awareness of these factors and their effect on pain can make a big difference in pain management outcomes.
16.4 Pain Assessment
A comprehensive pain assessment must include subjective and objective data . Collecting subjective data involves choosing an appropriate pain rating scale, asking open-ended assessment questions, and accepting the pain is whatever the patient says it is. Collecting objective data involves performing a physical assessment, measuring vital signs, and assessing nonverbal behavior. Each pain assessment may have different ways of collecting subjective and objective data. The nurse should choose the pain assessment tools that are appropriate for each patient.
Pain assessments, interventions, and evaluations should be performed and documented in a timely manner to ensure adequate pain relief is achieved. Documentation of pain management ensures the patient receives timely and effective treatment. Pain management strategies cannot be deemed effective without comprehensive assessment and documentation. Pain management is an ongoing concern for patient care, and a quality pain assessment is the first step to effective pain relief.
16.5 Pain Management
There are many different types of interventions that can be used for pain management. Pain management should always include patient involvement and a combination of nonpharmacological and pharmacological interventions. Nurses have a responsibility to provide adequate pain management to all patients and will encounter pain in all types of healthcare settings.
Pharmacological therapy can be very effective in managing pain but must be used with caution. There are many risks and side effects, especially with opioid analgesics. Nurses must be aware of the risks and ensure patients are educated on appropriate dosing and monitoring when taking these medications. Patient-controlled analgesia (PCA) can also be an effective way to manage pain and involve the patient in their care. However, PCA is also not without risks. Nurses must be vigilant when monitoring a patient receiving PCA and ensure the patient meets criteria to be able to understand how to use PCA.
Non pharmacological therapy can also be an effective pain management strategy, especially when paired with pharmacological therapy. Interventions such as physical therapy , guided imagery , and distraction can be effective pain management strategies without the same risks as pharmacological therapy. Nonpharmacological pain interventions have been shown to be effective in treating all types of pain and allow patients to avoid the side effects and risk of chronic issues such as addiction and overdose from opioid analgesics. Being aware of all types of pain management strategies is essential for all nurses and helps nurses effectively manage pain.


5.1: Objectives
After completing this chapter, you should
Solving Equations
- be able to identify various types of equations
- understand the meaning of solutions and equivalent equations
- be able to solve equations of the form \(x+a=b\) and \(x−a=b\).
- be familiar with and able to solve linear equation
Solving Equations of the Form \(ax=b\) and \(\dfrac{x}{a}=b\)
- understand the equality property of addition and multiplication
- be able to solve equations of the form \(ax=b\) and \(\dfrac{x}{a}=b\)
Further Techniques in Equation Solving
- be comfortable with combining techniques in equation solving
- be able to recognize identities and contradictions
Applications I - Translating from Verbal to Mathematical Expressions
- be able to translate from verbal to mathematical expressions
Applications II - Solving Problems
- be able to solve various applied problems
Linear Inequalities in One Variable
- understand the meaning of inequalities
- be able to recognize linear inequalities
- know, and be able to work with, the algebra of linear inequalities and with compound inequalities
Linear Inequalities in Two Variables
- be able to identify the solution of a linear equation in two variables
- know that solutions to linear equations in two variables can be written as ordered pairs


9.4: Assignment- Memo on Diversity at Sun City Boards
Scenario
Tom founded Sun City Boards out of his passion for surfing and has hired employees who have also expressed their surfing interest. Through the help and advice of his friend, he has been making changes to the business operation, including hiring new people. Sun City Boards now employs 17 people, and Tom plans to hire another 8 to 10 in the near future. Tom is unaware of and unaccustomed to the concepts of culture and diversity in business, and his initial hires primarily stemmed from his immediate friend group and local surfers. Additionally, looking at the org chart, you find that while there are several people of color and women in the organization, a majority of leadership roles are filled by white men. You have decided to advise Tom to consider a more diverse population of people for his next hires and any upcoming promotions.
Preparation
In this assignment, you will review aspects of culture and diversity for Sun City. In your readings on Culture and Diversity, you learned to define culture in a business and the impact of a diverse workforce on business success.
You will look for ways their culture can be evaluated and then summarize your findings and advice in a memo to CEO Tom Wilson. The following steps will help you prepare for your written assignment:
- Carefully consider the artifacts, values, and assumptions that might be observed at an organization like Sun City Boards.
- Think of how a diverse workforce would impact the Sun City business.
Your Task
- Identify specific artifacts you might look for at Sun City to evaluate their diversity, using at least three specific examples or topics covered in the reading. For example, since Sun City is in a change mode, you could identify the impact of role modeling on the employees.
- Finally, write a three-paragraph (minimum) memo addressed to Sun City CEO Tom Wilson. Explain why diversity is important to his business and how he might go about evaluating the culture and diversity of Sun City Boards. You must support your advice with the three specific examples you identified in the previous step. If you’re not familiar with a Memo style, you can click this link to view a sample memo . (Note: Your memo does not need to contain every section included in the sample memo. Just be sure to include the date, recipient, sender, subject, and at least three paragraphs explaining to Tom Wilson why diversity is important to his business and how to evaluate it.) Be sure to address the CEO properly, and write to him as a concerned executive. In addition to the text, you are encouraged to research culture and diversity using reliable and properly cited Internet resources. You may also draw from your personal work experience with appropriate examples to support your references.
Contributors and Attributions
- Assignment: Memo on Diversity at Sun City Boards. Authored by : Betty Fitte and Lumen Learning. License : CC BY: Attribution


4.2: Open Enrollment
What is Open Enrollment?
An open enrollment period is a window of time that happens once a year — typically in the fall — when you can sign up for health insurance, adjust your current plan or cancel your plan. It’s usually limited to a few weeks. If you miss it, you may have to wait until the next open enrollment period to make any changes.
Qualifying Life Events
As with most things, there are exceptions! In this case, they are called qualifying life events. A qualifying life event is a life-changing situation — sometimes planned, sometimes unexpected — that can impact you and your health insurance. Experiencing a significant life change may allow you to change your health plan outside of the annual enrollment period (also called open enrollment ).
Qualifying life events include, but are not limited to:
- Marriage or divorce
- Having or adopting a baby
- Death of someone who shares your health plan
- Moving to a new area
- Earning U.S. citizenship
- Turning 26, or turning 65
- Change of employment status
- Loss of health insurance for other reasons


2.6: Outcome- Identifying Minerals
Identify and classify common rock forming minerals.
The solid earth is made of rocks, which are made of minerals. To understand rocks you need to become familiar with minerals and how they are identified. This outcome gives you the background needed to understand the terms used in identifying minerals.
This section will introduce you to minerals. You will learn the various techniques used by geologists to identify and classify minerals.
What You’ll Learn to Do
- Identify minerals based on their physical characteristics.
- Sort minerals into the correct mineral class.
Learning Activities
The learning activities for this section include the following:
- Reading: Physical Characteristics of Minerals
- Reading: Classifying Minerals
- Self Check: Identifying Minerals
Contributors and Attributions
CC licensed content, Original
- Authored by : Lumen Learning and SBCTC. License : CC BY: Attribution
CC licensed content, Shared previously
- Basics - Minerals. Authored by : Ralph L. Dawes and Cheryl D. Dawes. Provided by : Wenatchee Valley College. Located at : http://commons.wvc.edu/rdawes/G101OCL/Basics/minerals.html . Project : Geology 101 - Introduction to Physical Geology. License : CC BY: Attribution


3.4: Algebra Tips and Tricks Part VI (Logarithms)
Logarithms
A logarithm is the inverse function to an exponential function. For example, for the exponential function \(y = 2^x\), if we have an input of \(x = 6\), we get an output of \(y = 64\), and we write \(64 = 2^6\). The logarithmic function \(y = \log_2(x)\) is the reverse of this. We swap the input and the output, so now \(x = 64\) and \(y = 6\). We see \(6 = \log_2(64)\).
In calculus, we will mostly use the exponential function \(e^x\) and its inverse, \(\ln(x)\). Below are some important formulas:
\[\begin{align*} e^{\ln(x)} & = x \\ \ln(e^x) & = x \\ \ln(x) + \ln(y) & = \ln(xy) \\ \ln(x) - \ln(y) & = \ln\left(\frac{x}{y}\right) \\ a \ln(x) & = \ln(x^a) \end{align*}\]
Examples:
There are two ways to do this one. First, we can bring down the exponent of two down in front \(\ln(x^2) = 2 \ln(x)\). Then can combine the like terms of \(2\ln(x)\) and \(\ln(x)\):
\[\begin{align*} \ln(x^2) - \ln(x) & = 2 \ln(x) - \ln(x) \\ & = \boxed{\ln(x)} \end{align*}\]
Alternatively, we can rewrite the subtraction as a division, like so:
\[\begin{align*} \ln(x^2) - \ln(x) & = \ln\left(\frac{x^2}{x}\right) \\ & = \boxed{\ln(x)} \end{align*}\]
Either way we get the same answer!
First, we rewrite the multiplication using addition. Then we can simply from there.
\[\begin{align*} \ln(e^3 x^4) - 3 \ln(x) & = \ln(e^3) + \ln(x^4) - 3 \ln(x)\\ & = 3 + 4 \ln(x) - 3 \ln(x) \\ & = \boxed{3 + \ln(x)} \end{align*}\]
We know
, so
.
We can rewrite all the products and divisions as addition and subtraction:
\[\begin{align*} \ln\left(\frac{\sqrt{x} y}{z^3}\right) - \ln\left(\frac{z}{\sqrt{x} y^3}\right) & = \ln(\sqrt{x}) + \ln(y) - \ln(z^3) - [\ln(z) - \ln(\sqrt{x}) - \ln(y^3)] \\ & = \frac{1}{2} \ln(x) + \ln(y) - 3 \ln(z) - \ln(z) + \frac{1}{2} \ln(x) + 3 \ln(y) \\ & = \boxed{\ln(x) + 4 \ln(y) - 4 \ln(z)}. \end{align*}\]