Proteins are probably the most versatile of all the organic molecules, making up many structures and executing various functions within organisms. Building blocks called amino acids make up proteins. About 20 different amino acids combine to form all of the various types of proteins on Earth. These amino acids all have almost the exact same composition; the only difference is the R group, which differs in each of the amino acids and gives them their uniqueness.
duration - the period of time during which something continues. continuance. period, period of time, time period - an amount of time; a time period of 30 years; hastened the period of time of his recovery; Picasso's blue period. clocking - the time taken to traverse a measured course; it was a world record clocking.
The period of the object's motion is defined as the time for the object to complete one full cycle. Being a time, the period is measured in units such as seconds, milliseconds, days or even years. The standard metric unit for period is the second. An object in periodic motion can have a long period or a short period. For instance, a pendulum bob tied to a 1-meter length string has a period of about 2.0 seconds. For comparison sake, consider the vibrations of a piano string that plays the middle C note (the C note of the fourth octave).