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.
Period refers to the time that it takes to do something. When an event occurs repeatedly, then we say that the event is periodic and refer to the time for the event to repeat itself as the period. The period of a wave is the time for a particle on a medium to make one complete vibrational cycle. Period, being a time, is measured in units of time such as seconds, hours, days or years. The period of orbit for the Earth around the Sun is approximately 365 days; it takes 365 days for the Earth to complete a cycle.