Learn about the functions of proteins. Explains protein structure and chemical importance.
Proteins are nutrients that are vital to health. They are used to make skin and muscles, and are catalysts (they aid chemical reactions) in both plants and animals. Foods that are protein rich include eggs, meat, cheese, soybeans, and fish.
The monomer units (basic building blocks) of proteins are amino acids. There are twenty amino acids, which can form various combinations to make millions of different proteins. When two amino acids bond, they form a dipeptide. When three or more bond, they form a polypeptide.
Proteins are composed of one or more polypeptides. These proteins become bent and folded upon themselves as a result of reacting. One protein is a straight line, two is a curved line, three is a small blob, and four is bigger blob. This is not a scientific way of describing it, but it's what scientists see when they examine proteins on a molecular level. These proteins are several different amino acids, combined. As few as two can make up a protein, but many more can be involved. This is due to the fact that there are so many different proteins.
Amino acids contain the elements hydrogen, oxygen, carbon, and nitrogen. They are made up of four groups. In the center is a single carbon atom to which three other groups bond. One group is called the carboxyl group, and the molecule it contains is -COOH. Another group is called the amino group, and it contains -NH2. The last group is called the R group. This is how we distinguish one amino acid from another. The R group may be as simple as H or it may be as complex as CH3. The differences in the R groups give the proteins different shapes, which then perform many different roles in living things.
Proteins make up most enzymes. As mentioned earlier, these are necessary in chemical reactions within the human body. It fits in with a substrate (solution being catalyzed) on a molecular level. It then reduces the amount of energy needed for a chemical reaction. This is one of protein's most important functions, as cells could not survive without it.
Once enzymes have acted as a catalyst, they release byproducts of the reaction. However, they remain unchanged and can continue to catalyze such reactions for quite awhile. The only circumstances under which they would be unable to continue catalyzing is if they underwent a change in temperature or pH. This would cause it to change shape, and it would no longer fit with the substrate.
Steady pH and temperature are very important to proteins and, indeed, everything from a molecular level on up. They are required for steadiness (called homeostasis) in all organisms. This is what allows life and all its processes to be carried out. Without these stable conditions, proteins could not function properly. Nor could many other processes, and we would die. If pH was interrupted, it could cause too much acid to be produced which could also have a negative effect. Proteins often act as catalysts in these substances.
