ANATOMY

Detailed explanation-1: -Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein.

Detailed explanation-2: -The amino acids link together with peptide bonds and become proteins. Then, the forces of other amino acids and the effects of their R-groups fold the protein into specific three-dimensional shapes.

Detailed explanation-3: -The 20 amino acids found in proteins. Both three-letter and one-letter abbreviations are listed. As shown, there are equal numbers of polar and nonpolar side chains.

Detailed explanation-4: -Both animal and plant proteins are made up of about 20 common amino acids. The proportion of these amino acids varies as a characteristic of a given protein, but all food proteins-with the exception of gelatin-contain some of each. Amino nitrogen accounts for approximately 16% of the weight of proteins.

Detailed explanation-5: -The best sources of essential amino acids are animal proteins such as meat, eggs, and poultry. However, some plant foods, such as the soy products edamame and tofu, contain all nine essential amino acids. This means they are “complete” sources of protein ( 2, 3 ).