What are amino acids that must be obtained from the diet because the body cannot synthesize them?

• A. Nitrogen base
• B. Essential amino acids
• C. Codons
• D. mRNA

Answer: (B)

The concept here is that some amino acids cannot be made by the body in enough amounts, so they must come from food. These are called essential amino acids. The body can synthesize the others on its own, so they don’t have to be obtained strictly through diet. Examples of essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine (arginine is essential for children, but not typically listed as essential for healthy adults). The other terms refer to components of genetic material rather than dietary requirements: a nitrogen base is part of nucleotides in DNA/RNA, codons are three-nucleotide sequences in mRNA that code for amino acids, and mRNA is the messenger RNA that carries genetic information. So the best answer identifies the amino acids that must be obtained from the diet.