Question

amino acids are the building blocks of proteins. select the true statements. human body cells make essential amino acids from sugar molecules. each amino acid has an amino group, a carboxyl group, and an r - group. a peptide bond forms between two amino acids. many amino acids linked together form a polypeptide.

Explanation:

• Essential amino acids cannot be made by the human body and must be obtained from the diet. So the statement "Human body cells make essential amino acids from sugar molecules" is false.
• The general structure of an amino acid includes an amino group ($-NH_2$), a carboxyl group ($-COOH$), and an R - group (which varies among different amino acids). So the statement "Each amino acid has an amino group, a carboxyl group, and an R - group" is true.
• A peptide bond is formed between the amino group of one amino acid and the carboxyl group of another amino acid. So the statement "A peptide bond forms between two amino acids" is true.
• When many amino acids are linked together by peptide bonds, they form a polypeptide. So the statement "Many amino acids linked together form a polypeptide" is true.

Answer:

• B. Each amino acid has an amino group, a carboxyl group, and an R - group.
• C. A peptide bond forms between two amino acids.
• D. Many amino acids linked together form a polypeptide.