Question

proteins are made up of ______ held together by ______ bonds.

multiple choice

amino acids, ionic

monosaccharides, ionic

amino acids, peptide

monosaccharides, peptide

Explanation:

To solve this, we recall the structure of proteins. Proteins are polymers of amino acids. The bond that links amino acids together in a protein is a peptide bond (formed between the carboxyl group of one amino acid and the amino group of another, with the loss of a water molecule). Monosaccharides are the building blocks of carbohydrates, not proteins, so options with monosaccharides are incorrect. Ionic bonds are not the primary bonds holding amino acids in proteins; peptide bonds are. So the correct pair is amino acids held by peptide bonds.

Answer:

C. amino acids, peptide (assuming the third option is labeled C; if the original labels were different, adjust the identifier but keep the text "amino acids, peptide")