Table of Contents
Peptide Bond Formation Between Two Amino Acids Biology Exam Guide
Peptide bonds covalently link two amino acids via dehydration synthesis to form proteins—not nucleotides, bases, or glucose—essential for polypeptide structure and function in General Biology certification prep.
Question
A peptide bond links:
A. Two nucleotides
B. Two Nitrogenous bases in DNA
C. Two molecules of glucose
D. Two amino acids
Answer
D. Two amino acids
Explanation
A peptide bond forms through a dehydration synthesis reaction between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another, releasing a water molecule and creating a covalent amide linkage (-CO-NH-) that joins their R-group side chains into polypeptide chains, the primary structure of proteins. This bond’s partial double-bond character from resonance imparts planarity and rigidity, restricting rotation and enabling alpha-helix and beta-sheet secondary structures stabilized by hydrogen bonds, while nucleotides link via phosphodiester bonds, nitrogenous bases pair via hydrogen bonds (not covalent), and glucose molecules form glycosidic bonds in carbohydrates. Peptide bonds are hydrolyzed by proteases during digestion or ubiquitination for degradation, underpinning protein synthesis from mRNA translation at ribosomes.