The covalent bond that holds amino acids together in a protein is called: Select one: a. hydrogen bond b. peptide bond c. polypeptide bond d. amino bond
The Correct Answer and Explanation is:
The correct answer is: b. peptide bond
A peptide bond is the covalent link formed between amino acids in proteins. This bond connects the carboxyl group of one amino acid to the amino group of another through a condensation reaction that releases a molecule of water. The result is a strong, stable bond fundamental to protein structure.
When multiple amino acids join via peptide bonds, they form a polypeptide chain. Each bond plays a critical role in maintaining the protein’s primary structure. This linear sequence of amino acids folds into secondary, tertiary, and sometimes quaternary structures, depending on the interactions among side chains and the surrounding environment. The specific folding of a polypeptide chain determines its biological function.
The formation of peptide bonds takes place in the ribosomes of the cell. During translation, the mRNA template is read and amino acids are linked in the correct order. Each time a new amino acid is added, a peptide bond forms between it and the existing chain. This stepwise construction continues until the entire protein is synthesized.
Peptide bonds are particularly stable under physiological conditions. This stability ensures that proteins maintain their structural integrity while carrying out essential functions such as catalysis, transport, and cellular signaling. Unlike hydrogen bonds, which are weaker and responsible for secondary structures like alpha-helices and beta-sheets, peptide bonds are not easily broken unless exposed to extreme chemical or enzymatic conditions.
In contrast to options like polypeptide bond or amino bond, which are more general or imprecise, the term peptide bond specifically refers to this covalent linkage. Understanding how peptide bonds form and function gives insight into everything from enzyme action to genetic expression. It is a cornerstone of biochemistry and molecular biology.
