Final answer:
A peptide bond is an amide bond between two amino acids, whereby each bond corresponds to a pair of amino acids. In a peptide chain, the number of peptide bonds is always one less than the number of amino acids present.
Step-by-step explanation:
A peptide bond is the amide bond that links two amino acids together in a protein. When two amino acids form a dipeptide through a dehydration reaction, one molecule of water is released, and one peptide bond is created. Therefore, for each peptide bond, there must be two amino acids involved. This means in a chain of amino acids forming a peptide, the number of peptide bonds is always one less than the number of amino acids in the chain. For example, a dipeptide, which has two amino acids, would have one peptide bond, a tripeptide with three amino acids would have two peptide bonds, and so forth.
As the chain lengthens with the addition of more amino acids, new peptide bonds are formed, each time joining another amino acid to the chain and extending the peptide or protein. The sequence and quantity of these amino acids are fundamental in determining the final shape, size, and function of the resultant protein or polypeptide.