Question

where does a peptide bond form?
between the five - carbon sugar of one nucleotide and the phosphate group of another nucleotide
between the r group of one amino acid and the carboxyl group of another amino acid
between the amino group of one amino acid and the carboxyl group of another amino acid
between the nitrogenous base of one nucleotide and the phosphate group of another nucleotide

Explanation:

A peptide bond is formed through a condensation reaction. In this reaction, the amino group ($\ce{-NH2}$) of one amino acid reacts with the carboxyl group ($\ce{-COOH}$) of another amino acid. A molecule of water ($\ce{H2O}$) is eliminated, and the resulting bond ($\ce{-CO - NH -}$) is the peptide bond.

• The first option describes a phosphodiester bond (in nucleic acids, between sugar and phosphate of nucleotides).
• The second option: The R - group is not involved in peptide bond formation.
• The fourth option: This is not a valid bond description for peptide bond formation (also related to nucleotide - like structures).

Answer:

between the amino group of one amino acid and the carboxyl group of another amino acid