Which of the following statements about peptide bonds are true?

Which of the following statements about peptide bonds are true?

  1. A tetrapeptide contains five amino acid residues.
  2. Peptide bonds form from nucleophilic attack by an electron pair on an alpha - amino nitrogen atom on an alpha - carboxyl carbon atom of another amino acid.
  3. Peptide bonds are ester linkages.
  4. Peptides are polymers of amino acids.
  5. Peptide bond formation is a hydrolysis reaction