Formation of Peptides
              The linking of two or more amino acids by peptide bonds forms 
              a peptide.
              Peptides formed from
              • two amino acids are called dipeptides
              • three amino acids are called tripeptides
              • four amino acids are called tetrapeptides
             Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition                                     © 2015 Pearson Education, Inc. 
               Formation of Peptides
              A peptide bond
              • is an amide bond 
                                                                                       −
              • forms between the —COO  group of one amino acid and the 
                                                                          
                                      +
                    —NH  group of the next amino acid 
                                    3
             Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition                                     © 2015 Pearson Education, Inc. 
              Formation of a Dipeptide
                                   A peptide bond between glycine and alanine forms the dipeptide glycylalanine.
             Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition                                     © 2015 Pearson Education, Inc. 
               Study Check
              Draw the dipeptide Ser–Thr.
                       
             Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition                                     © 2015 Pearson Education, Inc. 
               Solution
              Draw the dipeptide Ser–Thr.
                                
             Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition                                     © 2015 Pearson Education, Inc.