Chapter 5 Section 2: Amino Acid Structures, after p. 190:
Topic Name: Carnegie Mellon University "Side-by-Side Amino Acid Viewer"
Look at the structures of a few of the amino acids that are linked together to make polypeptides and proteins. Read the information in the LEFT FRAME to understand how the site works. In the RIGHT FRAME, follow the X boxes to learn about the features that amino acids have in common:
A central carbon atom or alpha carbon (in BLACK)
A carboxyl group (in RED)
An amino group (in BLUE)
A side group (in GREY).
Glycine, the smallest amino acid, is the only amino acid that lacks a side group. It is the side group that gives each amino acid its unique structure and properties. Some side groups are small, some are large, some are hydrophilic (water-loving), and some are hydrophobic (water-fearing). The sequence of these amino acids and their side groups determines the 3-dimensional structure that the protein will adopt.
Now in the left frame select the amino acid ALANINE (you may have to select another amino acid and then go back and select alanine to get the alanine frame to load). In the right frame select PHENYLALANINE.
Describe how these two amino acids differ.
Now select LYSINE in the right frame. How does lysine differ from either alanine or phenylalanine?
Amino acids are joined together to form peptides and proteins. In one frame select DIPEPTIDE, and in the other select TETRAPEPTIDE. Compare these structures. Now select OCTAPEPTIDE in one frame.
What is happening as more amino acids are added? Do you see a 3-D structure beginning to form?