Chapter 3 The Same 20 Amino Acids Serve as Building blocks for All Proteins in Nature Homework 2 part 1: Ch 5 problems 2, 9, 12, 16.Chapter 3 The Same 20 Amino Acids Serve as Building Blocks for All Proteins in Nature Homework 2 part 1: Ch. 5 problems 2, 9, 12, 16