Standard 4f Preknowledge
4f) ***Students know why proteins having different amino acid sequences typically have different shapes and chemical properties.
CALIFORNIA FRAMEWORKS SUMMARY:
The 20 different protein-making amino acids have the same basic structure: an amino group; an acidic (carboxyl) group; and an R, or radical group. The protein is formed by the amino group of one amino acid linking to the carboxyl group of another amino acid. This bond, called the peptide bond, is repeated to form long molecular chains with the R groups attached along the polymer backbone.
The properties of these amino acids vary from one another because of both the order and the chemical properties of these R groups. Typically, the long protein molecule folds on itself, creating a three-dimensional structure related to its function. Structure, for example, may allow a protein to be a highly specific catalyst, or enzyme, able to position and hold other molecules. The R group of an amino acid consists of atoms that may include carbon, hydrogen, nitrogen, oxygen, and sulfur, depending on the amino acid. Amino acids containing sulfur sometimes play an important role of cross-linking and stabilizing polymer chains. Because of their various R groups, different amino acids vary in their chemical and physical properties, such as solubility in water, electrical charge, and size. These differences are reflected in the unique structure and function of each type of protein.