Question

1. the first five amino acids in this polypeptide are serine, tyrosine, alanine, phenylalanine, and valine, in that order (ser - tyr - ala - phe - val). if the amino acids were changed or rearranged (i.e. to val - phe - ala - ser - tyr), the polypeptide would have a different name and identity. with your group, use this information to write a definition of the primary structure of a protein.
2. locate the secondary protein structure in model 2.

a. what types of bonds are holding the secondary structure in place?
b. what groups on the amino acids are always involved in these bonds?

1. draw a rectangle around two different r - groups on the amino acids in the secondary structure in model 2.
2. is there any interaction between r - groups in the secondary structure in model 2?
3. secondary protein structure can take the form of an alpha(α)-helix or a beta(β)-pleated sheet, as illustrated below.

a. which drawing represents an α - helix, molecule 1 or molecule 2? explain your reasoning.
b. which drawing represents a β - pleated sheet? explain your reasoning.

1. with your group, write a grammatically correct sentence that summarizes how the secondary protein structure is formed from the primary structure.

Explanation:

11a. Hydrogen bonds hold the secondary protein - structure in place as they form between the backbone atoms of amino - acids in the polypeptide chain.
11b. The amino and carboxyl groups on the amino - acids are involved in forming hydrogen bonds that stabilize the secondary structure.

1. In the secondary structure, there is no direct interaction between R - groups. Secondary structure is mainly determined by backbone - backbone interactions (hydrogen bonds between amino and carboxyl groups of different amino - acids).

14a. Molecule 2 represents an α - helix because it has a coiled structure with hydrogen bonds between the backbone atoms that run parallel to the axis of the helix.
14b. Molecule 1 represents a β - pleated sheet as it has a flat, sheet - like structure with hydrogen bonds between adjacent polypeptide chains.

1. The secondary protein structure is formed when the primary sequence of amino - acids in a polypeptide chain undergoes hydrogen bonding between the amino and carboxyl groups of the backbone, resulting in structures like α - helices and β - pleated sheets.

Answer:

11a. Hydrogen bonds
11b. Amino and carboxyl groups

1. No

14a. Molecule 2, because it has a coiled structure with backbone - backbone hydrogen bonds parallel to the helix axis.
14b. Molecule 1, because it has a flat structure with hydrogen bonds between adjacent chains.

1. The secondary protein structure is formed when the primary amino - acid sequence undergoes backbone - backbone hydrogen bonding to create α - helices and β - pleated sheets.