2.7.6 Protein Structure: A Summary

Question 1

confirmation

Answer 1

• of a protein is determined by the sequence of amino acids within the polypeptide chains

Question 2

four levels of protein structure

Answer 2

• primary, secondary, tertiary, and quaternary

structure

Question 3

primary

Answer 3

• The sequence of amino acids within a polypeptide is its primary structure.
• RNA directs the sequence of amino acids in a polypeptide.

Question 4

secondary

Answer 4

• Secondary structure is the regularly occurring shape of the polypeptide that results from hydrogen bonding between amino acids within the polypeptide chain. Examples of secondary structure include the alpha helix
  and beta pleated sheet.

Question 5

tertiary

Answer 5

• Tertiary structure is the three-dimensional shape that a protein takes due to interactions between R groups. Several types of interactions exist between R groups. R groups that are hydrophobic tend to fold into the center of the polypeptide because water repels them. As the groups pack together, Van der Waals interactions occur between them. Ionic bonds can form between R groups of opposite charges. Disulfide bridges, strong covalent bonds, form between two sulfhydril groups of cysteine.

Question 6

quaternary

Answer 6

• Quaternary structure is the final level of protein structure. It involves the interaction of multiple polypeptides to form the final protein. An example is hemoglobin, which is made of four polypeptide chains.

Question 7

The simplest type of mutation that can occur in a protein is due to a point mutation that results in one amino-acid residue being replaced by another. This single change could result in

Answer 7

• a different primary structure, a different tertiary structure, a complete loss of functionality

Question 8

Proteins differ from one another because

Answer 8

• the exact sequence of amino acids is unique to each protein

Question 9

Which levels of protein structure would be affected by the disruption of hydrogen bonding?

Answer 9

• secondary, tertiary, quaternary

Question 10

All proteins are

Answer 10

• polymers of amino acids

Question 11

Protein shape is the same as protein conformation, and protein conformation dictates

Answer 11

• protein function

Question 12

In proteins, tertiary structure is most influenced by

Answer 12

• R groups