Which of these choices INCORRECTLY pairs the level of protein structure with the definition of that level of structure?

A) Primary structure- sequence of amino acids

B) Tertiary structure- 4D folding due to interactions of distant amino acids and between amino acids and the environment

C) Quaternary- arrangement of multiple polypeptides

D) Secondary- interactions between adjacent amino acids

B

Which protein structure is common in alpha-keratin of hair and fingernails?

A) Primary structure

B) Secondary structure

C) Tertiary structure

D) Quaternary structure

B

Which of the following is an example of the secondary structure of a protein?

A) Disulfide bonds between cysteine residues

B) Peptide bonding between amino acids

C) Hydrogen bonding between an amine and carbonyl group

D) Hydrophobic interactions

E) Hydrogen bonding between R groups

C

Which of these statements concerning peptide bonds is FALSE?

A) Their formation involves a reaction between an amino group and a carboxyl.

B) They are the primary bonds that hold amino acids together.

C) They have a partial double bond character.

D) Their formation involves hydration reactions.

D

A new drug is developed which selectively cleaves covalent bonds between two sulfur atoms of non-adjacent amino acids in a polypeptide chain. Which level of protein structure in affected molecules would be most directly affected by the drug?

A) Primary structure

B) Quaternary structure

C) Tertiary structure

D) Secondary structure

C

Which of the following statements is NOT true regarding the comparison of the alpha-helix structure to the beta-sheet structure in proteins?

A) All possible bonds between the peptide carbonyl oxygen (C=O) and the amide hydrogen (N-H) are formed in each.

B) Each is an example of secondary structure.

C) Each is stabilized by inter-chain hydrogen bonds.

D) Each may occur in typical globular proteins.

C

Proteins can have a maximum of four levels of structure: primary, secondary, tertiary, and quaternary. Although the proteins can spontaneously fold to a functional conformation, there are a variety of denaturing agents that can be used to disrupt the folding strategies of proteins. Mercaptoethanol is an example of a protein denaturing agent; its mechanism for dismantling proteins is to disrupt the disulfide bonds found in the protein. Which of the following levels of structure in a protein would not be disrupted by the introduction of mercaptoethanol?

A) All of the given levels will be affected

B) Quaternary structure

C) Secondary structure

D) Tertiary structure

C

Proteins can have a maximum of four levels of structure: primary, secondary, tertiary, and quaternary. Although the proteins can spontaneously fold to a functional conformation, there are a variety of denaturing agents that can be used to disrupt the folding strategies of proteins. When urea is introduced to a protein, the hydrogen bonds holding the protein together are disrupted. Which of the following levels of structure would not be affected by urea?

A) Tertiary structure

B) Secondary structure

C) Quaternary structure

D) All given levels would be affected

D

Collagen, the most abundant protein in the body, is an example of what type of protein?

A) Integral

B) Structural

C) Peripheral

D) globular

B

You are given the amino acid sequence Ala-Gly-His-Tyr. This is an example of which level of protein structure?

A) Quaternary

B) Primary

C) Tertiary

D) Secondary

E) None of the above answers are correct

B