biochemistry
Chapter 2- proteins
1. Noncovalent bonds include all the following except:
A.peptide bond
B.ionic bond
C.hydrogen bond
D.van der waals interaction
E.hydrophobic interaction
2. What feature of a protein can be used to predict its function directly ?
A.number of amino acids
B.overall charge of the molecule
C.molecular weight
D.secondary structure
E.conformation
3. Which one of the following statements about protein structure is correct?
A.the α-helix is stabilized primary by ionic interactions between the side chains of amino acids.
B.the formation of a disulfide bond in a protein requires that the two participating cysteine residues be adjacent to each other in the primary sequence of the protein.
C.the stability of quarternary structure in proteins is mainly due to covalent bonds among the subunits.
D.the information for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain.
E.denaturation often results in hydrolysis of peptide bonds of the protein
4. The peptide bond
A.is a special type of noncovalent bonds
B.has a partial double bond character.
C.is ionized at ph 7.
D.is cleaved by organic solvents that denature proteins.
5. What is primary structure of proteins?
A.The sequence of amino acids in a protein
B.The amount of amino acids in a protein
C.The number of amino acids in a protein
D.The number of peptide bonds in a protein
E.The number of disulfide bonds in a protein
6. Which of the structure is not part of proteins?
A. Right-hand double helix
B.α-helix
C.β-sheet
D.β-bends
E. Non-repetitive secondary structure
7. Which of the interactions between the amino acid side chains guide the folding of the polypeptide to form tertiary structure of globular proteins?
A.Disulfide bonds
B.Hydrophobic interactions
C.Hydrogen bonds
D.ionic interactions
E. Phosphodiester linkage
8. What is quaternary structure of proteins? Choose the ONE correct answer:
A. Subunits are held together by noncovalent interaction
B. Subunits may not function independently of each other
C. Subunits may not cooperative
D. Subunits are held together by hydrogen bonds only
E. Subunits are held together by ionic bonds only
9. Which of the description about protein is wrong?
A.Proteins are linear polymers built of monomer units called amino acids
B.Proteins can interact with one another and with other biological macromolecules to form complex assemblies
C.Proteins contain a wide range of functional groups
D.Some proteins are quite rigid, whereas others display limited flexibility
E.Both D and L amino acids are constituents of proteins
10. Which one of the following statements is correct?
A.Protein denaturation results in change in primary structure
B.Protein denaturation results in change in secondary and tertiary structure, not in primary structure
C.Protein denaturation is irreversible
D.The information needed for correct protein folding is contained in the secondary structure
E.Protein denaturing agents include heat, organic solvents, mechanical mixing, not strong acids or bases