Biochemistry Exam 1
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Biochemistry Exam 1
- 1.A weak acid can act as a buffer......
- A.
At pH values=pK±0.1
- B.
At pH values = pK ± 1
- C.
At pH values = pK ± 2
- D.
Only at body temperatures
- E.
None of the above
- 2.Which of the following is considered to be a fibrous protein?
- A.
Hemoglobin
- B.
Immunoglobulin
- C.
Keratin
- D.
Myoglobin
- E.
None of the above
- 3.Disulfide bonds most often stabilize the native structure of:
- A.
Dimeric proteins
- B.
Extracellular proteins
- C.
Hydrophobic proteins
- D.
Intracellular proteins
- E.
All of the above
- 4.In sickle cell anemia, the basis of the malfunction of the hemoglobin molecule is:
- A.
Faulty binding of the heme groups
- B.
Incorrect secondary structure
- C.
Reduced affinity for oxygen
- D.
Substitution of a single amino acid
- E.
None of the above
- 5.When BPG (2,3-Bisphosphoglycerate) binds to ______ site(s) on hemoglobin ________ its affinity for O2
- A.
Four/decreases
- B.
Four/increases
- C.
One/decreases
- D.
One/increases
- E.
None of the above
- 6.The complementarity-determining regions (CDRs)
- A.
Are found at the antigen-binding sites
- B.
Reside in the VL and VH regions of the IgG molecule
- C.
Reside in the CL and CH regions of the IgG molecule
- D.
A and B are correct
- E.
A and C are correct
- 7.Antibodies of the IgG class
- A.
Consist of four subunits
- B.
Are glycoproteins
- C.
Have inter- and intra-chain disulfide crosslinks
- D.
All three choices are correct
- E.
None of the choices are correct
- 8.The two exonuclease activities of DNA polymerase I
- A.
Are coupled during the formation of "gapped DNA"
- B.
Degrade DNA in a 3' --> 5' direction
- C.
Degrade DNA in a 5' --> 3' direction
- D.
Occur at two different active sites
- E.
None of the above
- 9.The RNA primers used to initiate replication in E. coli
- A.
Are joined together by DNA ligase
- B.
Are removed by helicase + ATP
- C.
Are removed by Pol I "nick translation
- D.
Result in Okazaki fragments on the leading strand
- E.
None of the above
- 10.On the ribosome, mRNA binds ____; the peptidyl transferase reaction occurs ____
- A.
Between the subunits; on the large subunit
- B.
Between the subunits; on the small subunit
- C.
To the large subunit; on the small subunit
- D.
To the small subunit; on the large subunit
- E.
None of the above
- 11.The pKa of an ionizable side chain, such as imidazole in histidine, can be determined with NMR because
- A.
Protonated imidazole has twice the number of protons
- B.
The chemical shift of His differs from that of His+
- C.
The pKa is near neutrality
- D.
Unprotonated imidazole is invisible in the spectrum
- E.
None of the above
- 12.During the synthesis of a 100 residue protein, the number of GTP molecules used during initiation, elongation, and termination are, respectively:
- A.
1, 100, 1
- B.
1, 198, 1
- C.
1, 200, 1
- D.
2, 198, 2
- E.
None of the above
- 13.Peripheral membrane proteins
- A.
Are not accommodated by the fluid mosaic model
- B.
Are only of peripheral interest to membrane biologists
- C.
Can be dissociated from membranes relatively easily, e.g., high salt treatment
- D.
Can undergo transverse membrane motion, i.e. "flip-flop"
- E.
None of the above
- 14.During glycolysis the following reaction requires NAD+:
- A.
Alcohol dehydrogenase
- B.
Glyceraldehyde-3-phosphate dehydrogenase
- C.
Lactate dehydrogenase
- D.
Pyruvate dehydrogenase
- E.
All of the above
- 15.Since the energy released by all the reactions of glycolysis is 185 kJ/mol glucose, and ____ mol ATP is/are produced per mol glucose, the overall efficiency of glycolysis is about ____
- A.
1/ 16%
- B.
1 /33%
- C.
2 /33%
- D.
2 /50%
- E.
None of the above
- 16.Glycogen digestion in the gut begins with a ________ reaction; intracellular glycogen breakdown begins with a ________ reaction.
- A.
Hydrolysis; hydrolysis
- B.
Hydrolysis; phosphorolysis
- C.
Hydrolysis; phosphorylation
- D.
Phosphorolysis; hydrolysis
- E.
None of the above
- 17.The correct order, from fastest-acting to slowest, for the time scale of these regulatory mechanisms is:
- A.
Allosteric - covalent - genetic
- B.
Allosteric - genetic - covalent
- C.
Covalent - genetic - allosteric
- D.
Genetic - allosteric - covalent
- E.
None of the above
- 18.Mitochondrial ATP synthesis requires
- A.
A [H+] gradient
- B.
A membrane potential
- C.
An intact inner mitochondrial membrane
- D.
All of the above
- E.
None of the above
- 19.Which of the following enzymes does not catalyze a physiologically irreversible step in glycolysis?
- A.
Hexokinase
- B.
Phosphofructokinase
- C.
Phosphoglycerate kinase
- D.
Pyruvate kinase
- E.
None of the above
- 20.Following the addition of a mitochondrial respiratory inhibitor, components of the electron transport chain
- A.
All components will be oxidized
- B.
Downstream of the blockage will be reduced
- C.
Upstream of the blockage will be oxidized
- D.
Upstream of the blockage will be reduced
- E.
None of the above
- 21.For the following reaction: [FAD] + 2 Cyt c (Fe2+) + 2H+ -> [FADH2] + 2 Cyt c (Fe3+) the electron donor is _______; the reduced product is ________
- A.
2 Cyt c (Fe2+); [FADH2]
- B.
[FAD]; [FADH2]
- C.
2 Cyt c (Fe2+); 2 Cyt c (Fe3+)
- D.
[FAD]; 2 Cyt c (Fe3+)
- E.
None of the above
- 22.Acetyl groups (e.g. for lipid biosynthesis) are transported out of the mitochondria indirectly using
- A.
Acetyl carnitine
- B.
Acetyl phosphate
- C.
Citrate
- D.
Malate
- E.
All of the above
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