Download General Biochemistry Exam – 2002 Excess Acetyl

General Biochemistry Exam – 2002
1. Excess Acetyl-CoA causes:
a. Increased rate of gluconeogeneisis with high amounts of ATP
b. Increased rate of gluconeogeneisis with low amounts of ATP
c. Increased rate of pyruvate dehydrogenase
d. Decreased rate of pyruvate dehydrogenase
2. A mutation in the PK enzyme that results in the enzyme being nonfunctional
causes:
a. A decrease in 2,3 BPG
b. An increase in 2,3 BPG
c. No effect
d. The result is dependent upon the activity of HK
3. In aerobic glycolysis, there is no accumulation of pyruvate in liver cells because:
a. Lactate dehydrogenase is very active
b. The pyruvate becomes Acetyl-CoA
c. The ratio of NAD/NADH is very high
d. The pyruvate oxygenates NADH, which is produced by GA3P
dehydrogenase
4. For the production of purines, you must have:
a. B12
b. CO2, O2
c. Amino acids + Fatty acids
d. None of the above
5. To produce αKG from pyruvate, you need:
a. NADPH
b. CO2, O2, CoA
c. Lactate
d. Glycogen
6. The breakdown of tryglycerides is NOT related to:
a. cAMP
b. Glucagon
c. Adenylate cyclase
d. ATP
e. Epinephrine
f. HMG CoA
7. How many molecules of ATP are produced from the oxidation of C-18:1 :
a. 118.5
b. 117.
c. 122
d. 120
e. 106
8. If the breakdown and synthesis of fatty acids would occur simultaneously, the
pool of ATP molecules would:
a. Gain 14 ATP
b. Loose 14 ATP
c. Gain 18 ATP
d. Loose 24 ATP
e. Gain 12 ATP
9. A new drug was developed that slows the breakdown of transformylase, whose
function is to produce formyl-methionine tRNA. What would happen?
a. A halt in the production of new amino acids
b. The proteins synthesized are shorter
c. A loss of proteins during the synthesis
d. A charged and uncharged protein get caught in the tRNA
e. All of the above
f. None of the above
10. A problem with the enzyme galactose uridine transferase would cause:
a. High urinary glucose
b. High blood glucose
c. None of the above
11. What happens in the process of: ADP + Pi  ATP
a. ∆G increases
b. ∆G decreases
c. ∆G stays the same
d. It depends on the concentration of the materials
12. What do TA and TR have in common?
a. Both require cofactor TDP
b. Both have a transfer of two molecules
c. Both transform aldose to ketose
d. Both transform ketose to aldose
13. If two polar amino acids are replaced with two non-polar amino acids, what
happens?
a. Nothing happens
b. The level of polarity will decrease
c. The protein will become more hydrophobic
d. The protein will become more hydrophilic
14. What does the enzyme RNA polymerase in E. Coli require for reproduction?
a. DNA helicase
b. Primase
c. An AUG codon instead of +1 in DNA
d. Shine Delgarno in the 5’ UTR
e. dGTP, dATP, dUTP, dCTP
f. None of the above
15. Linoleic acid C-18:2 :
a. Is produced by animals
b. Is not produced by animals
c. Is produced by plants
16. The precursor of C-18:3 acid is:
a. Linolenic
b. Linoleic
c. Palmitic
17. If cyanide is added to the mitochondria, what will happen?
a. There will be an increase in O2 consumption
b. There will be a decrease in O2 consumption
c. ATP production will decrease
18. Two proteins were separated, one weighed 35,000 daltons and PI=11.6, and the
second weighed 35,200 and PI=26. Both proteins have GTPase activity. The best
method to separate the two proteins is:
a. Affinity chromatography with GTP
b. Isoelectric precipitation
c. Isoelectric focusing
d. Polyacrilamide gel
e. B+C
f. A+D
19. What is incorrect regarding the electron transfer chain?
a. An electric current on both sides of the internal membrane
b. The I-V complex are encoded by nuclear DNA and mitochondrial DNA
20. The addition of FDUMP does NOT increase the effectiveness of treatment with
methotrexate, explain:
a. FDUMP competes with the binding of thymidylate synthase that delays
the conversion of FdUMP-> dTMP. DTMP competes with methotrexate,
thus decreasing the effectiveness of the drug.
b. Both drugs compete with the reduction of dihydrofolate
c. FdUMP connects to thymidylate synthase. In the presence of
methotrexate there is no reduction of folate because the thymidylate
synthase is inactive. A delay by FDUMP is not effective.
d. The presence of methotrexate increases the ability of FdUMP to compete
with its analog; therefore its activity is not noticeable.
21. Anabolic metabolism of fructose in the liver:
a. Produces more ATP than the metabolism of glucose
b. Produces less ATP than the metabolism of glucose
c. Competes for affectivity at the level of hexokinase
d. Is controlled by phosphor-fructo-kinase
e. None of the above
22. A restriction enzyme recognizes and slices 5’CCCGGG 3’ without ethanol.
3’ GGGCCC5’
When 15% ethanol is added, then enzyme recognizes 5’GCCGGC3’
3’ CGGCCG5’
in addition to the previous sequence. The same thing occurs when the
reaction is done at 47 C.
a. Ethanol changes the shape of the protein, thus the activity changes
b. Ethanol’s effect causes a change in the active site of the enzyme
c. Ethanol changes the specificity of the enzyme, and it is less punctual
d. Ethanol changes the primary structure of the enzyme
e. A+B+C
f. A+B+C+D
23. What is incorrect?
a. NADH is created by the breakdown of fatty acids
b. NADH is created by the synthesis of fatty acids
c. NADPH is produced by the pentose phosphate pathway
d. NADPH is found in the cytosol
e. NADPH is produced by the malic enzyme pathway
24. A group of cells with acetate labeled with ATP were incubated but without
oxygen. In following the synthesis of cholesterol, the following was found:
a. Cholesterol
b. ‫סקוול‬
c. Lenestrol
d. Zimostrol
e. Bile acids
25. Glycolysis in the muscle requires:
a. CoA
b. NADPH
c. NAD
d. IMP
26. Red blood cells are damaged under oxidative stress because:
a. Because they have no mitochondria, they have no pentose phosphate
pathway
b. Because they have no nucleus, they have no pentose phosphate pathway
c. Because they have no mitochondria, they have no malic enzyme pathway
d. They have no glutathione
e. They have no catalase enzyme
27. The enzyme HMG CoA reductase is activated (directly and indirectly) by:
a. Loss of a phosphate group
b. Addition of a phosphate group
c. Insulin
d. cAMP
e. A or C
28. GRAPH Q
29. A researcher is holding a test tube with 1mg of a double-stranded plasmid
composed of 4000 base pairs (bp). The researcher boiled the plasmid and
separated the strands into two separate test tubes. Mark the correct response:
a. Each test tube has 0.5mg of plasmid
b. The sequence of nucleotides in one test tube completes the sequence of
nucleotides in the second test tube
c. Each test tube contains a circular strand of DNA with 400 nucleotides
d. The concentration of T nucleotides in test tube one is equal to the
concentration of A nucleotides in test tube 2.
e. The concentration of G nucleotides in test tube one is equal to the
concentration of C nucleotides in test tube 2.
f. B, C, and D are correct
g. A-E are correct
30. On a tRNA molecule, the elongated strand has the following sequence
(“N”) CGAT3’
(“M”)5’GCAT
Adenine on the “N” strand is replaced with thymine. DNA polymerase
incorrectly repaired the “M” strand leading to an A-T in the opposite order
(double mutation). What is correct:
a. The composition of the tRNA will NOT change
b. The ration of A:T in the tRNA will NOT change
c. ???
d. There will be no change in the area not undergoing translation in the
tRNA
31. A mutation occurs in the W gene of a mouse species. In the normal species and
the mutated species the amount of primary transcription is the same, but the
amount of secondary transcription in the cytoplasm is very low in the mutated
species as compared to the normal species. What is correct:
a. The mutation harmed the Shine-delgarno sequence in the W gene
b. The mutation harmed the polyadenylyl site in the 5’ end of the W gene
c. The mutation harmed the guanosine capping site at the 3’ end of the W
gene
d. B + D
e. None of the above
32. What enzymes are involved in the replication and repair of DNA?
a. DNA ligase
b. DNA helicase
c. DNA polymerase
d. DNA primase
e. A + B
f. B + C
33. Researchers were able to reconstruct x-ATPase in humans and in frogs. It was
discovered that all the amino acids were identical except for serin 2 (S) that were
found in humans and threonine (T) that were found in the frogs. When S was
replaced with T in humans, the enzyme improved its ability, and when T was
replaced with S in the frog, its affinity decreased. On the other hand, when a
mutation occurred and S or T was replaced with valine (V) the enzyme lost
catalytic activity. Mark the correct answer:
a. The S and the T are found in the active site of the enzyme
b. The amino acid T has a higher affinity for substrate as opposed to S or V
c. The protein will change is spatial structure due to the replacement with V
d. All the above are likely
34. Cancer patients received treatment with a drug that suppresses the activity of
HAT (histone acetyltransferase). Doctors extracted mRNA from the cancer cells
before and after the administration of treatment. After the treatment, the doctors
found that the amount of transcription had increased in some and decreased in
others. There was an improvement in the cancer situation with the treatment. A
possible explanation is:
a. HAT works to increase gene expression, therefore the patients has a
suppression of gene expression after treatment
b. HAT works to decrease gene expression, therefore gene expression among
the patients was turned on after treatment
c. The HAT suppressed the expression of repressor proteins, therefore there
was a decrease in the expression of some of the genes after the treatment
d. HAT works to express repressor proteins, therefore there was an increase
in the expression of some of the genes after the treatment
e. A + D
f. B + C