BC E1PS1
10. A researcher has introduced a short interfering (si) RNA against DNA polymerase-Beta into cultured human cells. These cells are most likely to be defective in which one of the following pathways? A. DNA repair. B. DNA supercoiling. C. Extension of telomere sequences. D. Formation of Okazaki fragments. E. Synthesis of Alu repeats.
A
14. A Polymerase Chain Reaction does not include: A. A DNA helicase. B. A DNA sequence to be amplified. C. A heat-stable DNA polymerase. D. dATP. E. Oligonucleotide primer(s).
A
16. Which of the following statements about eukaryotic RNAs and RNA polymerases is true? A. Heterogeneous nuclear RNA (hnRNA) production involves RNA polymerase II. B. Processing of RNA is limited to those transcripts formed by RNA polymerase II. C. RNA polymerase II is insensitive to the mushroom toxin alpha-amanitin. D. RNA polymerase III is able to directly bind to its target promoter. E. RNA polymerase III is located primarily in the nucleolus.
A
17. Select the incorrect statement regarding the promoters utilized by RNA pol II: A. They contain DNA sequences that are resistant to cleavage by DNase I. B. They are located close to (~25 -35bp) the transcription start site. C. They generally contain the sequence TATA. D. They interact with basal transcription factors. E. They work in concert with enhancer elements.
A
23. The compound Gleevec (also termed STI571 or Imatinib) is useful for treating chronic myelogenous leukemia because it: A. Is an inhibitor of the kinase activity of the Bcr-Abl fusion protein. B. Is an inhibitor of the promoter associated with the Bcr-Abl fusion protein. C. Reactivates mutant p53. D. Reverses the translocation between chromosomes 9 and 22. E. Selectively inhibits splicing of c-abl pre-mRNA.
A
24. A clinic wishes to verify the concentration of a purified protein using spectroscopy. Which of the following contributes most to the absorption spectrum of the protein at 280 nm? A. aromatic amino acids such as tyrosine and tryptophan. B. disulfide bridges formed by cysteine. C. hydrogen bonding. D. the hydroxyl (OH-containing) amino acids. E. the peptide bonds.
A
29. The mutation that causes sickle cell disease is replacement of Glu at residue 6 in the chain. Individuals with sickle cell disease typically do not show symptoms at birth because A. the Beta chain is not predominant until after birth. B. bisphosphoglycerate is not present in the circulation until after birth. C. 120 days are required for red blood cell turnover after an oxygen deprivation event. D. the secondary event of malarial parasite infection has not yet occurred. E. aggregation of sickled hemoglobin (HbS) typically requires 90 or more days after birth.
A
CQuestions 2-4. Match the following classes of "junk DNA" with the most appropriate statement: A. Line elements B. Processed pseudogenes C. Alu repeats D. Simple sequence repeats (e.g. minisatellites) E. Telomeres 2. Some members encode a reverse transcriptase
A
Questions 19-20. Match the following factors required for protein translation with the most appropriate statement: A. Elongation factor 1 (EF1) B. Elongation factor 2 (EF2) C. Eukaryotic initiation factor 2 (eIF2) D. Eukaryotic initiation factor 4 (eIF4) E. Termination Factor 20. Required to properly dock amino-acyl-tRNAs into the A site.
A
Questions 6-8. Match the following proteins needed for DNA replication with the most appropriate statement. A. Polymerase delta B. Proliferating Cell Nuclear Antigen (PCNA). C. RPA (also termed Human single stranded binding protein). D. The Mcm complex. E. The polymerase /primase complex. 6. Has a 3' -> 5' exonuclease (or proofreading) activity.
A
18. Identify the incorrect statement regarding the regulation of transcription in eukaryotes: A. Acetylation of histones is associated with activation of transcription. B. Activation of transcription requires the selective removal of histone H2A. C. Inactive genes are present in heterochromatin. D. Many housekeeping genes contain promoters that are associated with CpG islands. E. Methylation of CpG sequences is associated with inactivation of transcription.
B
21. Identify the incorrect statement regarding eukaryotic ribosomes: A. The large (60S) ribosomal subunit assembles at the initiator AUG codon. B. They consist of two classes, one of which interacts with the endoplasmic reticulum. C. They contain peptidyl transferase. D. They contain RNA molecules synthesized by RNA polymerase I.
B
25. Select the correct order of events in collagen synthesis following translation of mRNA into protein 1. Hydroxylation 2. Formation of allysine 3. Cleavage of propeptides from procollagen 4. Triple helix formation A. 1,2,3,4 B. 1,4,3,2 C. 3,1,2,4 D. 4,1,3,2 E. 4,1,2,3
B
5. Identify the incorrect statement regarding histones or nucleosomes. A. Acetylation modulates the interaction between histones and DNA. B. DNA (~140-160 bp) is spooled within the inner surface of each nucleosome. C. Each nucleosome core particle contains two each of histones H2A, H2B, H3 and H4. D. Histone H1 is not part of the core particle. E. Nucleosomes are further ordered into chromatin fibers.
B
Questions 2-4. Match the following classes of "junk DNA" with the most appropriate statement: A. Line elements B. Processed pseudogenes C. Alu repeats D. Simple sequence repeats (e.g. minisatellites) E. Telomeres 3. DNA copies of cellular mRNA molecules
B
Questions 6-8. Match the following proteins needed for DNA replication with the most appropriate statement. A. Polymerase delta B. Proliferating Cell Nuclear Antigen (PCNA). C. RPA (also termed Human single stranded binding protein). D. The Mcm complex. E. The polymerase-alpha/primase complex. 7. Serves as a molecular clamp.
B
1. A sample of double-stranded DNA was analyzed and it was determined that the molar ratio of cytosine is 20%. Based on this information, what is the content of adenine? A. 10% B. 20% C. 30% D. 40% E. 60%
C
12. Prenatal diagnosis of hemoglobin S (sickle cell hemoglobin) by Southern blotting analysis requires all of the following except: A. A restriction endonuclease. B. A specific probe for beta-globin. C. An antibody against hemoglobin S. D. DNA from the fetus. E. Gel electrophoresis.
C
13. Given two populations of cells, DNA microarrays are most suitable for detecting changes in which of the following: A. Length of polymorphic satellite sequences. B. Length of telomere sequences. C. Levels of gene expression. D. Levels of protein synthesis. E. Levels of chromosomal translocations.
C
22. A change in nucleotide sequence that results in the introduction of a stop codon is termed a: A. Frame-shift mutation B. Missense mutation C. Nonsense mutation D. Silent mutation E. None of the above
C
28. Which of the following molecules preferentially destabilizes the taut (deoxy) form of hemoglobin? A. carbon dioxide B. bisphosphoglycerate C. oxygen D. calcium E. hydrogen ion (H+)
C
Questions 19-20. Match the following factors required for protein translation with the most appropriate statement: A. Elongation factor 1 (EF1) B. Elongation factor 2 (EF2) C. Eukaryotic initiation factor 2 (eIF2) D. Eukaryotic initiation factor 4 (eIF4) E. Termination Factor 19. Binds to the initiator Met-tRNA.
C
11. Identify the incorrect statement regarding mismatch repair in humans. A. Defects in this system are related to hereditary non-polyposis colon cancer. B. During the repair process, both the mismatched and surrounding bases are removed. C. The mismatched bases frequently arise from replication errors. D. The mismatched base is removed by a glycosidase that creates an AP site. E. The protein encoded by the human Mut S homologue (hMSH) binds to mismatched bases.
D
26. Collagen type III comprises three Alpha-1(III) chains. Why is a patient heterozygous for a mutation in a monomeric collagen processing enzyme less likely to present with a defect in collagen type III function than a patient who is heterozygous for a mutation in a structural gene of collagen? A. A single collagen processing enzyme is in molar excess over procollagen type III. B. Processing enzymes have a longer half-life in the cell than a collagen structural protein. C. Procollagen type III is in molar excess over a single collagen processing enzyme. D. The presence of a defective subunit in collagen causes the entire molecule to be defective. E. Up-regulation of other processing enzymes can compensate for a defect in any one particular processing enzyme.
D
Questions 6-8. Match the following proteins needed for DNA replication with the most appropriate statement. A. Polymerase delta B. Proliferating Cell Nuclear Antigen (PCNA). C. RPA (also termed Human single stranded binding protein). D. The Mcm complex. E. The polymerase /primase complex. 8. Thought to be the eukaryotic replicative helicase.
D
15. In humans, all of the following are transcription activators of RNA polymerase II except: A. Heat shock factor (HSF). B. MyoD. C. p53. D. Steroid hormone/receptor complexes. E. Transcription Factor III B (TFIII B).
E
27. Which of the following is most important in causing the chains of normal adult hemoglobin to form a tetramer? A. oxygenation B. beta-pleated sheet structure C. deoxygenation D. heme-heme interaction E. hydrophobic side-chains on the surface of each subunit
E
30. Acquired methemoglobinemia is attributable to A. a mutation of hemoglobin in the vicinity of the heme. B. decreased bisphosphoglycerate levels associated with high altitudes. C. increased activity of methemoglobin reductase. D. increased production of NADPH from the hexose monophosphate shunt. E. oxidizing compounds such as nitrates and nitrites.
E
9. Which of the following statements concerning DNA replication in eukaryotic cells is true? A. DNA synthesis takes place throughout the cell cycle. B. Eukaryotic origins of replication are highly homologous to prokaryotic origins. C. Leading-strand synthesis is catalyzed primarily by the polymerase -primase complex. D. Okazaki fragments are synthesized in a PCNA independent manner. E. RNA primer synthesis precedes DNA synthesis by DNA polymerases.
E
Questions 2-4. Match the following classes of "junk DNA" with the most appropriate statement: A. Line elements B. Processed pseudogenes C. Alu repeats D. Simple sequence repeats (e.g. minisatellites) E. Telomeres 4. Found at the ends of chromosomes
E
