Download Sample Questions for EXAM III

Sample questions for EXAM III. Please ignore question numbering; your exam will
consist of 40 multiple choice questions. These are questions lifted from previous
exams. Remember, course content varies from year to year and what is emphasized
in class changes from year to year. Use these questions as a guide only, but please
realize that your real exam will reflect what we did in class this year. Cancer
genetics will not be covered.
24.
The "abnormal" tautomeric form of guanine hydrogen bonds well with
1. the abnormal form of adenine.
2. the normal form of guanine.
3. the normal form of cytosine.
4. the normal form of thymine.
25. Intercalating agents
1. usually cause transitions.
2. usually cause chromosomal inversions.
3. may cause slippage during DNA replication, leading to insertions or
deletions.
4. should be tried for treason.
26.
A liver extract is often used in the Ames test
1. to inactivate a potential mutagen.
2. because some compounds are normally mutagenic to humans only after
being metabolized in the body.
3. as food for the rats used in the analysis.
4. because lobster extract is too expensive.
27. You finally graduated from college and you take a high-paying job as a genetic
councilor. An individual tells you that a rare disease is being passed along in her family
and that the age of onset of this disease unfortunately appears to be getting earlier and
earlier with each successive generation. You correctly tell this individual that the cause of
this disease is likely a
1. transversion.
2. centric fusion.
3. dynamic mutation.
4. recessive allele.
28.
What is the most common type of DNA damage caused by ultraviolet light?
1. DNA breaks.
2. thymine dimers.
3. alkylated bases.
4. apurinic sites.
29. Which statement is true?
1. nucleotide excision repair is defective in all cases of Xeroderma Pigmentosum.
2. it has been firmly established that photoreactivation is defective in certain
humans that are prone to cancer.
3. in humans, strand discrimination in mismatch repair has been shown to be
accomplished by methylation.
4. some cases of Xeroderma Pigmentosum involve a defect in a type of DNA
polymerase.
30.
Regarding the SOS response in bacteria:
1. it induces death.
2. if it is defective, it could contribute to the development of cancer.
3. it allows bacteria to survive damage by ultraviolet light but the cost is an
increased mutation rate.
4. it prevents mutations that might otherwise be induced by ultraviolet light.
31. Which statement about DNA repair is true?
1. photoreactivation can occur in the dark.
2. excision repair does not occur in humans.
3. defects in DNA repair may predispose an individual to cancer
4. DNA repair can correct a mutation after the mutation occurs.
1.
The first step in the transfer of protein-coding information present on one of the
two DNA strands is the production of a complementary RNA molecule. What is this
RNA molecule termed?
1. ribosomal RNA
2. operator RNA
3. messenger RNA
4. transfer RNA
2.
Both the codons UUU and UUC specify for the amino acid phenylalanine. What
is the term for this phenomenon?
1. degenerate
2. universal
3. unambiguous
4. non-overlapping
3.
What is the term for the triplet sequence in tRNA that is complementary to an
mRNA codon?
1. attenuator
2. anticodon
3. Shine-Dalgarno sequence
4. promoter
4.
How many different codons code for an amino acid?
1. 64
2. 20
3. 3
4. 61
5.
In eukaryotes, mRNA is transcribed by
1. RNA polymerase I
2. RNA polymerase II
3. RNA polymerase III
4. none of the above.
7.
The protein-synthesizing "machine" in prokaryotes and eukaryotes is called the
1. episome.
2. ribosome.
3. chromosome.
4. nucleolus.
14.
The lac operon
1. is present in mammals and bacteria.
2. is an example of inducible gene expression.
3. is normally expressed constitutively.
4. is an example of tissue-specific expression.
15.
What effect on transcription of the structural genes of the lac operon is observed
when lactose is present in the environment?
1. Transcription does not occur.
2. The genes are transcribed for only a single generation and then are shut off.
3. Lactose represses the synthesis of the repressor.
4. Transcription of the structural genes occurs when lactose is present.
16. When a bacterial cell is present in an environment where both lactose and glucose
are present, the glucose will be metabolized first and the lactose will be used when
the stores of glucose have been depleted. How does the bacterial cell recognize the
fact that glucose is present and turn off the transcription even when lactose is
present?
1. The lac promoter binds glucose and shuts down the lac operon.
2. Glucose is a repressor molecule.
3. Catabolite-activating protein-cAMP complex is required for transcription, and its
level is low when glucose is present.
4. The CAP binding site is activated.
17.
Consider a bacterial strain that has a mutant lac repressor that cannot bind the lac
operator region. If you were to introduce into this strain a stable F' element carrying a
mutant repressor gene, the cell would likely
1.synthesize lactose.
2. display inducible expression of the lac operon.
3. display constitutive expression of the lac operon.
4. probably not catabolize lactose.
18.
In attenuation of expression of the trp operon,
1. when tryptophan is scarce, the ribosome will stall and transcription will be terminated.
2. when tryptophan is scarce, the ribosome will not stall and transcription will not be
terminated.
3. when tryptophan is abundant, the ribosome will not stall and transcription will be
terminated.
4. when tryptophan is abundant, the ribosome will stall and transcription will be
terminated.
19.
The simplest of all transposable elements is called a(n)
1. Ac element.
2. P element.
3. insertion sequence.
4. transposon.
20.
Consider a hypothetical bacterial operon encoding genes needed for the
degradation of compound X. Which statement is most likely to be true?
1. when X is abundant, the operon is off.
2. when X is abundant, the operon is on.
3. this operon displays repressible, rather than inducible, expression.
4. the mRNA produced by this operon is monocistronic.
22.
The so-called "C-value paradox" says that
1. eukaryotes seem to have too little DNA.
2. prokaryotes seem to have too much DNA.
3. prokaryotes seem to have too little DNA.
4. there is a lot of DNA in eukaryotes that has no known function.
23. Enhancers can be found on either side of a gene, at some distance from a gene or
within the gene. They are termed cis regulators. What is the meaning of cis regulation?
1. genes that are adjacent to the cis-acting elements are regulated.
2. a diffusible protein product is made.
3. enhancers regulate genes on separate chromosomes.
4. intron splicing is altered
24. What is the function of eukaryotic transcription factors?
1. They recognize sequences within the enhancer and promoter regions and activate
transcription.
2. They direct the mRNA from the nucleus to the cytoplasm.
3. They initiate binding to the Shine-Dalgarno sequence.
4. They serve as sequences where the RNA polymerase binds
25.
The role of the cyclinB/CDK1 complex is
1. dephosphorylation of various proteins to allow the transition from G1 into S.
2. phosphorylation of various proteins to allow the transition from G2 into M.
3. arrest the cell at the G2/M transition until the proper signals are received.
4. dephosphorylation of various proteins to allow the transition from G2 into M.
26.
Which statement about cancer is true?
1. the development of cancer usually involves a single mutation.
2. "loss of heterozygosity" (LOH) is usually discussed in relation to tumor
suppressor genes.
3. oncogenes and proto-oncogenes are the same thing.
4. people with inherited predisposition to cancer are usually born homozygous for a
defective tumor suppressor gene.
27.
An individual develops retinal tumors in both eyes. This is most likely due to
1. Wilms tumor.
2. the nonfamilial form of retinoblastoma.
3. cancer in another part of the body that has metastasized to the eye.
4. the familial form of retinoblastoma
28.
Mutations in the p53 gene have been found in a wide range of human cancers.
This is most likely due to the fact that
1. p53 is important for control of the cell cycle in very specific cell types that can spread
when they become cancerous.
2. the p53 protein can move from cell to cell, causing cancer.
3. p53 is a kinase, which can phosphorylate many different cells cycle proteins.
4. p53 is involved in cell-cycle regulation in a wide variety of human cell types.
29.
Genomic instability
1. is often a hallmark of cancer.
2. might be increased by defects in DNA repair.
3. might be increased by defects in p53.
4. all of the above.
30.
A bacterial enzyme that cuts DNA within (or near) a short, specific sequence and
is used in many applications by molecular biologists is known as a
1.topoisomerase.
2.restriction enzyme.
3. polymerase.
4. glycosidase.