5 Written questions
5 Matching questions
- Why might a laboratory be using dideoxy nucleotides?
A) to visualize DNA expression
B) to separate DNA fragments
C) to clone the breakpoints of cut DNA
D) to sequence a DNA fragment
E) to produce cDNA from mRNA
- Some viruses can be crystallized and their structures analyzed. One such virus isDesmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets.
If this virus has capsomeres with 20 facets, how many proteins form each one?
- Tumor-suppressor genes
A) are frequently overexpressed in cancerous cells.
B) do all of the above.
C) can encode proteins that promote DNA repair or cell-cell adhesion.
D) often encode proteins that stimulate the cell cycle.
E) are cancer-causing genes introduced into cells by viruses.
- In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase.
Virus Nuclease A ( Sensitivity Dnase) (Genome as mRNA -) (Polymerase -)
Virus Nuclease B (Sensitivity Rnase) (Genome as mRNA +) (Polymerase -)
Virus Nuclease C (Sensitivity Dnase) (Genome as mRNA -) (Polymerase +)
Virus Nuclease D (Sensitivity Rnase) (Genome as mRNA -) (Polymerase +)
Virus Nuclease E (Sensitivity Rnase) (Genome as mRNA +) (Polymerase -)
Based on the above table, which virus meets the Baltimore requirements for a retrovirus?
- As genetic technology makes testing for a wide variety of genotypes possible, which of the following is likely to be an increasingly troublesome issue?
A) discrimination against certain racial groups because of major genetic differences
B) the need to legislate for the protection of the privacy of genetic information
C) using technology to identify genes that cause criminal behaviors D) alteration of human phenotypes to prevent early disease
E) use of genotype information to provide positive identification of criminals
- a D) D
- b D) to sequence a DNA fragment
- c B) ~6
- d B) the need to legislate for the protection of the privacy of genetic information
- e C) can encode proteins that promote DNA repair or cell-cell adhesion
5 Multiple choice questions
- C) The viral envelope mediates entry into the cell, the capsid entry into the nuclear membrane, and the genome is all that enters the nucleus.
- D) The BAC carries more DNA, the BAC can carry entire genes and their regulatory elements, and larger BACs are easier to store.
- D) continuous transcription of the operon's genes
- E) retroviruses
- C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow
5 True/False questions
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious
II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope
III. culturing the substance by itself on nutritive medium, away from any plant cells
IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious
Which treatment could definitively determine whether or not the component is a viroid?
E) first II and then III → A) I
Viral envelopes can best be analyzed with which of the following techniques?
A) transmission electron microscopy
B) staining and visualization with the light microscope
C) immunofluorescent tagging of capsid proteins
D) antibodies against specific proteins not found in the host membranes
E) use of plaque assays for quantitative measurement of viral titer → B) RNA polymerase must bind to the promoter, and the repressor must be inactive
What is the function of reverse transcriptase in retroviruses?
A) It translates viral RNA into proteins.
B) It uses viral RNA as a template for making complementary RNA strands.
C) It uses viral RNA as a template for DNA synthesis.
D) It hydrolyzes the host cell's DNA. E) It converts host cell RNA into viral DNA. → C) it uses viral RNA as a template for DNA synthesis
A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
A) irreversible binding of the repressor to the operator.
B) continuous transcription of the structural gene controlled by that regulator.
C) inactivation of RNA polymerase by alteration of its active site.
D) complete inhibition of transcription of the structural gene controlled by that regulator.
E) continuous translation of the mRNA because of alteration of its structure. → B) continuous transcripton of the structural gene controlled by that regulator
Plants are more readily manipulated by genetic engineering than are animals because
A) plant genes do not contain introns.
B) genes can be inserted into plant cells by microinjection.
C) a somatic plant cell can often give rise to a complete plant.
D) more vectors are available for transferring recombinant DNA into plant cells.
E) plant cells have larger nuclei. → A) nothing; they self-assemble