5 Written questions
5 Matching 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
If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?
E) either II or IV
- If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then
A) the amino acid inactivates the repressor.
B) the amino acid acts as a corepressor.
C) the repressor is active in the absence of the amino acid.
D) the enzymes produced are called inducible enzymes.
E) the amino acid turns on transcription of the operon.
- CML (chronic myelogenous leukemia) results from a translocation between human chromosomes 9 and 22. The resulting chromosome 22 is significantly shorter than usual, and it is known as a Philadelphia (Ph') chromosome. The junction at the site of the translocation causes overexpression of a thymine kinase receptor. A new drug (Gleevec or imatinib) has been found to inhibit the disease if the patient is treated early.
Why would Gleevec most probably cause remission of the disease? A) The drug inhibits the replication of the affected chromosome.
B) It eliminates the Ph' chromosome. C) It removes Ph'-containing progenitor cells.
D) It reverses the chromosomal translocation.
E) The drug inhibits the specific thymine kinase receptor.
- One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy?
A) The engineered bone marrow cells from this patient can be used for any other SCID patient.
B) No vector is required to introduce the allele into ADA-negative cells.
C) The engineered cells, when reintroduced into the patient, find their way back to the bone
D) The ADA-introduced allele causes all other ADA-negative cells to die.
E) The immune system fails to recognize cells with the variant gene.
- 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
- a C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow
- b B) the amino acid acts as a corepressor
- c D) to sequence a DNA fragment
- d E) The drug inhibits the specific thymine kinase receptor.
- e C) III
5 Multiple choice questions
- B) Transferred genes may not have appropriately controlled activity
- E) Beta galactosidase will be produced
- B) interference with viral replication
- C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones
- D) misfolded versions of normal brain protein
5 True/False questions
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 → D) no AUG in any frame
A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that
A) bacterial RNA polymerase cannot make RNA complementary to mammalian DNA.
B) bacteria cannot remove eukaryotic introns.
C) prokaryotes use a different genetic code from that of eukaryotes.
D) bacterial DNA is not found in a membrane-bounded nucleus and is therefore
incompatible with mammalian DNA. E) bacteria translate polycistronic messages only. → A) T4 protein and T4 DNA
A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. Which of the following results would she most likely see?
A) increased chromatin condensation
B) decreased chromatin condensation
C) inactivation of the selected genes D) decreased binding of transcription factors
E) abnormalities of mouse embryos → E) bind to complementary regions of target mRNAs
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 a positive RNA strand as its genome, it begins the infection by using this strand as mRNA. Therefore, which of the following do you expect to be able to measure?
A) translation rate
B) formation of new transcription factors
C) accumulation of new ribosomes D) transcription rate
E) replication rate → E) retroviruses
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?
E) E → D) D