5 Written questions
5 Matching questions
- To cause a human pandemic, the H5N1 avian flu virus would have to
A) become much more pathogenic.
B) spread to primates such as chimpanzees.
C) arise independently in chickens in North and South America.
D) become capable of human-to-human transmission.
E) develop into a virus with a different host range.
- The role of a metabolite that controls a repressible operon is to
A) bind to the promoter region and decrease the affinity of RNA polymerase for the
B) bind to the repressor protein and inactivate it.
C) bind to the operator region and block the attachment of RNA polymerase to the promoter.
D) increase the production of inactive repressor proteins.
E) bind to the repressor protein and activate it.
- In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells?
A) Cytoplasm from embryonic cells is injected into the adult cells.
B) An adenovirus vector is used to transfer embryonic gene products into adult cells.
C) The nucleus of an embryonic cell is used to replace the nucleus of an adult cell.
D) A retrovirus is used to introduce four specific regulatory genes.
E) The adult stem cells must be fused with embryonic cells.
- Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?
A) Eukaryotic exons may be spliced in alternative patterns.
B) Prokaryotic genes are expressed as mRNA, which is more stable in the cell.
C) Eukaryotic mRNAs get 5' caps and 3' tails.
D) Prokaryotes use ribosomes of different structure and size.
E) Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.
- Which of the following best describes siRNA?
A) a molecule, known as Dicer, that can degrade other mRNA sequences
B) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
C) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits
D) a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns
E) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor
- a B) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
- b D) A retrovirus is used to introduce four specific regulatory genes
- c E) bind to the repressor protein and activate it
- d D) become capable of human-to-human transmission
- e A) Eukaryotic exons may be spliced in alternative patterns
5 Multiple choice questions
- A) the ampicillin broth and the nutrient broth
- D) rabies
- 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.
- A) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate
- B) host cell DNA polymerase
5 True/False questions
Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?
A) Viruses are enclosed in protein capsids rather than plasma membranes.
B) Viruses contain either DNA or RNA.
C) Viral genomes are usually similar to the genome of the host cell.
D) Viruses can reproduce only inside host cells.
E) Viruses can infect both prokaryotic and eukaryotic cells. → B) RNA polymerase must bind to the promoter, and the repressor must be inactive
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
In the figure, when new viruses are being assembled (IV), what mediates the assembly?
A) nothing; they self-assemble
B) host cell chaperones
C) viral RNA intermediates
D) assembly proteins coded for by the viral genes
E) assembly proteins coded for by the host nucleus → D) apoptosis of a virally infected cell
Genomic imprinting, DNA methylation, and histone acetylation are all examples of
A) chromosomal rearrangements.
B) epigenetic phenomena.
E) genetic mutation. → B) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication
A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. Within the first quarter hour, the researcher sees that the intact RNA is found in the cells. After 3 hours, she is not surprised to find that
A) the double-stranded RNA binds to mRNAs to prevent translation.
B) the double-stranded RNA replicates itself.
C) the RNA is degraded by 5' and 3' exonucleases.
D) Dicer enzyme has reduced it to smaller double-stranded pieces.
E) the double-stranded RNA binds to tRNAs to prevent translation. → C) a YAC with appropriate cellular enzymes