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WorksheetsH & G Molecular Genetics
Total questions: 20
Worksheet time: 12mins
Which of the following has a DNA genome surrounded by a protein coat?
a retrovirus
a virus
a eukaryotic cell
a prokaryotic cell
Which of the following is a laboratory application of restriction enzymes?
to block replication of DNA
to artificially force the transcription of DNA
to prevent the translation of mRNA
to cut DNA molecules at specific locations
When a virus infects a bacterium by injecting its DNA and the genome of the virus incorporated into the host cell, this is
the lytic cell of a phage
the lysogenic cell of a phage
transposition by a virus
retroviral infection
When the electric field was applied, the fragments of DNA in each of the three samples migrated to different locations along the gel. Which of the following explains the pattern shown here?
The fragments differed in levels of radioactivity.
The fragments differed in charges.
The fragments differed in size.
The fragments differed in solubility.
How many sites on DNA were cut by the particular restriction enzyme used in Sample 1 (far left?
6
7
8
9
A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced by lysis of infected cells would have:
T2 protein an T4 DNA.
T2 protein and T2 DNA.
T4 protein and T4 DNA.
T4 protein and T2 DNA.
A mobile segment of DNA that travels from one location on a chromosome to another:
Transcription
Translation
Transposon
DNA methylation
The addition of chemical groups to certain DNA bases after DNA synthesis:
Transcription
Translation
Transposon
DNA methylation
The synthesis of polypeptides from the genetic information coded in mRNA
Transcription
Translation
Transposon
DNA methylation
The synthesis of RNA from a DNA template:
Transcription
Translation
Transposon
DNA methylation
RNA retroviruses such as HIV discharge both strands of RNA and molecules of reverse transcriptase into cells they infect. What is the purpose of the reverse transcriptase?
The host cells rapidly destroy the viral RNA so more must constantly be made.
The host cells lack enzymes that can replicate the viral genome.
The reverse transcriptase is required to translate viral mRNA into proteins.
The reverse transcriptase binds to active sites of the lytic enzymes of the host cells.
Which of the following mutation events would have the most significant effect on the resulting polypeptide?
A nucleotide and its complementary base are replaced, resulting in a new amino acid in translation.
A nucleotide pair is added into a gene near its terminal end, altering the reading frame of the genetic message.
A nucleotide pair substitution occurs, which results in the introduction of a "stop" codon.
A nucleotide is altered that results in no change in the amino acid sequence due to redundancy.
The human genome appears to have only about as many genes as the simple nematode worm, C. elegans. Which of the following best explains how the more complex humans can have relatively few genes?
Human genes have unusually long introns involved in the regulation of gene expression.
More than one polypeptide can be produced from a gene by alternative splicing.
The human genome has a high proportion of noncoding DNA.
The human genome has a large number of single nucleotide polymorphisms, which increases genetic variability.
The most likely method by which the mutated CCR5 gene prevents AIDS is by
blocking the protein channels that allow the virus to enter the cell.
directing the formation of lytic enzymes packaged in the lysosomes.
being presented on immune system cells to target the virus for attack and destruction.
coding for a mutant receptor protein on the cell membrane, thus not allowing the entry of the virus.
An example of a post-transcriptional modification:
tRNA
mRNA
Poly-A tail
RNA polymerase
Binds to the promoter on DNA to initiate transcription:
tRNA
mRNA
Poly-A tail
RNA polymerase
Binds to free amino acids in the cytoplasm:
tRNA
mRNA
Poly-A tail
RNA polymerase
Travels out of the nucleus and into the cytoplasm where it serves as a template in translation:
tRNA
mRNA
Poly-A tail
RNA polymerase
Lateral gene transfer involves the movement of genes between members of a species without sexual reproduction. In bacteria, there are three mechanisms for this: conjugation, transformation, and transduction. Predict how these processes are most likely to affect bacteria.
Their DNA content will be reduced.
The amount of RNA in the cytoplasm will be increased.
Their genetic diversity will increase.
Their metabolic needs will be modified to give a selective advantage.
How are the leading and lagging strands of DNA synthesized differently?
Origins of replication can only occur at the 5' end.
Helicases and DNA polymerase work at the 5' end.
DNA polymerase can join new nucleotides only to the 3' end of a growing strand.
DNA ligase works only in the 3' to 5' direction.
