Deck 18: Manipulating the Genomes of Eukaryotes

Question 1

If integration of DNA provided by pronuclear injection occurs after three cell divisions, the resulting mouse will

A)not contain the transgene in any cells.
B)be a mosaic of cells with some cells containing the transgene and others not.
C)contain the transgene in only germ cells.
D)contain the transgene in only somatic cells.

Answer 1

B

Question 2

What is the purpose of the P element in the creation of transgenic Drosophila?

A)Efficiently transfer DNA into Drosophila chromosomes.
B)Transfer DNA into a specific site in the host chromosome.
C)Transfer DNA only into the nuclei of somatic cells.
D)Transfer DNA only into primitive eye cells.

Answer 2

A

Question 3

What is a possible disadvantage of using genetically modified crops?

A)The transgene may make its way into wild plants.
B)Transgenic strains are typically less robust than the usual strains used for farming.
C)The ability of transgenic plants to use nutrients is reduced so more fertilizer has to be applied.
D)The ability of transgenic strains to use water is poor so these strains are not drought tolerant.

Answer 3

A

Question 4

The coding sequence of the green fluorescent protein gene (GFP)is placed under the control of an enhancer active in neurons.When this transgene is introduced into flies, GFP will be expressed in

A)all neurons or a subset of neurons.
B)all fly cells that have the transgene.
C)all cells in the early embryo and then GFP will be silenced.
D)all cells in the late embryo after neurons form.

Question 5

What is one problem associated with using retroviruses as human gene therapy vectors?

A)Their random integration into the host chromosome may result in detrimental mutations.
B)They need to integrate through an RNA intermediate.
C)The level of proteins produced from them is usually very low.
D)The level of proteins produced from them is usually very high.

Question 6

Why are conditional knockout animals desirable?

A)Genes that are essential for development can be deleted in the adult or only in specific tissues.
B)Animal cell lines with deletions can be created.
C)They are easier to create than standard knockout animals.
D)The mutations they create are more stable than those created by standard knockout techniques.

Question 7

Knockin mice can be created using the Cre/loxP system.In this procedure, the loxP sites are used to

A)delete the neomycin-resistance marker gene.
B)recombine the mutation into the genome.
C)express Cre protein.
D)flip the orientation of genomic DNA after the mutation is inserted.

Question 8

Transgenic organisms are used to clarify which gene may be responsible for a mutant phenotype because

A)individuals with a mutant phenotype can carry mutations in more than one gene.
B)the genes that cause diseases are always dominant.
C)the genes that cause diseases are always recessive.
D)strains used to create transgenic organisms carry no mutations and all their genes are wild-type.

Question 9

Recombinant Ti plasmids allow for

A)the transfer of a transgene from the plasmid in Agrobacterium to a plant cell.
B)transfer of plant DNA to Agrobacterium.
C)the transfer of DNA between two Agrobacterium cells.
D)the transfer of the plasmid from Agrobacterium to E.coli.

Question 10

After exposure to Agrobacterium tumefaciens bacteria containing both a recombinant T-DNA vector and a helper plasmid, new plants can be grown from single cells in the presence of herbicide.Without the herbicide,

A)neither transformed nor nontransformed cells would survive.
B)only nontransformed plants would grow.
C)only cells with the helper plasmid would grow.
D)both transformed and nontransformed plants would grow.

Question 11

To create transgenic mice, DNA is injected into

A)a pronucleus of a zygote.
B)the cytoplasm of a zygote.
C)the nucleus after the pronuclei have fused.
D)a pronucleus of one cell from an embryo.

Question 12

CRISPR sequences occur naturally as

A)an antiviral immune system in bacteria.
B)an antibacterial immune system in eukaryotes.
C)an antiviral immune system in eukaryotes.
D)a gene editing system in bacteria.

Question 13

How can transgenic organisms be used to identify transcriptional enhancers?

A)A reporter gene can be constructed so that its expression is controlled by an enhancer that may potentially exist within a fragment of genomic DNA.
B)A reporter gene can be expressed in every tissue.
C)A gene that is normally expressed in the organism can be cloned under the control of different regulatory elements so that it is expressed in all tissues.
D)A transgene can be integrated in a site that disrupts a gene to determine whether that gene is essential for the cell or organism.

Question 14

Currently the two main vectors for delivery of therapeutic genes for human gene therapy are

A)AAV and retroviruses.
B)AAV and Agrobacterium.
C)Retroviruses and Agrobacterium.
D)AAV and P elements.

Question 15

Transgenic animals made by pronuclear injection can be limited for studies of the links between genes and disease because

A)the transgene allele must be dominant to the normal, endogenous allele and some diseases are caused by recessive mutations.
B)the transgene allele must be recessive to the normal, endogenous allele and some diseases are caused by dominant mutations.
C)all diseases are caused by mutations in multiple genes.
D)diseases are not caused by specific alleles of a gene, but by posttranslational modifications of proteins.

Question 16

A scientist wants to determine whether a mutant phenotype is due to the loss of gene C or gene D, which are both deleted in a mutant fly with abnormal eyes.Mutant flies with transgenic gene C have wild-type eyes, whereas mutant flies with transgenic gene D have abnormal eyes.What can be concluded from these results?

A)Either gene C or gene D is required for normal eye development.
B)Both gene C and gene D are required for normal eye development.
C)Gene C is required for normal eye development.
D)Gene D is required for normal eye development.

Question 17

Pharming refers to the use of transgenic animals and plants to produce protein drugs, such as

A)the production of the blood factor antithrombin III in goat milk.
B)the production of factor VIII protein, the blood-clotting factor, by bacteria.
C)GM plants that have enhanced nutritional value.
D)a transgenic monkey model for Huntington disease.

Question 18

A trait unique to embryonic stem cells that makes them useful for generating knockout animals is that they

A)are totipotent.
B)can be grown in culture.
C)have been isolated from mice.
D)are extremely well characterized at the molecular level.

Question 19

Although bacteria can be used to produce proteins for therapeutic uses, what can be a disadvantage to using a prokaryotic system?

A)Proteins may not be posttranslationally processed correctly.
B)Transcripts from eukaryotic open reading frames are degraded quickly in prokaryotic cells.
C)Some prokaryotic promoters do not work well to transcribe eukaryotic open reading frames.
D)The structures that eukaryotic mRNAs fold into are frequently used as rho termination signals.

Question 20

A researcher has a laboratory strain of flies that have loss-of-function mutations in both gene X and white.These flies are used as hosts for P element transformation: Embryos of the double mutant strain are injected with two plasmids, one containing a wild-type copy of the white gene (w⁺)and a wild-type copy of gene X, side-by-side within P element inverted repeats, and the other plasmid containing only the P element transposase gene.Transgenic offspring of the injected flies will

A)have both plasmids integrated randomly into the genome.
B)have white eyes and express transposase.
C)have red eyes and a wild-type copy of gene X integrated into a random location in the genome.
D)have red eyes and a wild-type copy of gene X in place of the mutant copy in their genome.

Question 21

Fragile X syndrome is a human disease caused by a trinucleotide repeat expansion that results in loss-of-function of the FMR1 gene on the X chromosome.An animal model with most features of this syndrome could be created by

A)adding a transgene containing a mutant copy of the FMR1 gene to a mouse or primate genome.
B)adding a transgene containing a wild-type copy of the FMR1 gene to a mouse or primate genome.
C)knocking out both copies of the FMR1 gene from a mouse or primate genome.
D)knocking out one copy of the FMR1 gene from a mouse or primate genome.

Question 22

Using the CRISPR/Cas9 system, a genetically-engineered sgRNA complementary to a target site in the genome binds to Cas9 endonuclease.A mutation can occur at this site when

A)Cas9 cleaves the DNA and nonhomologous end-joining results in a small deletion.
B)Cas9 cleaves the DNA and homologous recombination with the homologous chromosome is used to repair the break.
C)Cas9 cleaves the DNA to remove the complementary sequence.
D)Cas9 cleaves the DNA and nonhomologous end-joining correctly repairs the break.

Question 23

To generate a knockin mouse, a scientist introduces to ES cells a construct with a mutant exon and within an adjacent intron, loxP sites flanking a neomycin resistance gene.What event will occur next?

A)Homologous recombination between the mutant DNA and the corresponding gene in the mouse genome.
B)Recombination between the loxP sites.
C)Transplantation of cells into host blastocyst.
D)Crossing of heterozygous mice to a Cre-expressing strain.

Question 24

A scientist might create a conditional knockout of a mouse gene when

A)a homozygous loss-of-function mutation in the gene causes embryonic lethality.
B)a homozygous loss-of-function mutation in the gene produces a wild-type phenotype.
C)a homozygous loss-of-function mutation in the gene affects only ears.
D)a homozygous loss-of-function mutation in the gene affects only coat color.

Question 25

Huntington disease is caused by expansion of the trinucleotide repeat region of the HD gene that results in the production of a Huntingtin protein with an expanded number of glutamines.An animal model with most features of this syndrome could be created by

A)adding a transgene containing a disease-causing mutant allele of the HD gene to a mouse or primate genome.
B)adding a transgene containing a wild-type copy of the HD gene to a mouse or primate genome.
C)knocking out both copies of the HD gene from a mouse or primate genome.
D)knocking out one copy of the HD gene from a mouse or primate genome.

Question 26

The disease Leber congenital amaurosis (LCA), caused by loss-of-function mutation of a gene called RPE65, has been treated with gene therapy by injecting recombinant AAV vectors containing a normal copy of the RPE65 gene into their retinal epithelial cells.Patients receiving this therapy

A)may acquire detrimental mutations due to integration of the virus.
B)may need to repeat the treatment as the viral DNA is degraded.
C)will pass the mutation to their offspring.
D)now have the normal RPE65 gene in all cells.

Question 27

To create a knockout mouse, after introducing to ES cells a DNA construct in which a specific gene is mutagenized by the insertion of a drug resistance marker, the cells

A)that have incorporated the transgene by homologous recombination grow in the presence of the drug and these are injected into a host blastocyst.
B)that lack the transgene grow in the presence of the drug and these are injected into a host blastocyst.
C)that have deleted the transgene grow in the presence of the drug and the nuclei are injected into a host blastocyst.
D)that lack the transgene grow in the presence of the drug and the nuclei are used for nuclear transfer.

Question 28

The FDA-approved GM Atlantic salmon have a growth hormone transgene that is expressed year-round, which is advantageous because

A)the salmon is more nutritious.
B)the salmon achieve their full weight faster.
C)the salmon produce more offspring.
D)the salmon are more resistant to infection.