question

The role of a metabolite that controls a repressible operon is to

answer

bind to the repressor protein and activate it.

question

The tryptophan operon is a repressible operon that is

answer

turned off whenever tryptophan is added to growth medium

question

Which of the following is a protein produced by a regulatory gene?

answer

Repressor

question

A lack of which molecule would result in the cell's inability to "turn off" genes?

answer

Corepressor

question

Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?

answer

Inducer

question

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?

answer

Inducer

question

A mutation that inactivates the regulatory gene of a repressible operon in an E.Coli cell would result in

answer

continuous transcription of the structural gene controlled by that regulator

question

The lactose operon is likely to be transcribed when

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the cyclic AMP and lactose levels are both high within the cell

question

Transcription of the structural genes in an inducible operon

answer

starts when the pathway's substrate is present.

question

For a repressible operon to be transcribed, which of the following must occur?

answer

RNA polymerase must bind to the promoter, and the repressor must be inactive

question

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. Coli cell is presented for the first time with the sugar lactose, containing allolactose, as a potential food source. Which of the following occurs when the lactose enters the cell?

answer

Allolactose binds to the repressor protein.

question

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

answer

allowing the organism to adjust to changes in environmental conditions

question

In response to chemical signals, prokaryotes can do which of the following?

answer

alter the level of production of various enzymes

question

In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP?

answer

decrease in glucose and increase in cAMP

question

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant?

answer

It cannot bind to the inducer.

question

Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells?

answer

A specific combination of control elements in each gene's enhancer coordinates the simultaneous activation of the genes.

question

If you were to observe the activity of methylated DNA, you would expect it to

answer

have turned off or slowed down the process of transcription

question

Genomic imprinting, DNA methylation, and histone acetylation are all examples of

answer

epigenetic phenomena

question

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity?

answer

methylation and phosphorylation of histone tails

question

Two potential devices that eukaryotic cells use to regulate transcription are

answer

DNA methylation and histone modification

question

During DNA replication,

answer

methylation of DNA is maintained because methylation enzymes act at DNA sites where one stand is already methylated and thus correctly methylates daughter strands after replication.

question

In eukaryotes, general transcription factors

answer

bind to other proteins or to a sequence element within the promoter called the TATA box.

question

Steroid hormones produce their effects in cells by

answer

binding to intracellular receptors and promoting transcription of specific genes

question

Transcription factors in eukaryotes usually have DNA binding domains as well as other domains that are also specific for binding. In general, which of the following would you expect many of the to be able to bind?

answer

other transcription factors

question

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?

answer

Eukaryotes exons may be spliced in alternative patterns

question

Which of the following is most likely to have a small protein called ubiquitin attached to it?

answer

A cyclin that usually acts in G1, now that the cell is in G2

question

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called

answer

RNA interference

question

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for most of the rest?

answer

non-protein coding DNA that is transcribed into several kinds of small RNAs with biological function

question

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and blocks expression of some transposons. These are known as

answer

piRNA

question

Which of the following best describes siRNA

answer

A short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

question

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

answer

targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease

question

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still be explained?

answer

Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible

question

You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of you first questions is whether the gene's expression is controlled at the level of transcription or translation. Which of the following might best give you an answer?

answer

You measure the quantity of the appropriate pre-mRNA in various ell types and find they are all the same

question

In a genome-wide expression study using a DNA microarray assay, each well is used to detect the

answer

expression of a specific gene by a cell

question

DNA microarrays have had a huge impact on genomic studies because they

answer

allow the expression of many or even all the genes in a genome to be compared at once

question

Researchers are looking for better treatments for breast cancer. For a particular DNA microarray (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for a

answer

pattern shared among some or all of the samples that indicates gene expression differing from control samples

question

Which one of the following techniques involves reverse transcriptase, PCR amplification, and gel electrophoresis?

answer

RT-PCR

question

In the microarray shown *Figure 15.1,* if you were searching for genes whose expression was inhibited by hormone treatment, you would search for sequences spotted on the array that show _______ fluorescence.

answer

no

question

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following would be likely?

answer

The operon will not be produced

question

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following would likely occur when the cell is expose to lactose?

answer

The structural genes will be transcribed continuously

question

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the respressor gene (lac I), along with its promoter, to a position some several thousand base pairs away from its normal position, which will you expect to occur?

answer

The lac operon will function normally

question

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Which of the following is a likely explanation for the lack of transgene expression in the fifth cell line?

answer

The transgene integrated into a heterochromatic region of the genome

question

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Of the lines that express the transgene, one is transcribed but not translated. Which of the following is a likely explanation?

answer

no AUG in any frame

question

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the following results would she most likely see?

answer

decreased chromatin condensation

question

One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see?

answer

inactivation of the selected genes

question

In one set of experiments using this procedure in Drophilia, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see?

answer

decreased chromatin condensation

question

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its small subsections experimentally, using a fluorescent probe. In addition, she finds what other evidence of this single stranded RNA piece's activity?

answer

The rate of accumulation of the polypeptide encoded by the target mRNA is reduced.

question

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

answer

the amino acid acts as a corepressor

question

The functioning of enhancers is an example of

answer

transcriptional control of gene expression

question

Which of the following is an example of post transcriptional control of gene expression?

answer

the removal of intros and alternative splicing of exons

question

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?

answer

continuous transcription of the operon's genes

question

Which of the following statements about the DNA in one of your brain cells in true?

answer

It is the same as the DNA in one of your kidney cells

question

Which of the following would not be true of cDNA produced using human brain tissue as the starting material?

answer

It would contain sequences representing all the genes in the genome

Campbell Biology in Focus, Chapter 15 Regulation of Gene Expression – Flashcards

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