Mol Gen Exam 4 Multiple Choice

Which of the below is not true about the location of enhancers?

The position of the enhancer has no effect on gene regulation.

When referring to attenuation in regulation of the tryptophan operon, it would be safe to say that when there are high levels of tryptophan available to the organism,

Transcriptional termination is likely

In what way do upstream activator sequences (UASs), regulatory sequences in yeast, differ from enhancers and silencers?

UASs only function upstream.

The following may be caused by mobile genetic elements except ________________

Undergo Mutation

One speaks of UAS (upstream activating sequences) as being DNase hypersensitive. We would interpret this to mean that

a UAS is constitutively open.

Conditional mutations are more likely to result from which of the following alterations to the coding region of a gene.

a mutation caused by a tautomeric shift

What modification neutralizes the charges on histones that promote ionic interaction with DNA?

acetylation

Assuming one mutational event in a gene, on average, which of the following mutagens would be expected to cause the most damage to a protein synthesized by such a mutagenized gene?

acridine orange

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation refers to

addition of methyl groups to the cytosine of CG doublets.

In what part of the mRNA does degradation generally begin?

at the 5' end with the removal of the methyl cap

The lac repressor protein controls expression of the lac operon via ________________

binding to the lac operator site to repress expression

Which of the following clusters of terms applies when addressing enhancers or silencers as elements associated with eukaryotic genetic regulation?

cis-acting, variable orientation, variable position

Which of the following are general categories of mutations? Select all that apply.

conditional, behavioral, lethal

LINES differ from retrotransposons in that LINES:

do not contain LTRs.

Considering the location of genes in the interphase nucleus, certain chromosomal territories appear to exist. Specifically,

each chromosome appears to occupy a discrete domain.

Regulation of gene expression using siRNAs is found in

eukaryotes only

A class of mutations that results in multiple contiguous amino acid changes in proteins is likely to be the following:

frameshift

Which of these are major structural classifications of DNA-binding domains that are found in eukaryotic transcription factors? Please select all that apply:

helix-turn-helix zinc finger leucine zipper

Channels between chromosomes in the interphase nucleus are called

interchromosomal compartments.

A mutant E. coli strain, grown under conditions that normally induce the lac operon, produces high amounts of ß-galactosidase. What is a possible genotype of the cells?

lacI+ lacP+ lacOc lacZ+ lacY+ lacA+ (they're all +)

A mutant E. coli strain, grown under conditions that normally induce the lac operon, does not produce ß-galactosidase. What is a possible genotype of the cells?

lacI+ lacP- lacO+ lacZ+ lacY+ lacA+

Which of the following are general categories of mutations? Select all that apply. morphological DNA induced protein-altering regulatory

morphological, regulatory, induced

Choose the type of control illustrated by each example. E. coli lac operon control by lac I

negative inducible

An operon is controlled by a repressor. When the repressor binds to a small molecule, it binds to DNA near the operon. The operon is constitutively expressed if a mutation prevents the repressor from binding to the small molecule.

negative repressible

Assume that you wished to generate conditional mutations (such as temperature sensitive mutations) for the study of cell-cycle genes in yeast. Of the mutagens listed in the following, which would be the most likely to generate such mutations?

nitrosoguanidine ethyl methane sulfonate (EMS)

A _________ mutation changes a codon that specifies an amino acid into one that terminates translation.

nonsense

What term refers to a contiguous genetic complex that is under coordinate control?

operon

A conditional mutation is one that allows a mutant gene product to function normally under the ________ condition, but to function abnormally under the ________ condition. Such mutations are especially useful for the study of ________ mutations.

permissive; restrictive; lethal

Which of the following terms best characterizes catabolite repression associated with the lactose operon in E. coli?

positive control

Which of these is a level of regulation in eukaryotes? Select all that apply:

processing transport transcriptional post-translational

What is the general position of the consensus sequence called the GC box? What is its sequence?

promoter; GGGCGG

An example of a gene product encoded by a regulatory gene is

repressor protein.

Under certain conditions, the rate of mutation of a particular gene may be determined in humans. What properties of the mutation would favor the most direct determination of mutation rate in humans? Select all that apply:

single locus 100% penetrant fully expressed dominant

In the lactose operon, the product of structural gene lacZ is capable of

splitting the β-linkage of lactose.

In general, a "model organism" used in genetics studies is one in which there is a large body of genetic knowledge that has been compiled over decades of genetic research. In addition, model organisms have available their DNA sequences and collections of ________ that make detailed genetic analysis possible and efficient.

strains with specific mutations

siRNAs and miRNAs are produced by

the cutting and processing of double-stranded RNA by Dicer enzymes

Alternative splicing is known to be important in the regulation of

the mammalian SV40 virus.

It is possible for a repressor to negatively regulate the expression of an operon because

the repressor binding site overlaps the promoter site of the operon allowing it to physically block the binding of RNA polymerase.

This question relates to the regulation of enzymes involved in the synthesis of tryptophan in E. coli. If tryptophan is present in the medium and available to the bacterium,

the repressor is bound to the operator, thus blocking transcription

Insulators can block the effects of enhancers only when

they lie between an enhancer and a promoter.

Nutritional mutations can be defined as

those mutations which do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium.

Genetic regulation in eukaryotes can take place at a variety of levels from transcriptional to post-translational. At what level is genetic regulation considered most likely in prokaryotes?

transcriptional

Regarding eukaryotic and prokaryotic genetic regulation, what process seems to be the most similar between the two?

transcriptional regulation

Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are called

transversions and transitions.

Considering the electromagnetic spectrum, identify likely mutagens from the following list: radio waves, microwaves, infrared, ultraviolet, X rays, gamma rays, cosmic rays.

ultraviolet, gamma rays, cosmic rays, and x-rays

The difference between a genetic screening experiment and a selection experiment is that a screening experiment involves ________, whereas a selection experiment creates conditions that ________ irrelevant organisms.

visual examination; eliminate

Under the system of genetic control of the tryptophan operon,

when there is no tryptophan in the medium, transcription of the trp operon occurs at high levels.

A new mutagen is able to cause frameshift mutations. Which kind of mutagen could be capable of reversing this mutation?

Intercalating Agent

What is the function of cAMP in regulation of the lac operon?

It activates an activator protein.

Choose the type of control illustrated by each example. E. coli lac operon control by lac I

Negative inducible

Mutations that arise in nature, from no particular artificial agent, are called

Spontaneous Mutations

Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from

xeroderma pigmentosum.

Riboswitches were first discovered in 2002 and have been found in...

(All listed organisms) bacteria, archaea, plants, fungi

In the absence of glucose and in the presence of galactose, several genes are activated to enable yeast utilize galactose. The key regulator(s) of the yeast GAL system is/are the _______ protein(s).

(All of the above) - Gal4 - Gal80 - Gal3

After translation, eukaryotic proteins can be modified by

(all of the above) the addition of phosphate groups. acetylation. the removal of amino acids. the addition of methyl groups.

Which of these is a level or type of genetic regulation in eukaryotes? Select all that apply:

-post-translational -transcriptional -DNA Methylation

Drosophila melanogaster has approximately ________ genes on its ________ pairs of chromosomes.

13,600; 4

Name two mutagens that would be classified as base analogs.

5-bromouracil and 2-aminopurine

It is estimated that transposable elements compose approximately what percent of the human genome?

50%

Of the approximately 6600 genes in Saccharomyces cerevisiae, about ________ have a known function.

5700

Assuming one mutational event in a gene, on average, which of the following mutagens would be expected to cause the most damage to a protein synthesized by such a mutagenized gene?

Acridine Orange

Assume that you wished to generate conditional mutations (such as temperature sensitive mutations) for the study of cell-cycle genes in yeast. Of the mutagens listed in the following, which would be the most likely to generate such mutations?

B & C (EMS and Transposon Insertion)

Regulatory proteins that bind DNA have common motifs that interact with sequences of DNA. How do amino acids in DNA-binding proteins interact with DNA?

By forming hydrogen bonds with DNA bases

Which term most appropriately refers to a regulatory protein in prokaryotes?

DNA Binding Protein

__________ mutations produce new traits and are usually dominant.

Gain-of-function

DNA may be damaged from the by-products of normal cellular aerobic respiration. Name three of these electrophilic oxidants that are generally classified as reactive oxidants.

Hydroxyl Radicals (OH) Hydrogen Peroxide (H2O2) Superoxides (O2)

Which of the following is NOT true regarding the differences in mRNA between prokaryotic cells and eukaryotic cells?

In eukaryotic cells, the transcription to mRNA and the translation from mRNA are coupled, while in prokaryotic cells transcription and translation are not coupled.

The lac repressor binds to:

Lactose and DNA.

What term would be applied to a regulatory condition that occurs when protein greatly reduces transcription when associated with a particular section of DNA?

Negative Control

An operon is controlled by a repressor. When the repressor binds to a small molecule, it is released from binding to DNA near the operon. The operon is never expressed if a mutation prevents the repressor from binding to the small molecule.

Negative Inducible

E. coli bacteria are placed into a medium containing glucose and lactose. Which of the genes below do you expect to be turned on?

None of the above

Which of the following is TRUE for both prokaryotic and eukaryotic gene expression?

RNA polymerase binds to the promoter region to begin transcription

siRNA and miRNA inhibit gene expression by all of the following EXCEPT

Stabilizing translation machinery

In general, a "model organism" used in genetics studies is one in which there is a large body of genetic knowledge that has been compiled over decades of genetic research. In addition, model organisms have available their DNA sequences and collections of ________ that make detailed genetic analysis possible and efficient.

Strains with specific mutations

Two modular elements that appear as consensus sequences upstream from RNA polymerase II transcription start sites are

TATA and CAAT.