Concept of Genetics Ch 16

DNA is methylated on which nucleotides? guanine cytosine adenine thymine uracil

cytosine

T/F A repressor regulates gene expression in a negative control, while an activator regulates gene expression in a positive control

T

T/F There is an inversed relationship between glucose level and cAMP level in bacteria

T

Two modular elements that appear as consensus sequences upstream from RNA polymerase II transcription start sites are ________. microsatellites and transposons rDNA and nucleolar organizers TATA and CAAT TTAA and CCTT enhancers and telomeres

TATA and CAAT

A lack of this nonprotein molecule would result in the inability of the cell to ʺturn offʺ genes: operon inducer promoter repressor corepressor

corepressor

There are ....................structural genes in lac operon.

3

In the repressible system, a/an in the positive control the transcription to occur in the absence of a co-repressor.

Active activator; allows

Why is transcriptional control of gene expression more difficult in eukaryotes than in prokaryotes? 1. Genes are sequestered in the nucleus. 2. Eukaryotic cells need fairly elaborate internal signaling systems to control the transcription of DNA 3. Environmental cues may have to pass through layers of cells in order to have an impact on the transcription of genes in a particular tissue. 1 2 3 1 and 2 All of these are correct.

All of these are correct

Allolactose induces the synthesis of the enzyme lactase. 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? The repressor protein attaches to the regulator. Allolactose binds to the repressor protein. Allolactose binds to the regulator gene. The repressor protein and allolactose bind to RNA polymerase. RNA polymerase attaches to the regulator.

Allolactose binds to the repressor protein

This protein is produced by a regulatory gene: operon inducer promoter repressor corepressor

repressor

Which of the following statements is correct? Prokaryotes undergo processing after transcription and eukaryotes do not. Eukaryotes undergo processing after transcription and prokaryotes do not. Prokaryotes undergo transcription but eukaryotes do not. Eukaryotes undergo transcription but prokaryotes do not. There are no differences between the expression of genes in prokaryotes and eukaryotes.

Eukaryotes undergo processing after transcription and prokaryotes do not.

T/F In a positive control, gene expression occurs unless it is shut off by a repressor.

F

T/F The lac operon is subject to negative control when an activator binds to the promoter and allows the transcription to occur.

F

T/F The repressor is allosteric. It means that it binds permanently to the operator region of lac operon and blocks the transcription

F

Which of the following is true about histone acetyltransferase (HAT)? HATs will remove acetyl groups from histone proteins. HATs will add acetyl groups to DNA. HATs will make the chromatin more compacted and less available to transcription regulatory proteins. HATs are usually linked to increasing gene expression. HATs have an overall effect of increasing the positive charges on DNA.

HATs re usually linked to increasing gene expression

In the inducible system, a in the negative control or a/n in the positive control............. allows the transcription to happen in presence of an inducer.

Inactive repressor; active activator

How does active CAP induce expression of the genes of the lactose operon? It terminates production of repressor molecules. It degrades the substrate allolactose. It stimulates splicing of the encoded genes. It stimulates the binding of RNA polymerase to the promoter. It binds steroid hormones and controls translation.

It stimulates the binding of RNA polymerase to the promoter.

For a repressible operon to be transcribed, which of the following must occur? A corepressor must be present. RNA polymerase and the active repressor must be present. RNA polymerase must bind to the promoter, and the repressor must be inactive. RNA polymerase cannot be present, and the repressor must be inactive. RNA polymerase must not occupy the promoter, and the repressor must be inactive.

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

In the inducible system, a and a/n block the transcription in the negative and positive controls respectively in absence of an inducer

Repressor, inactive activator

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 gene), which of the following would likely occur when the cell is exposed to lactose? The inducer will no longer bind to the repressor. The repressor will no longer bind to the operator. The operon will never be transcribed. The structural genes will be transcribed continuously. The repressor protein will no longer be produced.

The structural genes will be transcribed continuously.

In what way do upstream activator sequences (UASs), regulatory sequences in yeast, differ from enhancers and silencers? UASs function only downstream. UASs function only upstream. Enhancers function only downstream. UASs function in the middle of transcription units. UASs can function only in the 5'-3' direction

UASs function only upstream.

At which level is the gene expression of eukaryotes regulated? Transcription Post-transcriptional processing Translation Transcription and post-transcriptional processing All of these are correct.

all of these are correct

UASs (upstream activating sequences) are DNase hypersensitive. This means that ____. a UAS is constitutively open more than one strand of DNA exists in each UAS each UAS is likely to be single-stranded each UAS has more histone binding sites than non-UAS sites any given UAS is composed of a double-stranded site with a bound repressor

a UAS is constitutively open

Regulation of the inducible or repressible system in general can be controlled by........... a negative control a positive control a positive or negative control none

a positive or negative control

When an inducer is present, the gene expression is

active

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation refers to ________. altering RNA polymerase activity by DNA modifications changes in DNA-DNA hydrogen binding altering translational activity especially of highly methylated tRNAs alteration of DNA polymerase activity by addition of methyl groups to glycine residues addition of methyl groups to the cytosine of CG doublets

addition of methyl groups to the cytosine of CG doublets

Altering patterns of gene expression in prokaryotes would most likely serve the organismʹs survival in which of the following ways? organizing gene expression so that genes are expressed in a given order allowing each gene to be expressed an equal number of times allowing the organism to adjust to changes in environmental conditions allowing young organisms to respond differently from more mature organisms allowing environmental changes to alter the prokaryoteʹs genome

allowing the organism to adjust to changes in environmental conditions

In response to chemical signals, prokaryotes can do which of the following? turn off translation of their mRNA alter the level of production of various enzymes increase the number and responsiveness of their ribosomes inactivate their mRNA molecules alter the sequence of amino acids in certain proteins

alter the level of production of various enzymes

In the presence of both glucose and lactose, the genes of lac operon

are inactive (off)

An enzyme that is responsible for breaking down lactose to glucose and galactose is

beta-galactosidase

The role of a metabolite that controls a repressible operon is to -bind to the promoter region and decrease the affinity of RNA polymerase for the promoter. -bind to the operator region and block the attachment of RNA polymerase to the promoter. -increase the production of inactive repressor proteins. -bind to the repressor protein and inactivate it. -bind to the repressor protein and activate it.

bind to the repressor protein and activate it.

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 trans-acting, fixed position, fixed orientation cis-acting, fixed position, fixed orientation cis-acting, variable position, fixed orientation trans- and cis-acting, variable position

cis-acting, variable orientation, variable position

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in continuous transcription of the structural gene controlled by that regulator. complete inhibition of transcription of the structural gene controlled by that regulator. irreversible binding of the repressor to the operator. inactivation of RNA polymerase by alteration of its active site. continuous translation of the mRNA because of alteration of its structure.

continuous transcription of the structural gene controlled by that regulator.

lactose is a .

di-saccharide

An inducible system can be regulated by

either a positive control or a negative control

lactose is composed of and

galactose; glucose

In the repressible system, a/an in the negative control............ the transcription to occur in the absence of a co-repressor.

inactive repressor; allows

Lactose functions as a/an in lac operon

inducer

When this is taken up by the cell, it binds to the repressor so that the repressor no longer binds to the operator: operon inducer promoter repressor corepressor

inducer

Which of the following are truth regarding the binding of a trans-acting element at a cis-acting site?

it regulates either negatively or positively

Whenever the RNA within the RISC pairs imperfectly with its target sequence, the mRNA is usually not cleaved; instead, translation of the mRNA is inhibited. RISC-associated RNAs that have this effect are usually termed siRNAs. miRNAs. SNRPs. mtDNAs. STRs.

miRNAs

Which 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 positive control inhibition activation stimulation

negative control

If gene expression is regulated at the transcriptional level, where in a eukaryotic cell does this regulation take place? Nucleus Mitochondria Rough ER Ribosome Cytoplasm

nucleus

Where does RNA transcript modification occur in eukaryotic cells? Nucleus Mitochondria Rough ER Lysosome Ribosome

nucleus

Which component of a eukaryotic cell can serve as the location for regulation of gene expression? Nucleus Cytoplasm Mitochondria Nucleus and cytoplasm All of these are correct

nucleus and cytoplasm

Which term refers to a contiguous genetic complex that is under coordinate control? lysogen prototroph operon allosteric attenuation

operon

A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA: operon inducer promoter repressor corepressor

promotor

Which of the following molecules participates in RNA interference? siRNA tRNA rRNA dsDNA All of these are correct

siRNAs

Which of the following would not induce eukaryotic gene expression? Heat Light Hormones siRNAs Growth factors

siRNAs

What type of DNA sequence a repressor protein be expected to bind? silencer enhancer insulator TATA Box GC Box

silencer

In the lactose operon, the product of structural gene lacZ is capable of ________. nonautonomous replication forming lactose from two glucose molecules replacing hexokinase in the early steps of glycolysis splitting the β-linkage of lactose forming ATP from pyruvate

splitting the β-linkage of lactose

Transcription of the structural genes in an inducible operon occurs continuously in the cell. starts when the pathwayʹs substrate is present. starts when the pathwayʹs product is present. stops when the pathwayʹs product is present. does not result in the production of enzymes.

starts when the pathwayʹs substrate is present

What does the operon model attempt to explain? -the coordinated control of gene expression in bacteria -bacterial resistance to antibiotics -how genes move between homologous regions of DNA -the mechanism of viral attachment to a host cell -horizontal transmission of plant viruses

the coordinated control of gene expression in bacteria

The lactose operon is likely to be transcribed when there is more glucose in the cell than lactose. the cyclic AMP levels are low. there is glucose but no lactose in the cell. the cyclic AMP and lactose levels are both high within the cell. the cAMP level is high and the lactose level is low.

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

The protein-DNA interactions that control whether or not a gene is accessible to RNA polymerase occur during which phase of gene expression? Replication Transcription Translation Replication and transcription Transcription and translation

transcription

Positive and negative regulator proteins that bind to specific regions of the DNA and stimulate or inhibit transcription in eukaryotes are known as transcription inhibitors. transcription factors. unit factors. translation regulators. None of these are correct.

transcription factors

Which process seems to be the most similar between eukaryotic and prokaryotic genetic regulation? transcriptional regulation RNA splicing regulation intron/exon shuffling 5'-capping regulation poly(A) tail addition

transcription regulation

Genetic regulation in eukaryotes can take place at a variety of levels from transcriptional to posttranslational. At which level is genetic regulation considered most likely in prokaryotes? transcriptional capping polyadenylation of the 3' end of the mRNAs intron processing exon processing

transcriptional

The tryptophan operon is a repressible operon that is permanently turned on. turned on only when tryptophan is present in the growth medium. turned off only when glucose is present in the growth medium. turned on only when glucose is present in the growth medium. turned off whenever tryptophan is added to the growth medium.

turned off whenever tryptophan is added to the growth medium.