draft chapter 14 gene regulation in bacteria

what kind of genes encode proteins that are needed for bacterium survival

constitutive genes

which data provide the strongest evidence that O1 is not the only operator site?

data where O2 and O3 are deleted indicate O1 by itself is not the only operator site

refers to control of proteins already present in the cell:

posttranslational regulation

a repressor is a _______ that ________ transcription

regulatory protein, inhibits

An RNA molecule that can exist in two different secondary conformations and thereby affect gene regulation is known as a(n)

riboswitch

a _____ is a protein that influences the ability of RNA polymerase to transcribe a given gene.

transcription factor

Studies indicate that the lac operon has ______ operator site(s) for the lac repressor.

3

What effect can ATP-dependent chromatin remodeling have on transcription? Neither activation nor repression Both activation and repression Activation only Repression only

Both activation and repression

which of the following combinations will cause the rate of transcription to increase? a. a repressor plus an inducer b. a repressor plus a corepressor c. an activator plus an inhibitor d. none of the above will increase the rate of transcription

a. a repressor plus an inducer

The binding of __________ to the lac repressor causes the lac repressor to _________ to the operator site, thereby ________ transcription

allolactose, not bind, increasing

In the thi operon, when levels of TPP are low, the 5' end of the mRNA forms an __________ stem-loop structure that allows transcription to continue.

antiterminator

Transcription begins but terminates before the entire mRNA is made during ______

attenuation

regulatory proteins

bind to DNA and affect rate .....

The function of TFIID is to ______. bind to the core promoter and recruit RNA polymerase II to the TATA box bind to an enhancer to increase transcription from the core promoter bind to the TATA box and recruit RNA polymerase II to the core promoter prevent the binding of RNA polymerase II to the core promoter

bind to the TATA box and recruit RNA polymerase II to the core promoter

During attenuation, transcription begins, ______. but then a repressor protein binds to the operator and continues beyond the operon but it is terminated before the entire mRNA is made but translation stops after the eighth codon

but it is terminated before the entire mRNA is made

The CREB protein is a regulatory transcription factor that is activated following an increase in ______. cAMP glucocorticoid hormones RNA steroid hormones

cAMP

how does exposing an E coli cell to glucose affect the regulation of the lac operon via CAP?

cAMP does not bind to CAP and transcription is decreased

In feedback inhibition, the final product in a metabolic pathway ______. causes the formation of a stem-loop structure in the mRNA that prevents translation prevents translation of its own mRNA inhibits an enzyme that acts early in the pathway causes increased production of enzymes that act early in the pathway

causes increased production of enzymes that act early in the pathway

response to environmental stress

certain proteins help a bacterium survive an environmental stress, like osmotic shock or heat shock (only required when confronted with stress)

unregulated genes are also called _____

constitutive genes

Posttranslational regulation refers to ______. control of transcription initiation regulation of translation of mRNAs regulation of transcription termination control of proteins already in the cell

control of proteins already in the cell

Transcription factor proteins contain regions called ____ that specific functions

domains

what is a benefit of gene regulation?

efficient in terms of ENERGY USE (encoded proteins are produced only when they are required, cell avoids wasting valuable energy making proteins it doesn't need)

The binding of a regulatory transcription factor to a(n) ______________ can stimulate transcription 10- to 1000-fold, which is called ________ regulation.

enhancer, up

True or false: The rate of transcription initiation rarely influences overall gene expression. True false

false

When the product of a gene produced in a metabolic pathway inhibits an enzyme that acts early on in the pathway it is called

feedback initiation

Gene regulation means that ______. gene expression is controlled so that all genes in a genome are expressed at the same level gene expression can be controlled so that genes can be expressed at high or low levels only certain genes are included in the genome of a species

gene expression can be controlled so that genes can be expressed at high or low levels

The phenomenon in which the level of gene expression can vary under different conditions is:

gene regulation

In catabolite repression, transcription is influenced by the presence of _____. glucose lactose fructose galactose

glucose

what is an operon?

group of genes under the control of a single promoter

the most common way to regulate gene expression:

influence the rate at which transcription is initiated

which genes are under the control of the lac promoter?

lacZ, lacY, lacA genes

what is a more accurate way than saying genes being turned on/off

level of gene expression is increased/decreased

A translational repressor recognizes sequences within ______ and ______ translation. DNA; inhibits mRNA; increases mRNA; inhibits tRNA; increases rRNA; inhibits

mRNA, inhibits

If chromatin is in a closed conformation, nucleosome position and histone composition ______. make it easier for the DNA to become single stranded during transcription make it difficult for the DNA to become single stranded during transcription enhance the ability of transcription factors to gain access to and bind their target sequences in the promoter DNA make it difficult for transcription factors to gain access to and bind their target sequences in the promoter DNA

make it difficult for transcription factors to gain access to and bind their target sequences in the promoter DNA

3 common processes regulated at the genetic level

metabolism, response to environmental stress, cell division

____ can change in location along a DNA molecule, by replacement of a standard histone with a histone variant, and through covalent modifications on histone tails.

nucleosomes

gene regulation

phenomenon in which the level of gene expression can vary under different conditions

In the thi operon, when levels of TPP are low, the mRNA folds into a stem-loop structure that ______. prevents formation of the terminator stem-loop causes attenuation causes premature termination of transcription prevents the ribosome form binding to the start codon

prevents formation of the terminator stem-loop

cell division

some proteins are needed for cell division (necessary only when the cell is about to divide)

metabolism

some proteins function in the metabolism of small molecules, certain enzymes are needed for a bacterium to metabolize particular sugars (enzymes are only required when sugar is present in the environment)

Regulatory transcription factors that respond to steroid hormones are called:

steroid receptor

In bacteria, the most common way to regulate gene expression is by influencing ______. the frequency of cell division the rate of transcription elongation the rate of translation initiation the rate of transcription initiation

the rate of transcription initiation

why is it beneficial for the bacterium to regulate the lac operon with both a repressor protein and an activator protein?

the repressor protein allows the cell to avoid turning on the operon in absence of lactose. The activator protein allows the cell to choose between glucose and lactose

Riboswitches can regulate ______. transcription only posttranslational modification transcription or translation translation only

transcription or translation

A regulatory protein that inhibits translation is called a

translational repressor

Most histone genes encode standard histone proteins, but some have accumulated mutations that change the amino acid sequence of the histone proteins. These proteins are called histone ___

variants

The function of regulatory transcription factors must be modulated to ensure that genes are turned on ______. in growing cells only all the time under the appropriate environmental conditions in the correct cell type at the proper time

under the appropriate environmental conditions in the correct cell type at the proper time

what kind of genes have constant levels of expression?

unregulated genes (constitutive genes)

An enhancer is a DNA element that can be bound to a regulatory transcription factor, which leads to ______. transcriptional repression down regulation up regulation DNA replication

up regulation

What affect does acetylation have on lysines in core histone protein tails? Eliminates the negative charge on lysine, disrupting the electrostatic attraction between the histone and the positively charged DNA backbone Reason: The lysine side chain has a positive charge. Makes an additional negative charge on lysine, causing the DNA and the histone to repel one another Makes an additional positive charge on lysine, causing the DNA to bind more strongly to the histone Eliminates the positive charge on lysine, disrupting the electrostatic attraction between the histone and the negatively charged DNA backbone

Eliminates the positive charge on lysine, disrupting the electrostatic attraction between the histone and the negatively charged DNA backbone

The conversion of a riboswitch form one conformation to another is due to ______. a corepressor the covalent modification of the final product the binding of a small molecule the presence of CAP

the binding of a small molecule

under what condition is lac repressor bound to the lac operon?

the repressor protein is bound to the lac operon when allolactose is not bound to the repressor, which occurs when lactose is not available