Genetics Exam 3 Review Ch. 14

________ and ________ regulate whether RNA transcription takes place.

Activators repressors

When there is a _____ tryptophan level, the leader region is translated _____ by a ribosome, which then causes the formation of stem and loop of the mRNA which results in the _______ of transcription

HIGH completely termination

When there is a _____ tryptophan level, the ribosome is _______ at trp codons, which then causes transcription to _______

LOW stalled continued

_______ control of transcription involves the binding of an activator protein to the activator-binding site of a regulatory DNA, with the result of __________ gene transcription

Positive initiating

lacA gene codes for the enzyme ________ which protects against harmful by-products of lactose metabolism

Transacetylase

When there is tryptophan ______, there is termination of transcription due to the fact that the ribosome completes translation of trpL coding sequence and occupies regions 1 and 2, which then causes region _ and _ which then causes transcription termination

abundance 3 4

High Glucose indirectly inhibits an _______ that binds to the promoter of the lac operon

activator

When lactose available and glucose is unavailable and with repressor protein inactivated by ________ binding, RNA polymerase carries out transcription

allolactose

The trp leader peptide sequence contains an _______ region that reduces the transcription and two tryptophan codons

attenuator

Which of the following conditions will result in the greatest levels of transcription of the lac operon? a)Lactose present, cAMP and glucose absent b)Lactose and cAMP present, glucose absent c)Lactose and glucose present, cAMP absent d)Lactose, glucose, and cAMP present

b) Lactose and cAMP present, glucose absent The inducer lactose inactivates the lac repressor and cAMP activates CAP. The combination of inactive repressor and active CAP results in the highest level of transcription of the lac operon.

If glucose is present and lactose , cAMP, and allolactose is absent then lac Operon transcription is ______ due to the fact that glucose is present to provide energy

basal

If glucose, lactose, and allolactose is present and cAMP is absent then lac Operon transcription is ______ due to the fact that glucose is present to provide energy and the absence of cAMP _____ positive transcription regulation

basal positive

If glucose and lactose are absent and cAMP and allolactose are absent then lac Operon transcription is ______ due to the fact that the CAP-cAMP forms, but no inducer is present to block the ______ from binding at the operator

basal repressor

When bacteria are in an environment that contains Lactose, they produce the enzyme ____-_________ which allows the breakdown of Lactose into two sugars that the bacterium can use.

beta-Galactosidase

lacZ gene codes for the enzyme ___-_______ enzyme that cleaves lactose into 2 monosaccharides (glucose and _______)

beta-galactosidase galactose

Binding of repressor protein ______ transcription by _____ regulation

blocks negative

When _______ is absent, repressor does not bind thus _______ transcription

corepressor

Binding of repressor-_______ complex blocks transcription by _____ regulation

corepressor negative

Which molecule serves as the inducer for the lac operon? a)cAMP b)Glucose c)Galactose d)Lactose

d) Lactose Lactose inactivates the lac repressor, which allows transcription of the lac operon to occur.

Also the bacterial lac operon does not want to make the beta-Galactosidase enzyme when ______ is present

glucose

_______ is the preferred energy source of bacteria

glucose

_______ levels control the lac operon

glucose

In the lac system, the repression of the lac operon is by the presence of ______ because it ______ an activator

glucose inhibits

If glucose is absent and lactose , cAMP, and allolactose is present then lac Operon transcription is ______ due to the fact that the inducer and CAP-cAMP available to induce and positively regulate transcription

high

glucose levels regulate camp levels: when there is _____ glucose levels, ATP cannot convert to cAMP

high

With I+ wild type gene, the repressor binds to the operator when the inducer is absent and forms an ______-_______ when inducer is present

inducer repressor

The unit consisting of the lac promoter, lac operator and the lacZ, lacY, and lacA genes is called the ____ _______.

lac operon

LacI encodes the ___ ________ protein; it is ________ expressed

lac repressor constitutively

______ structural gene which encodes transacetylase

lacA

lac repressor protein binds to the operator (____) sequence and _______ transcription

lacO inhibits

____ structural gene which encodes the enzyme permease

lacY

____ structural gene encodes β-galactosidase

lacZ

____ and ____ are needed for β-Gal activity

lacZ lacY

The three structural genes are _____, _____,and ____.

lacZ lacY lacA

The ____ gene is next to, but not part of, the lac operon

lacl

In the lac system, the lac operon is transcribed only in the presence of _____ because it binds to the repressor and inactivates it

lactose

The lac operon is transcribed only in the presence of ____

lactose

glucose levels regulate camp levels: when there is _____ glucose levels, ATP is able to convert to cAMP

low

_______ control of transcription involves binding of a repressor protein to the operator of a regulatory DNA sequence, with the consequence of __________ transcription of a gene or a cluster of genes

negative preventing

lacO encodes the ______ sequence that binds repressor proteins to block transcription of the operon genes

operator

When there is no lactose, the repressor sits on the ______ and _____ transcription

operator blocks

In bacteria, the place where repressors bind are termed ________.

operators

With the O^c (operator constitutive mutation), the ______-site mutation prevents repressor protein binding and leads to constituitive synthesis of the lac operon

operon

lacY gene codes for the enzyme ______ which facilitates ______ transport across the cell membrane

permease lactose

The lacZ, lacY, and lacA structural genes are transcribed as a single, ________ mRNA, which is translated to produce the three distinct polypeptides

polycistronic

With the I- (repressor mutation), the repressor protein mutation ______ repressor binding to the operator and produces constitutive synthesis of the lac operon

prevents constitutive

The _______ region is where RNA polymerase binds and transcription starts.

promoter

lacP is the ______ sequence that binds the RNA polymerase and is needed to transcribe ___, ___, and ____ as a single polycistronic mRNA

promotor lacZ lacY lacA

Mutations _____ complementarity

reduce

Abundant tryptophan _____ transcription of the trp operon

reduces

They don't want to "waste" energy by making the enzyme beta-Galactosidase all the time, so its gene needs to stay _______ until Lactose is present

repressed

Glucose _______ the lac operon

represses

Binding of inducer molecule to _______ protein allows transcription

repressor

Glucose present (cAMP low); no lactose ; no lac mRNA causes the ______ to bind thus causing there to be no transcription

repressor

I gene: makes the _______ (constitutively - always on)

repressor

a _______ in a lac operon prevents mRNA from being transcribed

repressor

lacL gene produces a _______ protein that contains 2 finding sites, one for the ______ and one for the lactose which is the ______.

repressor operator inducer

When there is tryptophan ______, there is antitermination of transcription due to the fact that the ribosome stalls at region _ and regions _ and _ pair with then causes transcription to continue into operon genes

starvation 1 2 3

The cAMP-CAP complex activates ______ by binding to the _______ region of the lac operon and activating it

transcription promoter