GENETICS Chapter 15 Flashcards

Structural motif

Enhancers

Strong purifying selection

Sonic hedgehog (SHH)

Insulator sequences

Chromatin packagin is caused by....

What do Covered promoters do?

What does Chromatin remodelers do?

What does Chromatin modifiers do?

DNA histone interactions are weak and regulatory sequences are accessible; transcription proceeds

DNA histone interactions are strong and regulatory sequences are not accessible; transcription is silent.

DNase I hypersensitivity

Methylated histones; Unmethylated histones

In negative control, what molecule would you expect to find bound to the operator if there is no transcription?

A) activator

B) repressor

C) inducer

D) corepressor

E) RNA polymerase

You want to design a repressor protein mutant. Which protein domain is the best target for preventing binding of the corepressor?

A) DNA-binding domain

B) allosteric domain

C) promoter domain

D) helix-turn-helix domain

E) activator binding site

The presence of which combination of molecules would lead to active transcription of an operon?

A) activator + corepressor

B) activator + repressor

C) inducer + corepressor

D) repressor + corepressor

E) activator + inducer

In the lac operon, what acts as the inducer?

A) glucose

B) permease

C) allolactose

D) β-galactosidase

E) transacetylase

The enzyme β-galactosidase catalyzes what reaction?

A) allolactose → glucose + lactose

B) lactose → glucose + fructose

C) lactose → galactose + glucose

D) glucose → galactose + lactose

E) galactose → glucose + lactose

A bacterium is unable to transport lactose into the cell to be broken down. Which gene is likely mutated in this bacterium?

A) lacZ

B) lacY

C) lacI

D) lacP

E) lacO

Which region of the lac operon would you target if you want to disrupt the -10 and -35 consensus sequences?

A) lacZ

B) lacY

C) lacI

D) lacP

E) lacO

In the presence of glucose, where is the lac repressor bound?

A) lacZ

B) lacO

C) lacP

D) lacI

E) The lac repressor is not bound to the operon.

Which structural gene of the lac operon can be mutated without affecting the cell's ability to break down lactose?

A) lacZ

B) lacY

C) lacA

D) lacP

E) lacO

Which of the following are constitutive mutants of the lac operon?

A) lacZ and lacP

B) lacZ and lacI

C) lacO and lacI

D) lacO and lacZ

E) lacI and lacY

Which mutants are noninducible?

A) lacIS

B) lacI-

C) lacI+

D) lacOC

E) lacO+

Which of these haploid strains produce β-galactosidase constitutively but do not produce permease?

A) I- P+ O+ Z+ Y+

B) I+ P+ O+ Z- Y-

C) I- P+ O+ Z-Y+

D) I+ P+ O- Z+ Y+

E) I- P+ O+ Z+ Y-

Which of these haploid strains produce permease but do not produce β-galactosidase?

A) I- P+ O+ Z+ Y+

B) I+ P+ O+ Z-Y+

C) I- P+ O+ Z-Y-

D) I+ P+ O- Z+ Y+

E) I- P+ O+ Z+ Y-

During the attenuation of the trp operon, which stem loop leads to polycistronic mRNA synthesis during tryptophan starvation?

A) 1-3 (antitermination) stem loop

B) 3-4 (termination) stem loop

C) 1-2 (pause) stem loop

D) 2-3 (antitermination) stem loop

E) 2-4 (termination) stem loop

In the absence of tryptophan,

A) the inactive repressor cannot bind trpO, so operon gene transcription occurs.

B) the active repressor binds trpP, so operon gene transcription is repressed.

C) the inducer cannot bind trpO, so operon gene transcription occurs.

D) the active repressor cannot bind trpO, so operon gene transcription is attenuated.

E) the repressor binds the corepressor, and operon gene transcription occurs.

Which sigma factor, encoded by the rpoH gene, is active at high temperatures?

A) σ70

B) σ32

C) σ45

D) σ37

E) σ50

Which enzyme is responsible for integration of a temperate phage into a host genome?

A) β-galactosidase

B) transposase

C) integrase

D) transacetylase

E) permease

Which region of the lambda phage genome enables the linear chromosome to circularize when it enters a host cell?

A) cohesive (cos) site

B) IS10

C) early operators

D) integrase (int) gene

E) excisionase (xis) gene

If you wanted to prevent a cell from entering the lysogenic pathway, which gene controlled by PRM would you target?

A) cro

B) Q

C) cI

D) cII

E) O

In λ phage, which protein, the product of the cI gene, blocks the transcription required to initiate the lytic cycle?

A) cro

B) repressor

C) enhancer

D) integrase

E) operator

Regulation of transcription of bacterial genes takes place at which two levels?

What are the two active sites or "domains" on a repressor protein?

If a corepressor is inhibited, what effect would you expect to see in the operon?

Which proteins facilitate RNA polymerase binding at promoters?

Catabolite repression refers to the repression of the lac operon in the presence of which catabolite?

Binding of which complex increases the ability of RNA polymerase to transcribe the lac operon?

Which enzyme is the product of the lacZ gene?

Which part of the lac operon is cis-dominant?

Which part of the lac operon produces a regulatory protein that is trans-acting?

In the absence of both glucose and lactose, the presence of which molecule is capable of inducing basal transcription?

Which protein in the arabinose operon is responsible for both positive and negative regulation of transcription?

In the trp operon, where is the attenuator region located?

Which molecule functions as the corepressor in the trp operon?

What are the three possible alternative stem loops that can form in mRNA?

Mutations of trpL decrease the efficiency of transcriptional regulation by disrupting the formation of which stem-loop structure?

Bacteria grown at 45°C initiate expression of which two types of proteins?

Antisense control of translation involves the regulation of which enzyme produced by bacterial insertion sequence IS10?

The genetic switch controlling whether a bacterium enters the lytic or lysogenic cycle relies on the binding of which two proteins?

What is the process by which a bacterium switches from a lysogenic to lytic cycle?

What protein cleaves the λ repressor monomers to inactivate the repressor protein, and is activated by DNA-damaging agents?

Most of the regulation of gene expression in bacteria occurs at the ________ level.

Changing conformation at the active site as a result of binding a substance at a different site is known as ________.

Expression of a(n) ________ alters gene transcription in E. coli by activating transcription of specialized heat stress response genes.

Bacterial translation is inhibited by ________ RNA, which is complementary to a portion of a specific mRNA.

In λ phage, entry into the ________ cycle requires transcription of late genes.