Question 1

Gene silencing by RNA interference acts by of the target gene.

Accepted Answer

A) inhibiting transcription 
B) inhibiting translation 
C) inhibiting splicing 
D) degradation of the mRNA 
E) inhibiting polyadenylyation 
A) inhibiting transcription 
B) inhibiting translation 
C) inhibiting splicing 
D) degradation of the mRNA 
E) inhibiting polyadenylyation

Question 2

Which of the following base pairs can form a hydrophobic interaction with a protein in the major groove?

Accepted Answer

A) A - T 
B) G - C 
C) T - A 
D) C - G 
E) Both A and C above 
A) A - T 
B) G - C 
C) T - A 
D) C - G 
E) Both A and C above

Question 3

Which one of the following does not contribute to the activation of transcription in eurkaryotes?

Accepted Answer

A) SWI/SNF chromatin remodeling proteins 
B) Histone acetyltransferases 
C) Histone methylases 
D) Histone deacetylases 
E) Alterations in histone content 
A) SWI/SNF chromatin remodeling proteins 
B) Histone acetyltransferases 
C) Histone methylases 
D) Histone deacetylases 
E) Alterations in histone content

Question 4

RecA protein provides the functional link between DNA damage and the SOS response by displacing the LexA protein from its operator sites on the SOS genes.RecA does so by:

Accepted Answer

A) associating with polymerase holoenzyme to help it remove LexA from operator. 
B) bending LexA operator DNA to force dissociation of LexA repressor. 
C) binding to LexA protein to weaken directly its affinity for operator sites. 
D) causing self-cleavage of LexA,thus inactivating its binding to operator. 
E) competitively binding to LexA operators and serving as an activator. 
A) associating with polymerase holoenzyme to help it remove LexA from operator. 
B) bending LexA operator DNA to force dissociation of LexA repressor. 
C) binding to LexA protein to weaken directly its affinity for operator sites. 
D) causing self-cleavage of LexA,thus inactivating its binding to operator. 
E) competitively binding to LexA operators and serving as an activator.

Question 5

Protein structural motifs often have general functions in common.Which one of the following motifs is known to be involved in protein dimer formation but not in direct protein-DNA interactions?

Accepted Answer

A) ($\beta$-barrel) 
B) Helix-turn-helix 
C) Homeodomain 
D) Leucine zipper 
E) Zinc finger 
A) ($\beta$-barrel) 
B) Helix-turn-helix 
C) Homeodomain 
D) Leucine zipper 
E) Zinc finger

Question 6

Which one of the following statements about eukaryotic versus prokaryotic gene regulation is not correct?

Accepted Answer

A) Access to eukaryotic promoters is restricted by the structure of chromatin. 
B) Most regulation is positive,involving activators rather than repressors. 
C) Larger and more multimeric proteins are involved in regulation of eukaryotic transcription. 
D) Transcription and translation are separated in both space and time. 
E) Strong promoters in eukaryotes are generally fully active in the absence of regulatory proteins. 
A) Access to eukaryotic promoters is restricted by the structure of chromatin. 
B) Most regulation is positive,involving activators rather than repressors. 
C) Larger and more multimeric proteins are involved in regulation of eukaryotic transcription. 
D) Transcription and translation are separated in both space and time. 
E) Strong promoters in eukaryotes are generally fully active in the absence of regulatory proteins.

Question 7

DNA-binding transactivating proteins often possess a domain separate from their DNA-binding domains that serves as a docking site for interactions with the transcription complex,coactivators,corepressors,or even chromatin remodeling proteins,to regulate gene transcription.Describe three known kinds of such domains,and provide an example of each.

Accepted Answer

(1)Gal4p (in yeast)has an acidic activat

Question 8

The DNA binding motif for many prokaryotic regulatory proteins,such as the lac repressor,is:

Accepted Answer

A) helix-turn-helix. 
B) homeobox. 
C) homeodomain. 
D) leucine zipper. 
E) zinc finger. 
A) helix-turn-helix. 
B) homeobox. 
C) homeodomain. 
D) leucine zipper. 
E) zinc finger.

Question 9

Transcription of the lactose operon in E.coli is stimulated by:

Accepted Answer

A) a mutation in the repressor gene that strengthens the affinity of the repressor for the operator. 
B) a mutation in the repressor gene that weakens the affinity of the repressor for the operator. 
C) a mutation in the repressor gene that weakens the affinity of the repressor for the inducer. 
D) binding of the repressor to the operator. 
E) the presence of glucose in the growth medium. 
A) a mutation in the repressor gene that strengthens the affinity of the repressor for the operator. 
B) a mutation in the repressor gene that weakens the affinity of the repressor for the operator. 
C) a mutation in the repressor gene that weakens the affinity of the repressor for the inducer. 
D) binding of the repressor to the operator. 
E) the presence of glucose in the growth medium.

Question 10

Describe briefly the process by which steroid hormones affect gene expression.

Accepted Answer

Steroid hormones usually enter a cell by

Question 11

Explain how synthesis of ribosomal proteins in E.coli is regulated at the level of translation.

Accepted Answer

Ribosomal proteins are encoded in severa

Question 12

Usually,a mutation in the promoter region of an operon causes reduced levels of synthesis of the proteins encoded by that operon.Occasionally,a mutation in the promoter region actually causes increased levels of synthesis.Can you suggest a plausible explanation?

Accepted Answer

It is possible for a mutation to result

Question 13

Large numbers of micro-RNAs (miRNAs),also known as small temporal RNAs (stRNAs),have now been discovered in higher eukaryotes.Describe their characteristics and general function.

Accepted Answer

Their primary transcripts are about 70 n

Question 14

Describe and contrast positive regulation and negative regulation of gene expression.

Accepted Answer

Positive regulation involves an activato

Question 15

Which one of the following does not interact with mediator?

Accepted Answer

A) TATA box 
B) TATA binding protein 
C) CTD of RNA polymerase 
D) TFIIH 
E) Modification and remodeling enzymes 
A) TATA box 
B) TATA binding protein 
C) CTD of RNA polymerase 
D) TFIIH 
E) Modification and remodeling enzymes

Question 16

A regulon is a(n):

Accepted Answer

A) group of related triplet codons. 
B) network of operons with a common regulator. 
C) operon that is subject to regulation. 
D) protein that regulates gene expression. 
E) ribosomal protein that regulates translation. 
A) group of related triplet codons. 
B) network of operons with a common regulator. 
C) operon that is subject to regulation. 
D) protein that regulates gene expression. 
E) ribosomal protein that regulates translation.

Question 17

Briefly explain 
(a)why there is a lag in cell growth when bacteria are switched from a medium containing glucose to one containing lactose.
(b)When the growth medium contains both lactose and glucose,what proteins will be bound to the lac operon regulatory region? 
(c)If only lactose is in the growth medium,what proteins will be bound to the lac operon regulatory region?

Accepted Answer

(a)The lag represents the time required

Exam 28: Regulation of Gene Expression

Gene silencing by RNA interference acts by of the target gene.

Which of the following base pairs can form a hydrophobic interaction with a protein in the major groove?

Which one of the following does not contribute to the activation of transcription in eurkaryotes?

RecA protein provides the functional link between DNA damage and the SOS response by displacing the LexA protein from its operator sites on the SOS genes.RecA does so by:

Protein structural motifs often have general functions in common.Which one of the following motifs is known to be involved in protein dimer formation but not in direct protein-DNA interactions?

Which one of the following statements about eukaryotic versus prokaryotic gene regulation is not correct?

The DNA binding motif for many prokaryotic regulatory proteins,such as the lac repressor,is:

Transcription of the lactose operon in E.coli is stimulated by:

Describe briefly the process by which steroid hormones affect gene expression.

Explain how synthesis of ribosomal proteins in E.coli is regulated at the level of translation.

Usually,a mutation in the promoter region of an operon causes reduced levels of synthesis of the proteins encoded by that operon.Occasionally,a mutation in the promoter region actually causes increased levels of synthesis.Can you suggest a plausible explanation?

Large numbers of micro-RNAs (miRNAs),also known as small temporal RNAs (stRNAs),have now been discovered in higher eukaryotes.Describe their characteristics and general function.

Describe and contrast positive regulation and negative regulation of gene expression.

Which one of the following does not interact with mediator?

A regulon is a(n):

The Foundations of Biochemistry

Water

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

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