Question 1

Describe briefly the relationship between chromatin structure and transcription in eukaryotes.

Accepted Answer

Heterochromatin is highly condensed and

Question 2

Protein amino acid side chains can hydrogen bond in the major groove of DNA,and discriminate between each of the four possible base pairs.In which one of the following groups of amino acids can all three members potentially be used in such DNA-protein recognition?

Accepted Answer

A) Ala,Asn,Glu 
B) Arg,Gln,Leu 
C) Asn,Gln,Trp 
D) Asn,Glu,Lys 
E) Glu,Lys,Pro 
A) Ala,Asn,Glu 
B) Arg,Gln,Leu 
C) Asn,Gln,Trp 
D) Asn,Glu,Lys 
E) Glu,Lys,Pro

Question 3

Consider the lac operon of E.coli.When there is neither glucose nor lactose in the growth medium:

Accepted Answer

A) CRP protein binds to the lac operator. 
B) CRP protein displaces the Lac repressor from the lac promoter. 
C) the repressor is bound to the lac operator. 
D) RNA polymerase binds the lac promoter and transcribes the lac operon. 
E) the operon is fully induced. 
A) CRP protein binds to the lac operator. 
B) CRP protein displaces the Lac repressor from the lac promoter. 
C) the repressor is bound to the lac operator. 
D) RNA polymerase binds the lac promoter and transcribes the lac operon. 
E) the operon is fully induced.

Question 4

Describe briefly the general role of the protein products of each of the following types of genes in the embryonic development of the Drosophila: 
(a)maternal genes
(b)segmentation genes
 (c)homeotic genes.

Accepted Answer

(a) A maternal gene in Drosophila is a g

Question 5

Match each of the operons with the type(s)of regulation present in that operon.Note that a given type can be used more than once,or not at all;also,a given operon may have more than one type of regulation.
-

Accepted Answer

(a)-(1,2)

Question 6

Which of the following is not true regarding the regulation of transcription in prokaryotes by RNA?

Accepted Answer

A) Small RNAs can disrupt local hairpins that prevent ribosome binding. 
B) Small RNAs require a protein chaperone to facilitate RNA-RNA base pairing. 
C) Riboswitches are often found in the 5-untranslated region of genes. 
D) Each riboswitch can bind an assortment of small metabolites. 
E) Riboswitches can affect either transcription of translation. 
A) Small RNAs can disrupt local hairpins that prevent ribosome binding. 
B) Small RNAs require a protein chaperone to facilitate RNA-RNA base pairing. 
C) Riboswitches are often found in the 5-untranslated region of genes. 
D) Each riboswitch can bind an assortment of small metabolites. 
E) Riboswitches can affect either transcription of translation.

Question 7

In prokaryotes such as E.coli,many operons that encode enzymes involved in amino acid biosynthesis begin with a sequence coding for a leader peptide.This peptide has no known enzymatic function and is rich in the amino acid that is synthesized by the enzymes coded for in the operon.What is the function of this leader peptide?

Accepted Answer

The leader peptide is integral to the re

Question 8

E.coli cells are placed in a growth medium containing lactose.Indicate how the following circumstances would affect the expression of the lactose operon (increase/decrease/no change).
(a)Addition of high levels of glucose
(b)A Lac repressor mutation that prevents dissociation of Lac repressor from the operator
(c)A mutation that inactivates $\beta$-galactosidase
(d)A mutation that inactivates galactoside permease
(e)A mutation that prevents binding of CRP to its binding site near the lac promoter

Accepted Answer

(a)decrease
(b)decrease
(c)decrease (thi

Question 9

Define operon and polycistronic mRNA.

Accepted Answer

An operon is several contiguous structur

Question 10

The operator region normally can be bound by:

Accepted Answer

A) attenuator. 
B) inducer. 
C) mRNA. 
D) repressor. 
E) suppressor tRNA. 
A) attenuator. 
B) inducer. 
C) mRNA. 
D) repressor. 
E) suppressor tRNA.

Question 11

The binding of CRP (cAMP receptor protein of E.coli)to DNA in the lac operon:

Accepted Answer

A) assists RNA polymerase binding to the lac promoter. 
B) is inhibited by a high level of cAMP. 
C) occurs in the lac repressor region. 
D) occurs only when glucose is present in the growth medium. 
E) prevents the repressor from binding to the lac operator. 
A) assists RNA polymerase binding to the lac promoter. 
B) is inhibited by a high level of cAMP. 
C) occurs in the lac repressor region. 
D) occurs only when glucose is present in the growth medium. 
E) prevents the repressor from binding to the lac operator.

Question 12

"Housekeeping genes" in bacteria are commonly expressed constitutively,but not all of these genes are expressed at the same level (the same number of molecules per cell).The primary mechanism responsible for variations in the level of constitutive enzymes from different genes is that:

Accepted Answer

A) all constitutive enzymes are synthesized at the same rate,but are not degraded equally. 
B) their promoters have different affinities for RNA polymerase holoenzyme. 
C) some constitutively expressed genes are more inducible than others. 
D) some constitutively expressed genes are more repressible than others. 
E) the same number of mRNA copies are made from each gene but are translated at different rates. 
A) all constitutive enzymes are synthesized at the same rate,but are not degraded equally. 
B) their promoters have different affinities for RNA polymerase holoenzyme. 
C) some constitutively expressed genes are more inducible than others. 
D) some constitutively expressed genes are more repressible than others. 
E) the same number of mRNA copies are made from each gene but are translated at different rates.

Question 13

The tryptophan operon of E.coli is repressed by tryptophan added to the growth medium.The tryptophan repressor probably:

Accepted Answer

A) binds to RNA polymerase when tryptophan is present. 
B) binds to the trp operator in the absence of tryptophan. 
C) binds to the trp operator in the presence of tryptophan. 
D) is a DNA sequence. 
E) is an attenuator. 
A) binds to RNA polymerase when tryptophan is present. 
B) binds to the trp operator in the absence of tryptophan. 
C) binds to the trp operator in the presence of tryptophan. 
D) is a DNA sequence. 
E) is an attenuator.

Question 14

Which of the following is false?

Accepted Answer

A) Unipotent cells can develop into only one type of cell or tissue. 
B) Pluripotent cells can develop into a complete organism. 
C) Multipotent bone marrow cells can develop into different types of blood cells. 
D) Totipotent cells can develop into any kind of tissue. 
E) Totipotent,unipotent,multipotent,and pluripotent are all types of stem cells. 
A) Unipotent cells can develop into only one type of cell or tissue. 
B) Pluripotent cells can develop into a complete organism. 
C) Multipotent bone marrow cells can develop into different types of blood cells. 
D) Totipotent cells can develop into any kind of tissue. 
E) Totipotent,unipotent,multipotent,and pluripotent are all types of stem cells.

Question 15

Which one of the following statements about the transcription attenuation mechanism is true?

Accepted Answer

A) In some operons (e.g. ,the his operon),attenuation may be the only regulatory mechanism. 
B) Sequences of the trp operon leader RNA resemble an operator. 
C) The leader peptide acts by a mechanism that is similar to that of a repressor protein. 
D) The leader peptide gene of the trp operon includes no Trp codons. 
E) The leader peptide is an enzyme that catalyzes transcription attenuation. 
A) In some operons (e.g. ,the his operon),attenuation may be the only regulatory mechanism. 
B) Sequences of the trp operon leader RNA resemble an operator. 
C) The leader peptide acts by a mechanism that is similar to that of a repressor protein. 
D) The leader peptide gene of the trp operon includes no Trp codons. 
E) The leader peptide is an enzyme that catalyzes transcription attenuation.

Question 16

Which one of the following is not involved in steroid hormone action?

Accepted Answer

A) Cell surface receptors 
B) Hormone-receptor complexes 
C) Specific DNA sequences 
D) Transcription activation and repression 
E) Zinc fingers 
A) Cell surface receptors 
B) Hormone-receptor complexes 
C) Specific DNA sequences 
D) Transcription activation and repression 
E) Zinc fingers

Question 17

Which of the following base pairs have a potential H-bond acceptor in both the major and minor grooves?

Accepted Answer

A) A - T 
B) G - C 
C) T - A 
D) C - G 
E) All of the above 
A) A - T 
B) G - C 
C) T - A 
D) C - G 
E) All of the above

Question 18

What are three mechanisms of translational repression that are known to exist in eukaryotes?

Accepted Answer

(a)Inactivation of initiation factors us

Question 19

Describe in one or two sentences the role of each of the following types of proteins in the regulation of gene expression in eukaryotes:  
(a) basal transcription factors
(b) transactivators
(c) coactivators.

Accepted Answer

(a)Basal transcription factors interact

Question 20

Which one of the following types of eukaryotic regulatory proteins interacts with enhancers?

Accepted Answer

A) Basal transcription factors 
B) Coactivators 
C) Repressors 
D) TATA-binding proteins 
E) Transactivators 
A) Basal transcription factors 
B) Coactivators 
C) Repressors 
D) TATA-binding proteins 
E) Transactivators

Exam 28: Regulation of Gene Expression

Describe briefly the relationship between chromatin structure and transcription in eukaryotes.

Protein amino acid side chains can hydrogen bond in the major groove of DNA,and discriminate between each of the four possible base pairs.In which one of the following groups of amino acids can all three members potentially be used in such DNA-protein recognition?

Consider the lac operon of E.coli.When there is neither glucose nor lactose in the growth medium:

Describe briefly the general role of the protein products of each of the following types of genes in the embryonic development of the Drosophila: (a)maternal genes (b)segmentation genes (c)homeotic genes.

Match each of the operons with the type(s)of regulation present in that operon.Note that a given type can be used more than once,or not at all;also,a given operon may have more than one type of regulation. -

Which of the following is not true regarding the regulation of transcription in prokaryotes by RNA?

Define operon and polycistronic mRNA.

The operator region normally can be bound by:

The binding of CRP (cAMP receptor protein of E.coli)to DNA in the lac operon:

"Housekeeping genes" in bacteria are commonly expressed constitutively,but not all of these genes are expressed at the same level (the same number of molecules per cell).The primary mechanism responsible for variations in the level of constitutive enzymes from different genes is that:

The tryptophan operon of E.coli is repressed by tryptophan added to the growth medium.The tryptophan repressor probably:

Which of the following is false?

Which one of the following statements about the transcription attenuation mechanism is true?

Which one of the following is not involved in steroid hormone action?

Which of the following base pairs have a potential H-bond acceptor in both the major and minor grooves?

What are three mechanisms of translational repression that are known to exist in eukaryotes?

Describe in one or two sentences the role of each of the following types of proteins in the regulation of gene expression in eukaryotes: (a) basal transcription factors (b) transactivators (c) coactivators.

Which one of the following types of eukaryotic regulatory proteins interacts with enhancers?

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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