Question 1

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

Accepted Answer

In eukaryotes, translational repression

Question 2

Which statement is TRUE of the attenuation mechanism used to regulate the tryptophan biosynthetic operon in E. coli?

Accepted Answer

A)  Attenuation is the only mechanism used to regulate the trp operon. 
B)  One of the enzymes in the Trp biosynthetic pathway binds to the mRNA and blocks translation when tryptophan levels are high. 
C)  The leader peptide plays a direct role in causing RNA polymerase to attenuate transcription. 
D)  Trp codons in the leader peptide gene allow the system to respond to tryptophan levels in the cell. 
E)  When tryptophan levels are low, the trp operon transcripts are attenuated (halted) before the operon's structural genes are transcribed. 
A)  Attenuation is the only mechanism used to regulate the trp operon. 
B)  One of the enzymes in the Trp biosynthetic pathway binds to the mRNA and blocks translation when tryptophan levels are high. 
C)  The leader peptide plays a direct role in causing RNA polymerase to attenuate transcription. 
D)  Trp codons in the leader peptide gene allow the system to respond to tryptophan levels in the cell. 
E)  When tryptophan levels are low, the trp operon transcripts are attenuated (halted) before the operon's structural genes are transcribed.

Question 3

"A protein with a gene that is actively being transcribed will be present in high concentrations." Why is this statement NOT true?

Accepted Answer

The statement "A protein with a gene tha

Question 4

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

Accepted Answer

Steroid hormones are a class of hormones

Question 5

Which factor 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 6

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 7

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

Basal transcription factors are essentia

Question 8

Which statement does NOT describe a reason why the major groove is more suited for sequence specificity interactions by DNA binding proteins?

Accepted Answer

A)  The methyl group of T residues is found in the major groove. 
B)  The major groove is larger, allowing more space for protein side chains. 
C)  The minor groove is negatively charged because of the crowding by phosphates. 
D)  Hydrogen bond donor and acceptor patterns are different in the major groove for different base pairs. 
E)  Two hydrogen bond acceptors exist for all base pairs in the minor groove. 
A)  The methyl group of T residues is found in the major groove. 
B)  The major groove is larger, allowing more space for protein side chains. 
C)  The minor groove is negatively charged because of the crowding by phosphates. 
D)  Hydrogen bond donor and acceptor patterns are different in the major groove for different base pairs. 
E)  Two hydrogen bond acceptors exist for all base pairs in the minor groove.

Question 9

_____ is a DNA sequence.

Accepted Answer

A)  Coactivator 
B)  Corepressor 
C)  Enhancer 
D)  Inducer 
E)  Transactivator 
A)  Coactivator 
B)  Corepressor 
C)  Enhancer 
D)  Inducer 
E)  Transactivator

Question 10

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 11

What is the functional complex that leads to proteolysis of LexA?

Accepted Answer

A)  RecA:dsDNA 
B)  LexA:dsDNA 
C)  RecA:ssDNA 
D)  LexA:ssDNA 
E)  LexA:RecA:ssDNA 
A)  RecA:dsDNA 
B)  LexA:dsDNA 
C)  RecA:ssDNA 
D)  LexA:ssDNA 
E)  LexA:RecA:ssDNA

Question 12

Name and contrast the four different types of stem cells found in humans.

Accepted Answer

There are four main types of stem cells

Question 13

The leader peptide below is from an E. coli biosynthetic operon. Which amino acid is MOST likely associated with this operon? MKRISTTITTTITITTGNGAG

Accepted Answer

A)  tyrosine 
B)  threonine 
C)  glycine 
D)  tryptophan 
E)  None of the answers is correct. 
A)  tyrosine 
B)  threonine 
C)  glycine 
D)  tryptophan 
E)  None of the answers is correct.

Question 14

"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 15

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 16

Small signal molecules that regulate transcription are NOT known to:

Accepted Answer

A)  cause activator proteins to bind DNA sites. 
B)  cause repressor proteins to bind DNA sites. 
C)  directly bind to DNA sites. 
D)  prevent activator proteins from binding to DNA sites. 
E)  release repressor proteins from DNA sites. 
A)  cause activator proteins to bind DNA sites. 
B)  cause repressor proteins to bind DNA sites. 
C)  directly bind to DNA sites. 
D)  prevent activator proteins from binding to DNA sites. 
E)  release repressor proteins from DNA sites.

Question 17

Define operon and polycistronic mRNA.

Accepted Answer

An operon is a functioning unit of genom

Question 18

Binding of uncharged tRNA in the ribosomal A-site

Accepted Answer

A)  1, 4, 2, 3 
B)  1, 4, 3, 2 
C)  4, 1, 2, 3 
D)  4, 1, 3, 2 
E)  4, 2, 1, 3 
A)  1, 4, 2, 3 
B)  1, 4, 3, 2 
C)  4, 1, 2, 3 
D)  4, 1, 3, 2 
E)  4, 2, 1, 3

Question 19

Which type(s) of proteins do(es) 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 20

The SOS response in E. coli is triggered by extensive damage to the cell's DNA and increases the capacity for repairing such DNA. What molecular events bring about expression of the SOS genes?

Accepted Answer

The expression of SOS genes in E. coli i

Exam 28: Regulation of Gene Expression

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

Which statement is TRUE of the attenuation mechanism used to regulate the tryptophan biosynthetic operon in E. coli?

"A protein with a gene that is actively being transcribed will be present in high concentrations." Why is this statement NOT true?

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

Which factor is NOT involved in steroid hormone action?

The operator region normally can be bound by:

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 statement does NOT describe a reason why the major groove is more suited for sequence specificity interactions by DNA binding proteins?

_____ is a DNA sequence.

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

What is the functional complex that leads to proteolysis of LexA?

Name and contrast the four different types of stem cells found in humans.

The leader peptide below is from an E. coli biosynthetic operon. Which amino acid is MOST likely associated with this operon? MKRISTTITTTITITTGNGAG

"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:

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?

Small signal molecules that regulate transcription are NOT known to:

Define operon and polycistronic mRNA.

Binding of uncharged tRNA in the ribosomal A-site

Which type(s) of proteins do(es) NOT interact with mediator?

The SOS response in E. coli is triggered by extensive damage to the cell's DNA and increases the capacity for repairing such DNA. What molecular events bring about expression of the SOS genes?

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

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

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

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Filters