Deck 32: The Control of Gene Expression in Eukaryotes

Question 1

When a steroid hormone receptor binds its ligand, it induces a conformational change in the ligand-binding domain which allows the binding of a(n) _______________.

Answer 1

coactivator

Question 2

Which of the following causes a decrease in transferrin receptor levels and an increase in ferritin levels?

A) magnesium
B) calcium
C) iron
D) potassium
E) manganese

Answer 2

C

Question 3

What is the complex of DNA and associated proteins in the eukaryotic cell?

A) chromosome
B) chromatid
C) chromatin
D) karyotype
E) None of the answers is correct.

Answer 3

C

Question 4

One of the classes of eukaryotic DNA-binding units is called bZip proteins because it has long α-helices stabilized by the amino acid __________________.

Question 5

What is the complex of protein subunits that acts as a bridge between transcription factors and RNA polymerase II?

A) coactivator
B) repressor
C) attenuator
D) mediator
E) None of the answers is correct.

Question 6

The technique ______________________ has been used to show that in eukaryotes, chromatin structure blocks a large number of potential protein binding sites.

Question 7

What enzyme has a role in repression of eukaryotic gene expression?

A) histone methylase
B) histone demethylase
C) histone acetylase
D) histone deacetylase
E) None of the answers is correct.

Question 8

A zinc finger domain is stabilized by a bound zinc ion through interactions with two __________ and two ______________ residues.

Question 9

Ferritin mRNA includes a 5′ stem-loop structure and binds a(n) _______________, which blocks the initiation of translation under low iron conditions.

Question 10

What eukaryotic DNA binding structure is similar to the prokaryotic helix-turn-helix?

A) helix-loop-helix
B) leucine zipper
C) zinc finger
D) winged helix-turn-helix
E) homeodomain fold

Question 11

What are proteins that act in a coordinated manner with hormone receptors to mediate gene expression?

A) coreceptors
B) cohormones
C) receptor-transcription mediators
D) cotranscription factors
E) coactivators

Question 12

The human genome contains genes for about _______________ proteins.

Question 13

The repeating unit formed by the DNA wrapping around the histone core is called a(n)_________________.

Question 14

Which of the following elements is found in the active site of the Argonaute-miRNA complex?

A) magnesium
B) calcium
C) zinc
D) iron
E) copper

Question 15

What are binding sites, present on DNA, that bind regulatory proteins, resulting in an increased level of transcription for a gene that is distant from the binding site?

A) promoter
B) enhancer
C) augmenter
D) amplifier
E) enlarger

Question 16

Seventy percent of the cytosines in human DNA are modified by methylation specifically in _______________ sequences.

Question 17

The existence of stable cell types is due to differences in _____.

A) the genome
B) the epigenome
C) histone acetylase activity
D) transposable elements
E) None of the answers is correct.

Question 18

What phenomenon allows for the generation of multiple distinct cell types?

A) combinatorial control
B) enhancer control
C) promoter control
D) epigenetic control
E) None of the answers is correct.

Question 19

The ______________ histone seals off the nucleosome at the location at which the linker DNA enters and leaves.

Question 20

DNA regions that serve as binding sites for transcription factors which can act at a distance to perturb the local chromatin structure are called _________________.

Question 21

How do coactivators mediate expression?

A) blocking RNA polymerase binding
B) modifying chromatin structure
C) inhibiting intron splicing
D) binding to enhancers
E) None of the answers is correct.

Question 22

Bromodomains are part of complexes which

A) bind proteins.
B) remodel chromatin.
C) alter ribosome binding.
D) remodel chromatin and alter ribosome binding.
E) All the answers are correct.

Question 23

Give examples of epigenomic changes resulting in different cell types.

Question 24

Structural components of the nucleosome include

A) transcription factors.
B) an octamer of core histones.
C) histone H8, which has an amino-terminal tail rich in leucine and isoleucine.
D) enhancer elements.
E) None of the answers is correct.

Question 25

What are significant features in the development of induced pluripotent stem cells?

A) Only four transcription factors are required to induce pluripotency in fibroblasts.
B) De-differentiated cells have characteristics of embryonic stem cells.
C) Potentially, iPS cells represent a new class of therapeutic agents.
D) All of the answers are correct.
E) None of the answers is correct.

Question 26

The interaction of many different protein factors to stimulate or repress transcription is called

A) combinatorial control.
B) synergy.
C) hypomethylation effect.
D) enhancer control.
E) None of the answers is correct.

Question 27

A key reaction in gene repression is the deacetylation of these amino acids in histones.

A) serine
B) threonine
C) arginine
D) lysine
E) All the answers are correct.

Question 28

What are the requirements for binding of the bromodomain to the transcriptional machinery?

Question 29

Enhancer sites are often located

A) near the poly(A) tail site.
B) within introns.
C) at a distance from the transcription start site.
D) immediately adjacent to the promoter.
E) None of the answers is correct.

Question 30

Histones

A) are basic.
B) constitute half the chromosome's mass.
C) serve to organize eukaryotic DNA.
D) All of the answers are correct.
E) None of the answers is correct.

Question 31

Regions that contain far more methylated cytosine than others are called

A) hypersensitive regions.
B) CpG islands.
C) TpG mutation sites.
D) hypermethylation regions.
E) None of the answers is correct.

Question 32

Although there are many differences between prokaryotic and eukaryotic gene expression, in what significant way due to the common structure of DNA are they similar?

Question 33

What is meant by combinatorial control of transcription in eukaryotes, and what is the advantage to this mechanism?

Question 34

Posttranscriptional eukaryotic gene expression can be controlled by

A) microRNAs.
B) histones.
C) basic-leucine zipper proteins.
D) helix-turn-helix proteins.
E) None of the answers is correct.

Question 35

Gene regulation by microRNAs involves

A) miRNA binding to Argonaute.
B) miRNA-Argonaute cleavage of mRNA.
C) miRNA-Argonaute binding to mRNA.
D) All the answers are correct.
E) None of the answers is correct.

Question 36

Molecules that bind to a receptor and trigger signaling pathways are called

A) antagonists.
B) agonists.
C) IRE-binding proteins.
D) promoters.
E) None of the answers is correct.

Question 37

Describe the arrangement of histones and associated DNA in a nucleosome.

Question 38

Which of the following are ways in which eukaryotic gene expression is more complex than prokaryotic gene expression?

A) different cell types that express only a subset of the genes in the genome
B) the lack of DNA binding proteins to direct gene expression
C) the inaccessibility of the DNA in chromatin
D) A and B are correct.
E) A and C are correct.

Question 39

In eukaryotes, DNA-binding proteins bind to DNA by which of the following DNA-binding structures?

A) Cys₂ His₂ zinc-finger domain
B) homeodomain
C) closed loops called lariats
D) Cys₂ His₂ zinc-finger domain and homeodomain
E) Cys₂ His₂ zinc-finger domain and closed loops called lariats

Question 40

Histone binding and wrapping of DNA reduces the DNA length by

A) 2-fold.
B) 7-fold.
C) 20-fold.
D) 100-fold.
E) 1000-fold.

Question 41

Describe the mechanism by which a steroid hormone receptor antagonist can function as a drug.

Question 42

How does a coactivator function in gene expression?

Question 43

What is a hypersensitive site in eukaryotic DNA?

Question 44

Describe the regulatory activity of microRNAs.

Question 45

Describe the functions of the two domains of a typical eukaryotic transcription factor.

Question 46

Why must gene regulation be more complicated in eukaryotic cells when compared to prokaryotic cells?

Question 47

Describe the structure and function of the histone octamer.

Question 48

Briefly describe the path of a steroid hormone in gene regulation.

Question 49

Describe how the IRE-binding protein regulates ferritin levels when iron levels are low.

Question 50

What is the function of mediator in regulating transcription?