Deck 21: Gene Expression: Transcription

Question 1

Change in the DNA-histone complex that increases transcriptional activity is termed

A) chromatin remodeling.
B) nucleosome formation.
C) induction.
D) gene regulation.
E) None of the above

Answer 1

A

Question 2

When a promoter element is bound by a positive regulatory protein, the result is

A) activation of replication.
B) activation of translation.
C) repression of transcription.
D) activation of transcription.
E) repression of replication.

Answer 2

D

Question 3

Proteins that are encoded by the same gene but differ in structure and function are the product of alternative splicing in pre-mRNA processing. Such protein variants are termed

A) isozymes.
B) isoteins.
C) allelomorphs.
D) protein isoforms.
E) heteromeric proteins.

Answer 3

D

Question 4

mRNAs synthesized in oocytes that are destined for storage and later translation have ________ poly(A) tails.

A) longer
B) no
C) two or more
D) shorter
E) None of the above

Question 5

Unlike prokaryotes, much gene regulation in eukaryotes

A) takes place at the transcriptional level.
B) is based on post-translational modification.
C) is controlled at the level of transcript processing.
D) is controlled by inhibitory proteins.
E) None of the above

Question 6

The protein cofactor ubiquitin is involved in

A) degradation of mRNA transcripts.
B) selective transport of mature mRNAs in the cytoplasm.
C) degradation of proteins.
D) differential splicing of pre-mRNA molecules.
E) construction of the cytoskeleton.

Question 7

Nucleosomes are

A) ribosome-mRNA complexes.
B) another term for centrioles.
C) condensed chromosomes.
D) Barr bodies.
E) DNA-histone complexes.

Question 8

Unlike bacterial operons, eukaryotic operons

A) are exceedingly rare.
B) are all negatively controlled.
C) are restricted to certain eukaryotic kingdoms.
D) are all positively controlled.
E) None of the above

Question 9

Chromosome-level gene repression involves

A) chromatin formation.
B) nucleosomes.
C) physical blockage of gene regions.
D) supercoiling.
E) all of the above.

Question 10

The half-life of a protein is directly related to

A) the number of stabilizing cross-linkages.
B) what kind of cell it is produced in.
C) its N-terminal amino acid residue.
D) its tertiary structure.
E) whether it is encoded by a constitutively expressed gene.

Question 11

Heterochromatin is associated with

A) heterozygotes.
B) mRNA translation.
C) gene silencing.
D) differential gene expression.
E) A, B, and C

Question 12

Which of the following secondary structures may be a DNA-binding domain?

A) Leucine zipper
B) Zinc finger
C) Helix-turn-helix
D) A, B, and C
E) A and B only

Question 13

5-methylcytosine is most often found associated with

A) polyadenylation.
B) the TATA box.
C) enhancer elements.
D) CG dinucleotides.
E) histones.

Question 14

The protein class(es) involved in the activation of transcription is (are):

A) coactivators.
B) transactivators.
C) general transcription factors (GTFs).
D) A and B
E) A, B, and C

Question 15

The influence of cell surface-binding hormones on gene expression is mediated by a process called

A) signaling.
B) adenyl cyclase.
C) messengering.
D) signal transduction.
E) All of the above

Question 16

Eukaryotic protein-coding genes contain both ________ elements and ________ elements.

A) promoter
B) enhancer
C) repressor
D) A and B
E) A, B, and C

Question 17

mRNA regulation can be achieved at the level of

A) transport.
B) translation.
C) processing.
D) life span (degradation).
E) All of the above

Question 18

In eukaryotic cells, receptors for steroid hormones are found in the

A) cytoplasm.
B) nucleus.
C) cell membrane.
D) A, B, and C
E) A and B only

Question 19

Hormones can be considered

A) inducers.
B) enzymes.
C) repressors.
D) transcription regulators.
E) translation regulators.

Question 20

Removal of the 5' G-cap of mRNA transcripts

A) reduces mRNA half-life.
B) leads to polyadelylation.
C) leads to degradation by exonucleases.
D) extends mRNA half-life.
E) prevents transcript transport.

Question 21

Eukaryotic repression generally occurs by physical blockage of the promoter.

Question 22

Embryonic development is orchestrated by a cascading series of genes, the expression of many of which are controlled in time and space by transcription factors and effector molecules of various kinds. But what controls the expression of the first regulatory genes to be transcribed in the newly fertilized zygote?

Question 23

Gene silencing is a form of regulation controlled by repressor proteins.

Question 24

Methylation, which in prokaryotes protects DNA from restriction, plays a role in gene silencing in eukaryotes.

Question 25

Interference RNA technology is one of the most exciting new developments in genetics in recent years. In April 2004, Cancer Research UK and the Netherlands Cancer Institute announced creation of a 24,000-molecule iRNA library, designed to inactivate about 8,000 human genes. One hope for this library is its application in combating cancer. How might iRNA be implemented in cancer treatment?

Question 26

Some genes that are expressed in the fetal stage are never expressed again in that individual's life. What do you think is the most common mechanism for affecting this, preventing the expression of such genes?

Question 27

Plants produce steroids called phytosterols, which have various functions in plant physiology. Some phytosterols are thought to have a defensive function, however, specifically in repelling insect herbivores. How might plant-derived steroids help protect plants from insect attack?

Question 28

In genetic imprinting, expression depends on the parent of origin of a given allele. How might imprinting affect the expression of a hypothetical autosomal disease that expresses in dominant fashion and recessive fashion, and how might imprinting be detected?

Question 29

Steriod hormones are effector molecules.

Question 30

Steroid and peptide hormone receptors are typically cytoplasmic.

Question 31

Explain how combinatorial gene regulation permits regulation of a large diversity of genes with relatively few regulatory proteins.

Question 32

Gene silencing in eukaryotes is often achieved through chromatin structure.

Question 33

Imprinting is thought to be implicated in Prader-Willi and Angelman's syndromes.

Question 34

Insect growth and metamorphosis is controlled by the steroid hormones ecdysone and juvenile hormone (JH). In insects like butterflies and moths with a distinct larval (juvenile) and adult stage, the relative amount of JH determines whether the insect molts to the next juvenile stage or switches to become an adult. Can you think of a way to use this hormonal system to control caterpillar agricultural pests?

Question 35

What is the essential difference between the growth and reproductive strategies of prokaryotes and multicellular eukaryotes that help us understand why the latter have far more sophisticated regulatory mechanisms?

Question 36

Describe the use of the DNA-degrading enzyme DNase I in experiments exploring the effect of chromatin on gene inactivation.

Question 37

What would happen developmentally if a zygote with XY sex chromosome karyotype had a defective testosterone receptor?

Question 38

Explain how the 3' untranslated AU-rich sequence element (ARE) can control poly(A) tail length (and thus mRNA translatability) in opposite ways.

Question 39

Transcriptionally active genes show lower levels of DNA methylation when compared to transcriptionally inactive genes.

Question 40

Recombinases mediate transcript processing from pre-mRNA to mature mRNA.

Question 41

What are some advantages and disadvantages of arranging gene clusters into operons?

Question 42

Several common protein structural motifs are now known to be involved in DNA recognition and binding. What are these, and how would researchers use genomic data to help figure out if new candidate genes encode such DNA-binding proteins?

Question 43

Evolutionary biologists suspect that genetic imprinting evolved through parent-offspring conflict. What kinds of "conflict of interest" in progeny development can you imagine between mammalian parents?