Chapter 17: Control of Gene Expression in Eukaryotes Flashcards Preview

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Flashcards in Chapter 17: Control of Gene Expression in Eukaryotes Deck (134)
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1

What are transcription factors?

Regulatory proteins that bind to specific DNA sequences

Transcription factors are proteins that bind to specific DNA recognition sequences in the promoter or enhancer elements of a gene.

2

Which of the following elements is not a DNA binding domain?

Leucine zipper
Zinc finger
Helix-turn-helix
Gal4p

Gal4p

Gal4p is a yeast protein that contains a DNA binding domain.

3

True or False?

Alternative splicing is an example of gene regulation that occurs after the synthesis of mRNA.

True

Alternative splicing is a form of mRNA processing and occurs after mRNA synthesis.

4

True or False?

Transcription and translation are not coupled in eukaryotic cells, although both processes take place in the cytoplasm.

False

In eukaryotes, transcription and translation are not coupled because transcription occurs in the nucleus and translation in the cytoplasm.

5

True or False?

In general, one could say that fewer levels of regulation are possible in prokaryotes than in eukaryotes.

True

6

How does DNA methylation regulate gene activity?

by adding methyl groups to the cytosine of CG doublets in DNA

Methylation of 5-methyl-CpG DNA sequences appears to inactivate transcription of the sequences.

7

Which process seems to be the most similar between eukaryotic and prokaryotic genetic regulation?

transcriptional regulation

8

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation refers to ________.

addition of methyl groups to the cytosine of CG doublets

9

Which of the following elements function specifically in eukaryotic transcription and gene expression?

promoters and enhancers

Promoters are the sites of assembly of the basic transcription complex, and along with enhancers, control transcription in eukaryotes.

10

Which of the following clusters of terms applies when addressing enhancers or silencers as elements associated with eukaryotic genetic regulation?

cis-acting, variable orientation, variable position

11

Mutations in the promoter region of the β-globin gene indicate that some areas are more sensitive than others. When mutations occur in consensus sequences (modular elements such as GC box, CAAT box, TATA box), does transcription usually increase or decrease?

decrease

12

True or False?

Transcription in eukaryotes is generally influenced by enhancers just as in prokaryotes.

False

13

Which of the following best describes the mechanism by which steroid hormones control gene expression?

Steroid hormones that enter the cell activate receptors. These hormone-receptor complexes then bind HREs and influence gene expression.

14

The reason some cells respond to the presence of a steroid hormone while others do not is that _______.

the receptors necessary for regulation differ among cells of various types

The specificity of steroid hormone regulation is due to the presence or absence of the receptor in different cell types.

15

Which of the following best describes the role of chaperone proteins in the regulation of gene expression by steroid hormones?

Chaperone proteins maintain functionality of the receptor.

Chaperone proteins maintain the functionality of the receptor prior to binding of the steroid hormone to the receptor.

16

What are transcription factors?

regulatory proteins that bind to specific DNA sequences

Transcription factors are proteins that bind to specific DNA recognition sequences in the promoter or enhancer elements of a gene.

17

Which of the following statements about transcription factors is true?

Transcription factors bind DNA sequences present in the enhancer and activate transcription via protein-protein interactions with RNA polymerase.

Transcription factors carry out two functions: they bind to DNA sequences in the enhancer, and they activate transcription via their interactions with RNA polymerase.

18

When transcription factors interact with DNA, is the resulting genetic control typically positive or negative?

positive

19

Transcription factors are proteins with at least two functional domains–one that binds to DNA and one that binds to RNA polymerase or to other transcription factors.

True

20

What is the function of an activator?

It physically makes contact with some element of the transcription complex and activates transcription.

Activators stimulate transcription by RNA polymerase II.

21

In the galactose utilization system of yeast, the GAL4 protein is a(n) ______.

activator

GAL4 contains a transcription-activating domain, which, when exposed, activates transcription of GAL7, GAL10, and GAL1.

22

In what way do upstream activator sequences (UASs), regulatory sequences in yeast, differ from enhancers and silencers?

UASs function only upstream.

23

Which processes are examples of posttranscriptional regulation in eukaryotes?

alternative splicing of single mRNA transcripts to give rise to multiple mRNAs and increased stability of the mRNA

Alternative splicing of mRNA transcripts and increased mRNA stability are two processes used to regulate gene expression posttranscriptionally.

24

True or False?

Alternative RNA processing can result in different mRNAs that start with different exons.

True

25

True or False?

The term spliceopathy is often used to signify a genetic condition caused by a defect in the regulation of RNA splicing.

True

26

What is the role of Dicer in RNA-induced gene silencing?

cleaves longer RNAs into short, regulatory RNA molecules

The regulatory siRNAs and miRNAs are involved in suppression of gene expression.

27

Many promoter regions contain CAAT boxes containing consensus sequences CAAT or CCAAT approximately 70 to 80 bases upstream from the transcription start site.

How might one determine the influence of CAAT boxes on the transcription rate of a given gene?

Delete the CAAT box sequence and measure the transcription rate.

Make mutations in the CAAT box sequence and measure the transcription rate.

Introduce extra CAAT box sequences and measure the transcription rate.

28

A deletion within the GAL4 gene that removes the region encoding amino acids 1 to 100.

A deletion within the GAL4 gene that removes amino acids 1-100 would remove the DNA-binding section and not allow transcriptional activation.

29

A deletion of the entire GAL3 gene.

Without the product of the GAL3 gene, there would be no disruption of the Gal4p/Gal80p complex and therefore no transcription of the GAL1 gene.

30

A mutation within the GAL80 gene that blocks the ability of Gal80 protein to interact with Gal3p.

If the GAL80 gene product can’t interact with Gal3p, there can be no interaction with the Gal4p/Gal80p complex and therefore no GAL1 transcription.