Deck 14: Networks of Gene Regulation

Question 1

Which of the following is the critical regulatory stage for the majority of genes?

A) mRNA transport
B) mRNA splicing
C) Initiation of translation
D) Initiation of transcription
E) Polypeptide modification

Answer 1

Initiation of transcription

Question 2

An ______ consists of multiple genes that are transcribed as a single transcript

Answer 2

operon
Explanation: An operon consists of multiple genes that are transcribed as a single transcript. All the genes in an operon are therefore subject to the same transcriptional regulation.

Question 3

Where do repressor proteins bind?

A) Repressor sequence
B) Activator sequence
C) 3' UTR
D) Operator sequence

Answer 3

Operator sequence

Question 4

Match the missing words in the following phrase. Tryptophan is an essential amino acid. Wild-type E. coli can synthesize their own tryptophan and are called [A]. Mutants that cannot synthesize an essential nutrient like tryptophan are called [B]. Transcription of the genes for tryptophan synthesis is not [C]: i.e., the genes are transcribed only when needed. Transcription is therefore [D]. When tryptophan is [E], the repressor [F] and transcription of the tryptophan mRNA proceeds. When tryptophan is [G], the repressor [H] and transcription is prevented.

Question 5

Tryptophan is involved in transcriptional regulation of the tryptophan-encoding genes. It does this by binding to the tryptophan repressor. Tryptophan is therefore a ________

Question 6

Attenuation is involved in the regulation of tryptophan production in E. coli. Which factors are involved in the tryptophan attenuation mechanism?

A) Hairpin formation
B) Transcription termination
C) Translation
D) Transcription initiation
E) Repression

Question 7

Match the points on the bacterial growth curve with their descriptions.


-No cell division

A) A
B) B
C) C
D) D

Question 8

Match the points on the bacterial growth curve with their descriptions.


-Cells doubling at steady rate

A) A
B) B
C) C
D) D

Question 9

Match the points on the bacterial growth curve with their descriptions.


-Nutrients exhausted

A) A
B) B
C) C
D) D

Question 10

Match the points on the bacterial growth curve with their descriptions.


-Cell death exceeds cell division

A) A
B) B
C) C
D) D

Question 11

Fill in the blank. The biochemical process of breaking down a complex molecule into its simpler components is termed _____

Question 12

A growth curve is shown for E. coli cultivated in media containing lactose and glucose. At which points on the growth curve is the lac operon transcribed? Please select all that apply.

A) A
B) B
C) C

Question 13

In the regulatory system that controls the lac operon, which molecule directly reflects the level of glucose in the cell?

A) cAMP
B) CAP
C) Lac repressor
D) lactose

Question 14

Which of the following statements about the lac repressor is true?

A) The lac repressor is encoded by the lacI gene, which is located within the lac operon
B) The lac repressor is encoded by the lacZ gene, which is located within the lac operon
C) The lac repressor is encoded by the lacZ gene, which is located outside the lac operon
D) The lac repressor is encoded by the lacI gene, which is located outside the lac operon

Question 15

Which of the following statements about the lac and trp operons in E. coli are true? Please select all that apply.

A) The lac operon is turned on in the presence of lactose.
B) The trp operon is turned on in the presence of tryptophan
C) The lac repressor and the trp repressor both bind to the operator for their respective operons.
D) Tryptophan is used as a carbon source in the presence of glucose
E) Lactose is used as a carbon source in the presence of glucose.

Question 16

Match the protein binding patterns at the lac operon with the appropriate transcriptional outcomes.

-CAP and lac repressor bound to DNA

A) Lac operon is not transcribed
B) Lac operon is weakly transcribed
C) Lac operon is strongly transcribed

Question 17

Match the protein binding patterns at the lac operon with the appropriate transcriptional outcomes.

-Neither CAP nor lac repressor bound to DNA

A) Lac operon is not transcribed
B) Lac operon is weakly transcribed
C) Lac operon is strongly transcribed

Question 18

Match the protein binding patterns at the lac operon with the appropriate transcriptional outcomes.

-CAP bound to DNA, lac repressor not bound to DNA

A) Lac operon is not transcribed
B) Lac operon is weakly transcribed
C) Lac operon is strongly transcribed

Question 19

What is a regulon?

A) A regulatory sequence associated with an operon
B) One gene within an operon
C) Regulon is another term for operon
D) The set of genes controlled by an activator

Question 20

Operons are a key mechanism for co-regulation of genes in bacteria and eukaryotes.

Question 21

Which of the following statements about polar mutations are true? Please select all that apply.

A) A polar mutation is a mutation in one gene that decreases expression of an upstream gene
B) Polar mutations usually increase the distance between two genes in an operon
C) Mutations in the last gene in an operon are not usually polar
D) Polar mutations can usually be rescued by supplying a wild-type version of a gene on a plasmid

Question 22

Which of the following techniques is used to compare the expression profiles of cells under different conditions?

A) One-channel microarray
B) Two-channel microarray
C) ChIP
D) RNA-Seq

Question 23

Eukaryotic genes are controlled by more than one transcription factor, but each transcription factor is only involved in the transcription of one gene.

Question 24

Why is it difficult to accurately identify transcription factor binding sites by scanning the genome sequence? Please select all that apply.

A) Transcription factor binding sites are variable
B) Transcription factors bind to RNA, not DNA
C) The distance between the transcription start site and the transcription factor binding site is variable
D) Transcription factor binding sites are usually long

Question 25

In ChIP, what sort of molecule is used to isolate chromatin attached to the transcription factor of interest

A) Carbohydrate
B) DNA
C) RNA
D) Protein

Question 26

Put the following steps in a ChIP experiment in order, beginning with the first

-Cross-link DNA and proteins

A) 1 (first)
B) 2
C) 3
D) 4

Question 27

Put the following steps in a ChIP experiment in order, beginning with the first

-Fragment chromatin

A) 1 (first)
B) 2
C) 3
D) 4

Question 28

Put the following steps in a ChIP experiment in order, beginning with the first

-Precipitate chromatin attached to transcription factor of interest

A) 1 (first)
B) 2
C) 3
D) 4

Question 29

Put the following steps in a ChIP experiment in order, beginning with the first

-Sequence DNA

A) 1 (first)
B) 2
C) 3
D) 4

Question 30

Which of the following are limitations of ChIP experiments? Please select all that apply.

A) ChIP requires use of microarrays
B) ChIP can only indirectly predict where transcription factors bind.
C) Transcription factors must be examined one at a time.
D) ChIP does not provide information about dynamic changes in a cell

Question 31

Which of the statements about the transcription factors illustrated in the network diagram are true? Please select all that apply.

A) LIN-39 regulates four transcription factors
B) LIN-39 is regulated by two transcription factors
C) MAB-5 is regulated by one transcription factor
D) EGL-27 does not regulate any transcription factors
E) MAB-5 regulates LIN-39

Question 32

Fill in the blank. Many transcription factors target their own gene for regulation. This is termed ________________

Question 33

Match the missing words in the following phrase. Different biological processes are governed by different types of regulatory networks that often reflect the type of regulation needed. For example, the stress response in yeast is very [A] and involves a small number of transcription factors activating [B] genes. For very [C] processes such as the cell cycle, many transcription factors are involved in regulating [D] genes. Transcription networks are hierarchical, with [E] controlling large networks; these are in turn coordinated by [F].