Chapter 18

Question 1

Why regulate gene expression?

Answer 1

Able to respond to environment

Question 2

How do bacteria respond to environmental change?

Answer 2

Regulate transcription

Produce only what they need

Question 3

Operator

Answer 3

On-off switch

Question 4

Operon

Answer 4

Entire stretch of DNA that includes the operator, promoter, and genes they control

Question 5

Repressor

Answer 5

Protein that switches OFF the operon

Bind to operator to block RNA polymerase

STOP polymerase

Activate the operator

Question 6

What is the repressor a product of?

Answer 6

The regulatory gene

Question 7

Corepressor

Answer 7

Molecule that cooperates with a repressor protein to switch an operon off

Question 8

trp uses a…

Answer 8

repressor

so, when lots of trp is present the polymerase will be stopped

Question 9

Repressible operon

Answer 9

Usually on

Needs REPRESSOR to shut off (stop producing gene)

trp

Question 10

Inducible operon

Answer 10

Usually off

Needs INDUCER to turn on (start producing gene)

lac

Question 11

Inducers

Answer 11

Inducers remove repressors so the gene gets shut off

Question 12

Differential gene expression

Answer 12

the expression of different genes by cells with the same genome

Question 13

Histone acetylation

Answer 13

Loosens chromatins

Makes them more expressed

short term

only eukaryotes

Question 14

Histone methylation

Answer 14

Coils chromatins

Makes them less expressed

Long term

only eukaryotes

Question 15

Epigentic inhertance

Answer 15

DNA sequence not changed

Traits expressed due to acetylation and metyhlation

Only eukaryotes

Question 16

Control elements

Answer 16

Segments of noncoding DNA that serve as binding sites for transcription factors

Question 17

Enhancers

Answer 17

distal control elements

far away from promoter

Question 18

TATA Box

Answer 18

Proximal control element

close to promoter

Question 19

Activator

Answer 19

Protein that binds to an enhancer and stimulates transcription of a gene

Question 20

Mediator proteins

Answer 20

Grape like thing that folds the protein once activators are attatched to dismal enhancers

Question 21

Combinatorial Control of Gene Activity

Answer 21

Particular combination of control elements can activate transcription only where appropriate activator proteins are present

Question 22

Alternative RNA splicing

Answer 22

Allows many types of proteins from one gene

Question 23

Repressible operons products

Answer 23

The product of the genes also turns the genes off

Regulatory

Makes repressors to shut itself off

Question 24

Mutation to the regulatory genes that make repressors not work?

Answer 24

Gene always on

Question 25

What would happen if you couldn’t bind lactose (lac) to a repressor?

Answer 25

The gene would always be off

If you block the inducer, the repressor would never be removed

Question 26

What happens when you move the operator?

Answer 26

Whatever is before it is no longer expressed

Question 27

Where do general transcription factors bind?

Answer 27

TATA box

Enhancers

Question 28

What is the only thing prokaryotes can do?

Answer 28

Regulate when to turn of or turn off genes

Question 29

How do you coordinate expression of genes?

Answer 29

Share single common enhancer

Question 30

The tryptophan operon is a repressible operon that is

Answer 30

turned off when tryptophan is added

Question 31

What protein is produced by a regulatory gene?

Answer 31

repressor

Question 32

Lack of corepressor?

Answer 32

Genes are always going to be turned on

Question 33

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

Answer 33

continuous transcription of the structural gene controlled by that regulator.

Question 34

The lactose operon is likely to be transcribed when

Answer 34

the cyclic AMP and lactose levels are both high within the cell.

Question 35

Transcription of the structural genes in an inducible operon

Answer 35

starts when the pathway’s substrate is present

Question 36

For a repressible operon to be transcribed, which of the following must occur?

Answer 36

RNA polymerase must bind to the promoter, and the repressor must be inactiv

Question 37

In response to chemical signals, prokaryotes can do which of the following?

Answer 37

alter the level of production of various enzymes

Question 38

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant?

Answer 38

It cannot bind to the inducer.

Question 39

Which of the following mechanisms is (are) used to coordinate the expression of multiple, related genes in eukaryotic cells?

Answer 39

Genes are organized into clusters, with local chromatin structures influencing the expression of all the genes at once.

Question 40

If you were to observe the activity of methylated DNA, you would expect it to

Answer 40

have turned off or slowed down the process of transcription.

Question 41

Which processes contribute to this dynamic activity?

Answer 41

methylation and phosphorylation of histone tails

Question 42

Two potential devices that eukaryotic cells use to regulate transcription are

Answer 42

DNA methylation and histone modification.

Question 43

Steriod hormones bind to

Answer 43

Intracellular receptors

Question 44

Transcription factors in eukaryotes usually have DNA binding domains as well as other domains that are also specific for binding. In general, which of the following would you expect many of them to be able to bind?

Answer 44

other transcription factors

Question 45

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?

Answer 45

exons alternative splicing