Regulation of Gene Expression

Question 1

Access to promoters is restricted by

Answer 1

Chromatin structures

Question 2

What is positive and negative regulation?

Answer 2

Regulatory proteins, including transcription factors
(activators or repressors), are usually multimeric (different
polypeptides with different functions)

Question 3

What are enhancers?

Answer 3

DNA sites that bind activators and are distant
from the promoter
-activator binding can affect the rate of transcription at far
away promoters

Question 4

What are coactivators?

Answer 4

proteins that mediate the interaction between activators and RNA polymerase (protein repressors could bind at this place)

Question 5

What are architectural repressors?

Answer 5

proteins that bind to sites between a promoter and the activator or repressor binding site and facilitate DNA looping

Question 6

Regulatory proteins help in assembly of …………
with ……………………..
and ………………………

Answer 6

pre-initiation complex
HMG high mobility group: important for chromatin accessibility and transcription
UAS upstream activator sequence

Question 7

Repressor proteins interfere with …………………

Answer 7

communication between Pol II and the activators which leads to the inhibition of assembly or pre-initiation complex resulting in repression in transcription

Question 8

Eurochromatin

Answer 8

less condensed form of chromatin

Question 9

Heterochromatin

Answer 9

more condensed form of chromatin that is transcriptionally inactive

Question 10

Chromatin remodeling

Answer 10

transcription-associated strcutural changes in chromatin

Question 11

What does chromatin remodeling involve?

Answer 11

-repositioning nucleosomes
-the presence of histones variants
-covalent modification of nucleosomes

Question 12

What can modify chromatin structure?

Answer 12

-

Question 13

SWI/SNF complexes

Answer 13

remodel chromatin so that nucleosomes are ejected near transcription start sites
involved in a cycle that replaces nucleosomes with transcription factors

Question 14

Histone modifications

Answer 14

Modifications can be:
-methylation, phosphorylation, acetylation, ubiquitination and sumoylation

Question 15

Histone Acetylation

Answer 15

Reduction in interaction between histones and DNA by adding negative charged (reminder that DNA is charged)
Promote interaction with other proteins due to open chromatin:
-Histone acetyltransferases
-Histone deacetylases

Question 16

Histone Methylation interferes with ………………………. by ……………………………

Answer 16

chromatin configuration by changing conformation and interaction between histones, DNA and other proteins

Question 17

Is histone methylation related to increased or decreased transcriptional activity?

Answer 17

Both

Question 18

Typical Steroid Hormone Receptors

Answer 18

Steroids and vitamins
Covalent modifications (phosphorylation)

Question 19

How does DNA methylation modify chromatin structure?