Regulation of Gene Expression

Question 1

What is induction?

Answer 1

causing gene product concentration to increase

Question 2

What is repression?

Answer 2

causing gene product concentration to decrease

Question 3

What is a housekeeping gene?

Answer 3

Expressed all the time, needed for survival

Question 4

What is a regulated gene?

Answer 4

Only expressed when needed

Question 5

Where are regulatory proteins located?

Answer 5

On the right, downstream

Question 6

Where are promotors located?

Answer 6

On the left, upstream

Question 7

RNA is synthesizes in which direction?

Answer 7

5’-3’

Question 8

Negative Regulation controls the:

Answer 8

Repressor

Question 9

Positive regulation controls the:

Answer 9

Activator

Question 10

In eukaryotes, what type of gene regulation is most common?

Answer 10

Positive

Question 11

The promoter has a repressor binding site in which types of organisms?

Answer 11

Prokayotes

Question 12

Which amino acids commonly interact with nucleic acids?

Answer 12

Asn, gln, Glu, Lys, Arg

Question 13

What are the 3 types of DNA binding motifs?

Answer 13

1. Helix turn Helix
2. Zn finger
3. Leu Zipper

Question 14

How many recognition helices are there in the Helix turn Helix?

Answer 14

1-usually contains many of the AA’s that interact with DNA

Question 15

Zn fingers and in which type of organisms?

Answer 15

Eukaryotes

Question 16

How many residues does Zn cross link in Zn fingers?

Answer 16

4

Question 17

Zn acts as what in a Zn finger?

Answer 17

Stabilizer, holds finger together at base

Question 18

DNA binding with Zn fingers is weak or strong?

Answer 18

Weak

Question 19

A leucine occurs every __ position in a leu zipper

Answer 19

7th

Question 20

What structure does a Leu zipper have?

Answer 20

Amphiphatic alpha helix

Question 21

What are regulatory proteins?

Answer 21

TF’s, activators, repressors

Question 22

What is heterochromatin?

Answer 22

Condensed, transcriptionally inactive

Question 23

What is euchromatin?

Answer 23

Less condensed, transcriptionally active

Question 24

Which histone links together multiple nucleosomes?

Answer 24

H1

Question 25

Name the 5 histones.

Answer 25

H1, H2A, H2B, H3, H4

Question 26

Transcriptionally active chromatin lacks what?

Answer 26

H1

Question 27

Which DNA binding motif can also bind RNA?

Answer 27

Zn fingers

Question 28

Transcriptionally active chromatin is enriched with what?

Answer 28

histone variants (H3.3, H2A2)

Question 29

What do SNF & SWI enzymes do?

Answer 29

Deplete H1, replace with histone variants

Question 30

How are histones usually modified?

Answer 30

1. Lys/Arg: Methylation
2. Ser/Thr: Phophorylation
3. Lys: Sumolaytion or ubiqination

Question 31

What do HATs and HDACs do?

Answer 31

HAT: Adds acetyl
HDAC: removes acetyl

Question 32

How can DNA be methylated?

Answer 32

CpG sequence

Question 33

Describe the assembly of the pre-initiation complex of transcription.

Answer 33

1. TBP and TFIIB bind to promoter (Stabilized by TFIIA)
2. RNA comes to bind @ transcription start site (promotor)
3. TFIIF binds tightly to to pol2 and TFIIB and prevents binding to non specific DNA
4. TFIIE Recuits TFIIH
5. TFIIH unwinds DNA at promoter and phosphortlated pol2 @ CTD

Question 34

What is the preinitiation complex made of?

Answer 34

RNA pol and TF’s

Question 35

What are HMG proteins?

Answer 35

High mobility group, bend DNA yo bring activator (UAS) to promotor

Question 36

Where are Type 1 nuclear receptors found?

Answer 36

In cytoplasm, bound to HSB (chaperones)-dimerize when binding occurs to enter nucleus

Question 37

Where are Type 2 nuclear receptors found?

Answer 37

In nucleus, bound to promotor. Always bound to repressor in inactive state.

Question 38

What do microRNAs do?

Answer 38

Silence genes by cleaving with dicer/drosha or blocking them

Question 39

What do siRNAs do?

Answer 39

Uses dicer to cut hairpin bends=silences mRNA