Chapter 17

Question 1

Three classes of transcriptional activators

Answer 1

• General TXN Factors (GTF)
• Activators
• Co-Activators

Question 2

What type of compound is an activator

Answer 2

Protein

Question 3

Where do activators bind

Answer 3

distal enhancer sequences

Question 4

What do GTFs do?

Answer 4

Bind to TATA Box (core promoter region) and recruit RNA pol

Question 5

What do activators stimulate?

Answer 5

transcription initiation

Question 6

DNA binding proteins are composed of?

Answer 6

• DNA binding domain
• activation domain

Question 7

Do co-activators bind to DNA

Answer 7

No couples action of activator to GTFs

Question 8

What is a co-activator

Answer 8

large multi-protein complex

Question 9

What do repressors do

Answer 9

Inhibit activator from starting transcription initiation (block function of activator)

Question 10

Ways that the repressor can inhibit the activator

Answer 10

• Repressor binding site may overlap with activator binding site
• The repressor domain interacts with the activation domain
• Can recruit corepressors (prevent co-activators)

Question 11

The two domains of a repressor

Answer 11

• DNA binding
• repression domain

Question 12

Combinatorial control

Answer 12

the strategy of controlling TXN in which any gene is controlled by a combination of factors

Question 13

TXN factors

Answer 13

bind to DNA and recruit RNA pol to the promoter.

Question 14

Structural motifs possessed by DNA binding domains

Answer 14

• Helix-turn-Helix
• Zinc Finger
• Leucine zipper

Question 15

Hormone

Answer 15

effector module produced by a cell affects another cell

Question 16

Three major types of hormones

Answer 16

• Protein hormones
• steroid hormones
• amine hormones

Question 17

Protein hormones

Answer 17

• composed of Amino Acids

Question 18

Steroid hormones

Answer 18

• composed of lipids

Question 19

Amine hormones

Answer 19

• composed of amino acids with modified groups

Question 20

Function of polypeptide hormones

Answer 20

bind to receptors in plasma membrane of the cell and trigger a cascade of signal transduction pathway responses.

Question 21

Function of steroid hormone

Answer 21

diffuses through plasma membrane and binds to the cytoplasmic receptor SHR.

Question 22

What happens after the steroid hormone binds to the SHR

Answer 22

The complex binds to the genome and alters gene expression.

Question 23

Why are certain cells targetted by hormones but not other

Answer 23

Only cells with that specific hormone receptor can be affected by that hormone

Question 24

Why are steroid hormone receptors located inside the target cells

Answer 24

Steroid hormones are non-polar and can easily diffuse through the plasma membrane

Question 25

Why are peptide hormone receptors located on the surfaces of cells

Answer 25

peptide hormones cannot diffuse through the cell without a transport channel.

Question 26

Chromatin remodeling epigenetic changes

Answer 26

- gene silencing - genomic imprinting

Question 27

Euchromatin

Answer 27

- TXN active - Interphase of cell cycle (S-phase) - DNase accessible (cuts DNA)

Question 28

Heterochromatin

Answer 28

- TXN Inactive - Mitosis - DNase inaccessible

Question 29

What protein binds the DNA and condenses it?

Answer 29

Histones

Question 30

What is a nucleosome?

Answer 30

Histone + DNA

Question 31

What does histone binding repress?

Answer 31

Gene expression

Question 32

Nucleosome-free regions are:

Answer 32

DNase 1 hypersensitive sites (first to be cut by DNase 1)

Question 33

Lysine acetylation

Answer 33

transfer of an acetyl group from acetyl-CoA to the primary amine of the lysine chain

Question 34

These compounds Add acetyl groups to the histone tail

Answer 34

- Histone acetyltransferases (HATs) -lysine acetyltransferases (KATs)

Question 35

Chromatin Remodeling steps (lysine acetylation)

Answer 35

1. recruited to chromatin by activators 2. acetylates lysines of amino-terminal tails of histones

Question 36

Histone deacetylase (HDACs)

Answer 36

removes acetyl groups from histone tails

Question 37

Nucleosome remodeling complexes

Answer 37

- ATP-dependent - Similar to KAT complexes

Question 38

Steps to Chromatin remodeling (Nucleosome)

Answer 38

- Complexes recruited by activators - Complexes remodel/ move nucleosomes to permit transcription

Question 39

Function of Nucleosome remodeling complexes

Answer 39

- Slide nucleosome - restructure the nucleosome in place - transfer nucleosome to another DNA

Question 40

Gene Silencing

Answer 40

regulation of gene expression in a cell to prevent the expression of a certain gene

Question 41

Why does gene silencing occur?

Answer 41

Occurs because of the location of the gene

Question 42

Example of gene silencing

Answer 42

telomeres

Question 43

Telomeres

Answer 43

- heterochromatin - ends of chromosomes - tandem repeat DNA sequences

Question 44

Telomere position causes

Answer 44

Gene silenicng (genes to be turned off)

Question 45

Telomere position effect is caused by

Answer 45

Silent Information Regulation Proteins (SIR)

Question 46

SIR Steps

Answer 46

1. Rap 1 protein binds to tandem repeat in telomere 2. Rap 1 protein recruits SIR silencing complex 3. SIR2p deacetylates, which leads to heterochromatin condensation and transcriptional inactivation