module 7 lec 12

Question 1

What are activators in transcription regulation?

Answer 1

Activators are transcription factors that help recruit basal factors and RNA polymerase II to the promoter to initiate transcription.

Question 2

How do activators assist in transcription initiation?

Answer 2

Activators recruit basal factors and RNA polymerase II to the promoter, facilitating the start of transcription.

Question 3

What is the role of coactivators in transcription regulation?

Answer 3

Coactivators are proteins that help activate transcription by altering chromatin structure or recruiting transcription machinery.

Question 4

How do coactivators affect chromatin?

Answer 4

Coactivators, such as histone acetyl transferases (HATs), modify chromatin structure to make it more accessible for transcription.

Question 5

What is the role of Histone Acetyl Transferases (HATs) in transcription

Answer 5

HATs add acetyl groups to histones, which relaxes chromatin and promotes transcription.

Question 6

How do chromatin remodeling complexes assist transcription?

Answer 6

Chromatin remodeling complexes reposition or restructure nucleosomes, making the DNA more accessible for transcription.

Question 7

What are the typical domains of an activator protein?

Answer 7

An activator protein usually has 2 or 3 domains:

DNA binding domain
Activation domain (for basal factors or coactivators)
Sometimes a dimerization domain

Question 8

What is the function of the DNA binding domain in activators?

Answer 8

The DNA binding domain allows the activator to bind to specific DNA sequences in the promoter or enhancer regions to regulate transcription.

Question 9

What is the role of the activation domain in activators?

Answer 9

The activation domain interacts with basal transcription factors and coactivators to initiate transcription

Question 10

What is a leucine zipper in transcription factors?

Answer 10

A leucine zipper is a common structural motif in activators, involved in protein dimerization, where leucines form hydrophobic interactions.

Question 11

What are helix-turn-helix domains?

Answer 11

Helix-turn-helix is a well-conserved DNA binding motif found in activators like the Lac repressor, allowing them to interact with DNA.

Question 12

What is the function of a zinc finger in transcription factors?

Answer 12

A zinc finger is a DNA-binding domain that uses zinc ions to stabilize the structure, allowing the activator to bind to specific DNA sequences.

Question 13

What is a leucine zipper in transcription factors?

Answer 13

A leucine zipper is a structural motif in transcription factors that facilitates dimerization, where two protein subunits bind together through hydrophobic interactions between leucine residues.

Question 14

How does the leucine zipper work?

Answer 14

It helps two protein subunits bind together, enabling DNA binding and gene activation.

Question 15

What amino acid is key in leucine zippers?

Answer 15

Leucine residues spaced every 7th amino acid.

Question 16

Why is leucine zipper important for transcription?

Answer 16

It stabilizes DNA-protein interactions and enhances transcription factor binding.

Question 17

What do repressors do in transcription?

Answer 17

Repressors prevent gene activation by blocking RNA pol II binding or recruiting corepressors.

Question 18

How do repressors block transcription?

Answer 18

They recruit corepressors that modify histones, keeping chromatin in a closed state.

Question 19

What is the structure of a repressor?

Answer 19

Similar to activators, with DNA binding and repression domains.

Question 20

How do repressors inhibit activators?

Answer 20

They interfere with activators’ ability to recruit RNA pol II or other transcription factors.

Question 21

What is indirect repression?

Answer 21

Repressors prevent transcription by interfering with activator functions, not directly blocking RNA polymerase.

Question 22

What is the role of transcription factors in gene regulation?

Answer 22

Transcription factors help regulate gene expression by binding to specific DNA sequences, often at enhancers or promoters.

Question 23

How many human genes are estimated to encode transcription factors?

Answer 23

About 2,000 out of 25,000 human genes encode transcription factors.

Question 24

Where does cell-specific transcriptional regulation often occur?

Answer 24

At the enhancer regions of DNA

Question 25

Can a single gene have multiple enhancer

Answer 25

Yes, a gene may contain several enhancers, each active in different cell types or under specific conditions.

Question 26

What are enhancers in gene regulation?

Answer 26

Enhancers are DNA regions that increase the transcription of a gene, often influencing tissue-specific gene expression.

Question 27

What is the role of allosteric interactions in transcriptional regulation?

Answer 27

Allosteric interactions involve changes in the shape or activity of transcription factors, often in response to binding of small molecules or other proteins.

Question 28

How do transcription factor modifications regulate gene expression?

Answer 28

Modifications, such as phosphorylation, alter the activity, stability, or DNA-binding ability of transcription factors, influencing gene expression.

Question 29

What is an example of a transcription factor modification?

Answer 29

Phosphorylation by kinases is a common modification that can activate or deactivate transcription factors.

Question 30

What are transcription factor cascades?

Answer 30

Transcription factor cascades are a series of sequential activations, where one transcription factor activates others, amplifying the gene expression response.