Chapter 13

Question 1

What is the ground state of eukaryotic gene expression?

Answer 1

OFF due to chromatin compaction.

Question 2

Name the two domains of Gal4 and their functions.

Answer 2

DNA-binding domain (specificity)
Activation domain (interacts with RNA polymerase).

Question 3

What happens to Gal4 when galactose is absent?

Answer 3

Gal80 binds Gal4 and inhibits its function.

Question 4

Define enhancer and its possible locations.

Answer 4

DNA element that binds proteins to enhance transcription; can be upstream or downstream, far from promoter.

Question 5

How can enhancer function be tested experimentally?

Answer 5

Using reporter constructs (e.g., enhancer + lacZ → blue staining in specific tissues).

Question 6

What does histone acetylation do?

Answer 6

Loosens chromatin, making DNA accessible for transcription.

Question 7

Which enzymes add and remove acetyl groups on histones?

Answer 7

HAT adds acetyl groups; HDAC removes them.

Question 8

What is the role of insulators?

Answer 8

Block enhancer-promoter interactions to prevent misregulation.

Question 9

What is genomic imprinting?

Answer 9

Expression of certain genes only from maternal or paternal chromosome due to methylation patterns.

Question 10

Which allele expresses Igf2 in mice?

Answer 10

Paternal allele.

Question 11

What happens when ICR is methylated?

Answer 11

CTCF cannot bind; enhancer activates Igf2; H19 is silenced.

Question 12

Name two epigenetic modifications.

Answer 12

DNA methylation and histone acetylation/methylation.

Question 13

True or False: Enhancers are proteins.

Answer 13

False – they are DNA sequences.

Question 14

True or False: Gal4 is a protein.

Answer 14

True.

Question 15

Codon is on ______; anticodon is on ______.

Answer 15

Codon on mRNA; anticodon on tRNA.

Question 16

What is the end product of the Gal4 pathway?

Answer 16

Enzymes for galactose metabolism.

Question 17

Which histone modification is associated with gene silencing?

Answer 17

Methylation

Question 18

What does SWI/SNF do?

Answer 18

Chromatin remodeling to expose regulatory sequences.

Question 19

True or False: Insulators are proteins.

Answer 19

False – they are DNA elements.

Question 20

What happens if a mutated imprinted gene is inherited from the father?

Answer 20

The phenotype depends on whether the paternal allele is normally expressed.