Eukaryotic Gene Regulation

Question 1

What are three ways chromosomal regions can act as control points?

Answer 1

• Inactivated during development
• Activated by translocation
• Gene deletion

Question 2

What is an example of chromosomal inactivation?

Answer 2

X chromosomes in female

Question 3

What is an example of translocation as regulation?

Answer 3

Variable regions of antibody molecules

Question 4

What is an example of chromosomal material being lost?

Answer 4

Human red blood cell

Question 5

What is Gene reiteration?

Answer 5

The presence of many identical genes

Allows transcripts to be made at a high rate

Question 6

How can the initiation of transcription act as a control point?

Answer 6

Through the use of specific transcription factors that are regulated

Question 7

What are four ways mRNA can be used as a point of regulation?

Answer 7

• alternative splicing
• transportation from the nucleus
• rate of degradation
• masking to an “inactive” form

Question 8

How does histone acetylation affect gene expression?

Answer 8

Acetylated = favors gene expression

Deacetylation = inactive chromatin

Question 9

What is the role of scaffolding proteins in gene expression?

Answer 9

Condense regions of the chromatin (inactive)

Question 10

How does methylation affect gene expression?

Answer 10

DNA methylation favors inactive chromtin

Question 11

What is the role of promoters?

Answer 11

Bind general transcription factors

Question 12

What is the role of enhancers?

Answer 12

Bind specific transcription factors

Act in a tissue-specific manner

‘Target for steroid hormones

Question 13

What is the difference between trans regulators and cis regulators?

Answer 13

Trans regulators – proteins that act on specific DNA sequences

Cis regulators – elements within the DNA that serve regulatory functions (e.g. promoter, enhancer)

Question 14

What are four ways of activating transcription factors?

Answer 14

• Synthesis
• Ligand binding
• phosphorylation
• addition of second subunit

Question 15

How do steroid hormones activate transcription factors?

Answer 15

Through ligand binding

Question 16

What are three common structures of DNA-binding proteins?

Answer 16

• Zinc finger
• Helix-Turn-Helix
• Leucine Zipper

Question 17

Describe Ferritin and Transferrin Receptor translation in low iron.

Answer 17

A protein is active and binds the mRNA of ferritin and transferrin, this promotes the translation of the receptor and represses ferritin.

In high iron, the protein doesn’t bind and the opposite happens

Question 18

What is RNA interference?

Answer 18

Small RNA molecules that bind to the 3’ untranslated region of an mRNA molecule to interfere with translation

Question 19

What is the function of microRNA?

Answer 19

An imperfect match for mRNA, binds and inhibits translation

Question 20

What is the function of short interfering RNA?

Answer 20

An exact match for the 3’ end of mRNA, binds and causes mRNA degredation due to the presence of double stranded RNA

Question 21

What is the cause of Prader-Willi Syndrome?

Answer 21

Deletion on chromosome 15 inherited by the father

The maternal copy is methylated at this region, and therefore inactive.

Hypogonadism, small hands and feet, obesity, mental retardation

Question 22

What is the cause of Angelman syndrome?

Answer 22

Deletion on chromosome 15 inherited by the mother

The paternal copy is methylated at this region, and therefore inactive

seizures, ataxic gait, behavior disorders, mental retardation