Regulation of Gene Expression

Question 1

Define differential gene expression

Answer 1

Some genes are expressed while others are repressed

Question 2

Old and new concepts related to genetic switches

Answer 2

Old: “loss” of genes
New: genes can be turned “on” or “off”

Question 3

Importance of regulation of gene expression (3), give examples of each

Answer 3

1. adaptation to environmental changes –> ex. memory B cell antibody production during immune response
2. development –> ex. pluripotential stem cells
3. differentiation of cells –> ex. specific proteins for specific cell function

Question 4

Levels of eukaryotic gene regulation (6)

Answer 4

1. epigenetic control
2. transcriptional control
3. post-transcriptional control
4. RNA transport control
5. Translational control
6. Post-translational control

Question 5

Heterochromatin vs Euchromatin

Answer 5

1. heterochromatin –> dense, transcriptionally silent, tightly packed, inaccessible to polymerases and other enzymes
2. euchromatin –> loosely packed and active in gene transcription

Question 6

Define chromatin remodeling

Answer 6

Interconversion of heterochromatin and euchromatin

Question 7

a) structure and b) significance of telomeres

Answer 7

a) complexes of DNA and proteins at the end of chromosomes
b) maintain structural integrity, prevent attack by nucleases, allow repair systems to differentiate between ends and breaks

Question 8

Mechanisms to increase/decrease access to DNA sequence (2)

Answer 8

1. gene regulatory proteins

2. RNA polymerases

Question 9

Mechanisms to alter chromatin structure (2)

Answer 9

1. cytidine methylation

2. histone methylation

Question 10

Principle of DNA methylation

Answer 10

1. Silencing genes to reduce unnecessary gene expression

2. Methylation of CG dinucleotide (CpG) causes silenceing