Evinmental Effects And Epigeteics

Question 1

What is phenotype determined by

Answer 1

1. Genotype
2. Environment

Question 2

Epigentics

Answer 2

Environmental factors that affect the way genome is expressed without altering genetic code
Generate many phenotypes from same genotype

Question 3

Common structural proteins and enzymes

Answer 3

Histones
RNA polymerase
Tubular - part of cytoskeleton
Pyruvate kinase - glycolysis

Question 4

Genes are transcriptional units composed of…

Answer 4

Structural info - coding for protein
Regulatory sequences - giving instructions for expression. Upstream

Question 5

Histone modification

Answer 5

Histone are subject to chemical modifications

E.g. acetylation/ methylation

Question 6

What controls gene expression

Answer 6

1. Transcriptional control
2. RNA processing control - splicing
3. RNA transport
4. Translational control
5. Protein activity control

Question 7

Enhancers?

Answer 7

DNA sequences upstream and downstream a gene which recruit TF and bind to them

Question 8

Role of TF

Answer 8

Decide whether RNA polymerase should be active or inactive
Often TF respond to environmental signals and stress - hormones, nutritional signals

Question 9

Location of promoter region

Answer 9

Before transcription start site but in front of enhancer region.

Question 10

Nucleosome

Answer 10

Globular ball of protein
Contains 8 histones (4 different types)
140bps of DNA wrapped around twice
Nucleosome every 200 bps (naked zone 60bp)

Question 11

Histone tails?

Answer 11

Chains of aa that have chemical tags on them e.g. acetyl and methyl tags
Subject to chemical modifications (post translational)

Question 12

Epigenetic mechanism

Answer 12

Chemical modifications on tails on nucleosomes carry info determining when genes attached to them should be on/ off

Question 13

What is gene activity determined by

Answer 13

• Level of enzymes
  Which is determined by the environment
  Environment can inhibit or activate enzymes

Question 14

What does acetylation do to the histone tails

Answer 14

• Open conformation of chromatin as acetylated histones cannot package closely
• So TF can bind to enhancers and RNA polymerase has access to gene

Question 15

Epigenetic therapy

Answer 15

Involved altering gene expression at enzymatic level

Question 16

X inactivation?

Answer 16

Random process not environmental - heritable Epigenetic state
One of the Xs in females inactivated in early development- blastocyst
Balances the difference between males and females

Question 17

Ways that gene expression is controlled

Answer 17

Epigenetic mechanisms (e.g. histone modifying enzymes)

Gene specific TF

Question 18

Promoter region

Answer 18

Upstream and immediately adjacent ti coding region there is a 5’ regulatory sequence

Question 19

Dosage compensation

Answer 19

Equalises the amount of gene product that comes whether you have one or two copies of the X chromosome