Gene Organisation

Question 1

Gene structure (5)

Answer 1

Contains 4 nucleotides: 
Adenine
Cytosine 
Guanine 
Thymine 

Attached via a phosphate-sugar backbone

Question 2

How does guanine pair cytosine

Answer 2

3 hydrogen bonds

Question 3

How does adenine pair with thymine

Answer 3

2 hydrogen bonds

Question 4

DNA methylation (5)

Answer 4

Due to methyl groups being added to cytosine at CpG sites
Forms 5-methylcytosine
Stably silences gene expression
DNA methylation is typically permanent
Helps establish cell specificity from pluripotent cells

Question 5

Epigentics (4)

Answer 5

Heritable alterations in gene expression without changes in DNA sequence Involves chromatin modifications referred to as gene silencing
DNA methylation is an example of epigenetic modifications
Changes can be copied though cell division

Question 6

What can cause epigenetic modifications (5)

Answer 6

Development
Environmental chemicals 
Drugs
Ageing 
Diet

Question 7

What diseases may involve epigenetic modifications (4)

Answer 7

Cancers
Autoimmune diseases
Mental disorders
Diabetes

Question 8

Role of untranslated regions (3)

Answer 8

Efficiency of translation
Stability of mRNA
Subcellular localisation of mRNA

Question 9

Define gene (2)

Answer 9

Stretch of DNA that encodes for a polypeptide

Only 1-2% of human genome directly encodes for proteins