Lecture 15

Question 1

What are transposable elements?

Answer 1

Mobile DNA which are capable of copying themselves around the genome, which can change and block expression from nearby genes

Question 2

What are the two main classes of transposable elements?

Answer 2

Class I: retrotransposons (copy & paste through RNA)
Class II: DNA transposons (cut & paste via DNA)

Question 3

Why are transposable elements described as selfish genes?

Answer 3

• they will spread continuously until something stops them
• makes multiple copies so more offspring can inherit them
• even if they cause harm, continue to spread if the gains are more than reduction of fitness

Question 4

What is HK2 and how does it affect humans?

Answer 4

Retrotransposable element which has a polymorphic insertion in intron 17 of the gene RASGRF2, is associated with dopaminergic signalling

Question 5

What is ectopic recombination?

Answer 5

Rearrangement which can delete large chunks of the genome and cause damage

Question 6

How does ectopic recombination happen?

Answer 6

The chromosome forms a loop that allows transposons to pair with eachother

Recombination between the paired transposons deleted the intervening region

Question 7

What does drosophila have instead of telomeres?

Answer 7

• Telomerase is lost
• area of telomeres is now taken up by multiple adjacent insertions
• family of transposable elements have become domesticated, so always jump into telomeres