Lecture 12: Human Genome Organisation File

Question 1

What are transposons ?

Answer 1

a chromosomal segment that can undergo transposition (move)

Question 2

What do transposons cause ?

Answer 2

high mutation rate, as they may land in gene. They also leave chromsome ends that need to be repaired when they jump

Question 3

What 3 things make up a retrotransposon ?

Answer 3

1. inverted repeats (facilitate insertion)
2. gag gene (encoding RNA maturase)
3. pol gene (encoding reverse transcriptase)

Question 4

What is a retrotransposon

Answer 4

transposon that moves via an RNA intermediate

Question 5

What can transposons be used as ?

Answer 5

mutagens

Question 6

What are the two types of human repetitive DNA ?

Answer 6

Lines - long interspersed nuclear elements

Sines - short interspersed nuclear elements

Question 7

What makes up a Line ?

Answer 7

have ORF1 (encodes a nucleic acid chaperone) and ORF2 (encodes reverse transcriptase)

Question 8

What makes up a Sine?

Answer 8

Has no ORF (no genes), so is dependant on transcription from other sources

Question 9

What is the most common sine and what mammals is it found in ?

Answer 9

Alu, found in humans and their close relatives (chimp, gorilla etc)

Question 10

where are Alu elements found ?

Answer 10

Specific regions of specific chromosomes

Question 11

What is the link between no-coding DNA and the complexity of an organism ?

Answer 11

More complex organisms have more no-coding DNA

Question 12

what are the benefits of having no-coding DNA ?

Answer 12

larger distances between genes increases recombination rate( more variation) , also acts as sponge to absorb invading DNA