Chromosome structure and function

Question 1

What are the roles of proteins in chromosomes?

Answer 1

1. Package and unfold DNA
2. Control DNA replication
3. Maintain chromosome integrity
4. Govern proper chromosome segregation
5. Regulate gene expression

Question 2

Whats a telomere?

Answer 2

DNA sequences at the end of linear chromosomes

Question 3

What is the centromere?

Answer 3

DNA sequences on which the kinetochore assembles and mediates chromosome segregation

Question 4

What is the kinetochore?

Answer 4

A protein complex that binds microtubules in the the mitotic spindle

Question 5

What are telomeres replicated by?

Answer 5

Special DNA polymerase- telomerase

Question 6

What is a nucleosome?

Answer 6

A core protein with DNA wound around it

Question 7

What is a chromosome?

Answer 7

A highly coiled fibre of chromatin

Question 8

What are the subunits of the nucleosomes called?

Answer 8

Core histones

Question 9

What is H1 and what does it do?

Answer 9

Linker histone

Straps DNA onto histone octomers and limits the movement of DNA

Question 10

What are transposons?

Answer 10

Repeated DNA sequences

mobile, genetic elements that jump around the genome

Question 11

3 examples of transposons

Answer 11

1. DNA transposons
2. Retroviral retrotransposons
3. Non-retroviral polyA retrotransposons

Question 12

What does transposase do?

Answer 12

‘Cut and paste’ transposons - moving them around the genome

Question 13

How do retroviral transposons behave?

Answer 13

Replicate via RNA intermediates- uses own reverse transcriptase- produce new DNA copes that integrate at new genomic locations

Question 14

How do non-retroviral transposons behave? 2 examples of such transposons

Answer 14

Replicate via RNA intermediates- uses own reverse transcriptase
Human L1 elements
Human Alu elements
Mouse B1 element

Question 15

What are possible implications of some L1 insertions?

Answer 15

Can disrupt genes- cause disease e.g haemophilia