Mitosis and Meiosis

Question 1

What are the DNA Bases?

Answer 1

Purines: Adenine and Guanine
Pyrimidines: Cytosine and Thymine

Question 2

What is an Okazaki fragment?

Answer 2

Short, newly synthesized DNA fragments.
Formed on the lagging template strand
During DNA replication

Question 3

What is A-DNA and its main use?

Answer 3

Right handed
11 Bases per turn
Used for protein complexes

Question 4

What is B-DNA?

Answer 4

Right handed
10.5 bases per turn
most common form of DNA
‘Canonical DNA’

Question 5

What is Z-DNA?

Answer 5

Left handed
Alternating purine, pyrimidine tracts
12 bases per turn
Used for gene regulation and DNA instability

Question 6

What is H-DNA

Answer 6

Triplex DNA
involved in gene regulation

Question 7

Briefly describe the organisation of polynucleotide chains into Chromosomes

Answer 7

Polynucleotide chains form a double helix.
Supercoiling:
DNA wraps around histones to form nucleosomes.
packed nucleosomes forms fibres of chromatin.
Condenses further to form chromosome

Question 8

Why is mitosis predominantly used?

Answer 8

For growth and repair

Question 9

what does postmitotic mean?

Answer 9

non-dividing (e.g. muscle cells)

Question 10

General name given for the products of meiosis

Answer 10

Gametes

Question 11

how does fertilisation create variation?

Answer 11

Mate choice.
Sperm competition.