DNA

Question 1

What do the size and shape of the bases show?

Answer 1

The shapes and sizes of the Nitrogenous bases help us understand why the GC and AT pairs exist in DNA
G &C have 2 rings
A,T and U have 1 ring

Question 2

What are base pairings held by?

Answer 2

Base pairings are held together by weak H2 bonds and they are easy to break
GC- 3 bonds
AT- 2 bonds

Question 3

What is the process of DNA replication?

Answer 3

1) parent strand has 2 strands of DNA, each base is paired by hydrogen bonding
2) The 2 DNA strands are separated, each strand can be a template
3) nucleotides complementary to the parent strand are connected to form sugar, phosphate backbone

Question 4

Order

Answer 4

5’ 3’

3’ 5’

Question 5

What does the old strand do to mark the original strand?

Answer 5

The cell tags the old strand with methylate, then the enzymes scan for mistakes

Question 6

What is the first step in replication?

Answer 6

1) The helicase unwinds and separates the parental DNA strands

Question 7

What is the second step?

Answer 7

2) single-strand binding proteins stabilise the unwound parental strands

Question 8

What is the third step in replication?

Answer 8

Topoisomerase breaks down, swivels and rejoins the DNA ahead of the replication fork and relives stress

Question 9

What is the fourth step in replication?

Answer 9

Primase synthesises the RNA primers using the parental DNA as a template