Unit 1.2

Question 1

DNA can reproduce itself, this is called

Answer 1

Replication

Question 2

DNA replication stages

Answer 2

1) DNA double helix unwinds
2) weak hydrogen bonds break causing 2 strands to separate (unzipped)
3) free DNA nucleotide joins complimentary pair on open strand
4) weak hydrogen bonds reform between base pairs
5)strong chemical bond forms between both nucleotides
6)newly formed daughter DNA (identical to original) begins to wind into double helix

Question 3

What enzyme controls stage 5 of DNA replication

Answer 3

DNA polymerase

Question 4

What does DNA polymerase need to be present before it can start replicating DNA?

Answer 4

Primer

Question 5

DNA replication can only occur from what ends due to DNA polymerase enzymes only adding nucleotides to the 3’end

Answer 5

5’ end to 3’ end

Question 6

Leading strand

Answer 6

DNA polymerase can only add nucleotides to the 3’ end of the growing strand meaning that one strand is continuously replicated

Question 7

Lagging strand

Answer 7

Due ato the antiparallel of the DNA and only adding nucleotides to the 3’ end the opposite strand is replicated in fragments

Question 8

Fragments on the lagging strand are joined together using the enzyme

Answer 8

Ligase

Question 9

What is PCR used for?

Answer 9

To amplify DNA fragments in vitro to create many copies of the fragments

Question 10

Initial requirements for PCR

Answer 10

-DNA template
-nucleotides
-heat tolerant
-complimentary primers
-thermal cycler

Question 11

What are complimentary primers needed for in PCR

Answer 11

To target specific DNA

Question 12

Practical uses of PCR?

Answer 12

Paternal use
Forensic use
Diagnose genetic disorders

Question 13

Stages of PCR

Answer 13

1) DNA is heated to 95 degrees to break H bonds and separate DNA strands
2)cooled to 55 degrees for complementary primer to anneal
3) heated back up to 75 degrees for a heat tolerant DNA polymerase and to replicate the region of DNA