2. DNA Replication

Question 1

Why does DNA copy itself?

Answer 1

To ensure that before cell division each new cell has the full amount of DNA.

Question 2

What is the method called when the DNA copies itself?

Answer 2

Semi-conservative replication Because half the strands in each new DNA molecule are from the original DNA molecule.

Question 3

If the new DNA molecules have half the strands from original DNA molecule, what does this mean?

Answer 3

There is genetic continuity between generations of cells - inherit their genes from their parent cells.

Question 4

1. What does the enzyme dna helicase do ?

Answer 4

Breaks hydrogen bonds between bases on the 2 polynucleotide dna strands.

Question 5

2 When dna helicase finishes breaking down these hydrogen bonds, what’s formed?

Answer 5

2 single strands as the helix has unwinded.

Question 6

3. What does each original strand act as ?

Answer 6

A template for a new strand.

Question 7

4 Now one strand of dna is exposed what happens?

Answer 7

Complementary base pairing as free floating DNA nucleotides are attracted to complementary exposed bases on original template strand.

Question 8

5 What nucleotides join with what ?

Answer 8

A - T

C - G

Question 9

6 What reaction joins nucleotides on new strand together ?

Answer 9

Condensation reaction

Catalysed by enzyme DNA polymerase

Question 10

7 when the new strand join together via condensation reaction, what happens?

Answer 10

Hydrogen bonds form between bases from original and new strand.

Question 11

8 so what is the final outcome ?

Answer 11

Each new dna molecule contains one strand from original dna and one new strand.

Question 12

Name 2 enzymes used in dna replication ?

Answer 12

Dna helicase

DNA polymerase