3.9 Dna Replication And The Genetic Code

Question 1

Why before a cell divides does it need to copy its DNA

Answer 1

To ensure that the two new daughter cells will both receive a complete set of genetic information

Question 2

What is the process known as when DNA is copied

Answer 2

Semi conservative replication

Question 3

What is the end result of semi conservative replication

Answer 3

Each new dna molecule consists of one strand that is conserved and one strand that is newly created

Question 5

When does semi conservative replication takes occur

Answer 5

Occurs during the s phase of the cell cycle

Question 6

Process of semi conservative replication

Answer 6

1. Enzyme dna helicase unwinds double helix breaking hydrogen bonds between the complementary base pairs
2. Free dna nucleotides are attracted to the exposed bases on template strands
3. Adjacent nucleotide are joined by phosphodieser bonds formed in a condensation reaction using dna polymerase
4. Hydrogen bonds formed between complementary bases forming DNA double helix

Question 7

Why is it important to conserve one of the dna strand

Answer 7

• maximises accuracy during dna replication process
• ensures genetic continuity
• ensure new cells carry out same ones as parent cells

Question 8

What are some random, spontaneous mutations

Answer 8

Examples of errors are
- base inserted to complementary stand in wrong order
- extra base being inserted
- base being left out
These mistakes do not have a particular cause

Question 9

What does DNA polymerase do

Answer 9

Catalyses the formation of the phosphodiester bonds between adjacent nucleotides in the sugar phosphate backbone