1. 7.2 DNA REPLICATION What are the steps in DNA replication?
Key Concepts
Vocabulary
What are the steps in DNA replication?
Why does DNA need to be replicated?
Replication
Template

2. DNA Replication Replication – the process of copying a DNA molecule.
It replicates so the genetic info can be passed on to the next generation.
DNA replicates before cells divide
(during interphase)

3. Quick Review… DNA is made up of 2 strands of nucleotides.
The strands are held together by HYDROGEN BONDS
The 2 strands are COMPLEMENTARY
A pairs with T
C pairs with G

4. HOW IT WORKS
During replication EACH strand is used as a pattern (template) to make 2 new DNA molecules
AND
Original
DNA
Original LEFT with
new right strand
Original RIGHT with new left strand

5. Steps in DNA Replication
Double helix shape unwinds.
An ENZYME “unzips” the DNA molecule, breaking the hydrogen bonds between the strands
Unpaired
bases
DNA polymerase
(enzyme)

6. Free nucleotides in the nucleus pair up with the nucleotides on the DNA strands forming new hydrogen bonds.
Original
DNA
DNA
unzips
Free nucleotides pair up with the original LEFT strand
Free nucleotides pair up with the original RIGHT strand

7. The DNA winds back up into a double helix.
The final products of DNA replication are two strands of DNA each having half new material and half old material.

8. Why Replicate?
So genetic information can be passed onto new cells during cell division.
2 new identical cells
DNA copied

9. Accuracy
Replication is also very accurate – only ONE IN A BILLION base pairs are incorrectly paired.
When mistakes are made, the DNA molecule can correct itself so the genetic code remains the same.