1. KEY CONCEPT DNA replication makes an exact copy of DNA.

2. DNA Replication:
Why?
So each cell at the end of mitosis will have the exact same DNA
When?
In interphase (S period)
Where?
In the nucleus

3. How Replication occurs:
An enzyme “unzips” the DNA by breaking weak hydrogen bonds between Nitrogen bases
nucleotide
The DNA molecule unzips in both directions.

4. 2. Free-floating nucleotides bond to each side of the DNA strands.
3. Enzymes form covalent bonds in the new strands.
DNA polymerase
new strand
nucleotide

5. Other enzymes “proofread” the new DNA and make necessary repairs
(errors are limited to approximately one error per 1 billion nucleotides)