1. Unit 7b – Replication
Chapter 8.3

2. Replication copies the genetic information (DNA).
Replication is when 1 strand becomes 2 strands
The original strand is the template for the new strand
The base pairing rules direct replication.
DNA is replicated during the S (synthesis) stage of the cell cycle.
When S phase is done,
you have double DNA.

3. Proteins control the process of replication.
DNA is only the template.
Enzymes (proteins) do the actual work of replication.
1st - The enzyme “Helicase” unzips the DNA
-- Now the bases are exposed and need buddies
2nd – There are always extra bases, they find their buddies
nucleotide
The DNA molecule unzips in both directions.

4. Polymerase enzymes form covalent bonds between
3rd – The enzyme DNA polymerase bonds the new buddies together to form the double helix.
Polymerase enzymes form covalent bonds between
nucleotides in the new strand (works like glue)
4th – Proofreader enzymes (a different polymerase) check for errors
DNA polymerase
new strand
nucleotide

5. DNA replication is semiconservative – this is part old and part new.
Two new molecules of DNA are now formed, each with an original strand and a newly formed strand.
DNA replication is semiconservative – this is part old and part new.
original strand
new strand
Two molecules of DNA

6. Replication is fast and accurate.
DNA replication starts at many points in eukaryotic chromosome. If
There are many origins of replication in eukaryotic chromosomes.
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