Download 8.3 DNA Replication

8.3 DNA Replication
KEY CONCEPT
DNA replication copies the genetic information of a
cell.
8.3 DNA Replication
In replication, the DNA is copied during the cell cycle
• DNA is replicated during the
S (synthesis) stage of interphase
Overview:
• A single strand of DNA serves as
a template for a new strand.
• The rules of base pairing direct
replication.
– A pairs with T
– C pairs with G
• Each body cell gets a
complete set of
identical DNA.
8.3 DNA Replication
Proteins carry out the process of replication.
• DNA serves only as a template…enzymes and other
proteins do the actual work of replication.
1. Enzymes unzip the double helix in two directions
at the same time.
2. Free-floating nucleotides pair with the exposed
bases on the template strand (and they form
hydrogen bonds here).
2. nucleotide
1. Sugar Phosphate
Backbone
The DNA molecule unzips
in both directions.
8.3 DNA Replication
3. DNA polymerase enzymes bond the new nucleotides
together to form the double helix.
4.new strand
2. nucleotide
3.DNA polymerase
8.3 DNA Replication
The end result:
4. Two new molecules of DNA identical to the original
molecule result; each with an original and new strand.
• DNA replication is semiconservative.
original strand
Two molecules of DNA
new strand
8.3 DNA Replication
Replication is fast and accurate.
• DNA replication starts at many points in eukaryotic
chromosomes.
There are many origins of replication in eukaryotic chromosomes.
• DNA polymerases can find and correct errors.