DNA REPLICATION10.4-10-5

1. DNA Replication Depends on Base Pairing

1. The parent DNA molecule is split into two

2. New nucleotides are added to each of the two DNA strands

3. The base pairing rules determine which nucleotide is added If a T is on the original strand an A is added to

the daughter strand If a C is on the original strand a G is added to

the daughter strand.

DNA has an opposite position to each other; also called “opposite orientation” or antiparallel

3’ (three-prime)- has three carbons on the nucleotide and an OH (hydroxyl) group

5’ (five-prime)- has five carbons on the nucleotide and an PO4- (phosphate) group

DNA Replication

2. DNA Replication: A Closer Look

1. Replication starts on the origins of replication

Origins or Replication- replication begins were proteins attach to the DNA molecule.

2. Replication takes places in both directions The result: replication bubbles

3. There can be thousands of “bubbles” at one time as DNA replication takes place in eukaryotic organisms4. DNA polymerases – enzymes that join individual nucleotides to make a new DNA molecule

5. DNA Polymerase adds nucleotides to the 3’ end of the strand; not the 5’ end.

The result: The daughter strand only grows from 5’ to 3’

Replication Forks- the sites where separation & replication take place

The daughter strand is formed in short pieces that need to be connected

6. DNA Ligase- connects the pieces into a single DNA strand

7. Lastly; After the new strand is added DNA Polymerase “proofreads” the new strand to make sure each strand is a perfect copy of the old stand

DNA Replication Video