12-3 DNA Replication

Federoff

Eukaryotic DNA Replication• Step 1 – Helicase unwinds and unzips the DNA

molecule.

• Step 2 – DNA Polymerase adds on complementary nucleotides in a 5’ to 3’ direction.

• Step 3 – The lagging strand continues to replicate in fragments instead of continually like the leading strand.

Okazaki Fragments

• Step 4 – Since the fragments still aren’t joined, the enzyme ligase, joins the fragments.

• Step 5 – As replication continues, the leading and lagging strand twist back into their helical form.

Telomeres• Are the tips of chromosomes that make it less

likely important genes will be lost with replication.

Prokaryotic DNA Replication

• Starts at a single point, and proceeds in 2 directions until the entire chromosome is copied.

Prokaryotic vs. Eukaryotic

• DNA Replication• DNAMovie• Prokaryotic DNA Replication