DNA Replication

DNA Replication Replication = DNA copies itself exactly (Occurs within the nucleus) Must do this before a cell can divide so both cells will then have identical copies of DNA Any mistake in copying = mutation DNA mutation = chromosomal mutation

A. Basic Facts of DNA Replication 1. Complementary base pairing makes replication possible C - G A - T

A. Basic Facts of DNA Replication 2. One side of DNA molecule is a template for making the other side (strand) ?’s 1-3

B. Process of DNA Replication Uncoil & unzip DNA molecule Enzyme HELICASE breaks weak Hydrogen Bond between bases This happens at the REPLICATION FORK

B. Process of DNA Replication 2. Enzyme DNA POLYMERASE brings in complementary Nitrogenous bases/new nucleotides DNA Polymerase

LIGASE puts the strands back together C - G A - T

Enzyme Review 1st Helicase=unwinds and breaks the bonds 2nd DNA Polymerase=Brings new bases and nucleotides 3rd Ligase=bonds the strands back together

C. Semi-conservative replication Each new DNA molecule contains one old strand & one new strand

End Product of DNA Replication