DNA Replication Animation

Function of… To replicate DNA with high fidelity Must be done prior to mitosis 1 cell  2 cells, DNA content of new daughter cells must be exactly the same as original parent cell.

Steps required 1: Uncoil the double helix – helicase 2: Create start point for replication – primase inserts RNA primer. 3: Insert free nucleotides using base- pairing rule

Steps required 2 4: DNA polymerase III assembles new strand using free nucleotides. 5: DNA polymerase I replaces RNA primers with DNA 6: DNA ligase anneals (connects) new DNA fragments into continuous strands.

Products Original helix is split in 2 and one half of each helix ends up in new DNA helix – semi-conservative replication. A-T and C-G pairing rules act as error- correcting mechanism. DNA is replicated at a speed of base pairs/second.

Okazaki fragments The 2 strands of a helix run in opposite directions 3’  5’ and 5’  3’ DNA polymerase attaches nucleotides in a 5’  3’ direction. As a result only one strand can be synthesized continuously, the other strand must be assembled from fragments.