Download - DNA Replication DNA is replicated before cell division, when a cell divided into two cells
DNA Replication
DNA is replicated before cell division, when a cell divided into
two cells
• Enzymes help DNA replication occur.– Helicase- unzips the two stands of DNA
breaking the hydrogen bonds that hold them together.
– DNA Polymerase adds complementary nucleotides A-T G-C
– DNA Ligase connects fragments of DNA on the lagging stand to make a continuous molecules.
Replication fork
DNA polymerase
New strand
Original strand DNA
polymerase
Nitrogenous bases
Replication fork
Original strand
New strand
Proofreading
• After the two daughter strands are complete, other enzymes “proof read” the DNA checking the original or parent strand.
• DNA Polymerase makes about 1 mistakes in ever 500 base pairs, but after proofreading as few as 1 mistake in a billion base pairs can be found… Helping to prevent mutation from occurring!!
