1. DNA Replication To make two identical copies of DNA, the double helix is unwound and each strand is used as a template to make new strand. Complementary pairing (A with T, C with G) allows for exact copying. Complementary base is added to template. At the end of replication, one strand is original and one is new in each of the 2 DNA molecules created.

2. Enzymes involved in DNA Replication Helicase: An enzyme that unwinds the double helix. DNA polymerase (III): An enzyme that synthesizes new DNA by adding complementary nucleotides.

3. Other enzymes act as “spell checkers” to make sure that the DNA is copied correctly. A mistake in replication, or mutation, only occur rarely.

4. DNA Replication Video Click once on image to start https://www.youtube.com/watch?v=z685FFqmrpo

5. Overview of DNA Replication Video Click once on image to start

6. At the end of DNA replication, each of the new DNA molecules has one original strand and one new strand.

7. DNA Replication Animation http://www.stolaf.edu/people/giannini/flashani mat/molgenetics/dna-rna2.swf

9. Review of Concepts When does DNA replication occur? It occurs during the S phase of interphase prior to a cell division (either mitosis or meiosis). The identical copies then condense during prophase to form the sister chromatids.