1. 1 DNA Replication copyright cmassengale http://www.youtube.com/watch?v=9u4Zo7U Vyi4

2. What is replication? The process of making an EXACT copy of DNA. Why does the copy need to be EXACT? copyright cmassengale2

3. 3 When does replication occur? DNA has to be copied before a cell dividesDNA has to be copied before a cell divides New cells will need identical DNA strandsNew cells will need identical DNA strands When do you need new cells? Growth, healing, making sex cells…When do you need new cells? Growth, healing, making sex cells… copyright cmassengale

4. Replication video http://www.youtube.com/watch? v=4jtmOZaIvS0&feature=relatedhttp://www.youtube.com/watch? v=4jtmOZaIvS0&feature=related copyright cmassengale4

5. 5 DNA Replication Helicase (a protein called an ENZYME) unwinds and separates the 2 DNA strands by breaking the weak hydrogen bondsHelicase (a protein called an ENZYME) unwinds and separates the 2 DNA strands by breaking the weak hydrogen bonds Single-Strand Binding ProteinsSingle-Strand Binding Proteins attach and keep the 2 DNA strands separated and untwisted copyright cmassengale

6. 6 DNA Replication DNA polymerase can then add the new nucleotides What chemical reaction is this? copyright cmassengale

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8. 8 Proofreading New DNA DNA polymerase initially makes about 1 in 10,000 base pairing errors (MUTATIONS)DNA polymerase initially makes about 1 in 10,000 base pairing errors (MUTATIONS) If you have about 3 billion base pairs, how many errors is this?If you have about 3 billion base pairs, how many errors is this? copyright cmassengale

9. Telephone – the written version One side of the room versus the other. You need a scrap piece of paper and something to write with. copyright cmassengale9

10. DNA polymerase proofreads and correct these mistakesproofreads and correct these mistakes The new error rate for DNA that has been proofread is 1 in 1 billion base pairing errorsThe new error rate for DNA that has been proofread is 1 in 1 billion base pairing errors Much better!!!Much better!!! copyright cmassengale10

11. 11 Semiconservative Model of Replication Idea presented by Watson & CrickIdea presented by Watson & Crick TheThe two strands of the parental molecule separate, and each acts as a template for a new complementary strand New DNA consists of 1 PARENTAL (original) and 1 NEW strand of DNA Parental DNA DNA Template New DNA copyright cmassengale

12. 12 DNA Damage & Repair Chemicals & ultraviolet radiation damage the DNA in our body cells Cells must continuously repair DAMAGED DNA Excision repair occurs when any of over 50 repair enzymes remove damaged parts of DNA DNA polymerase and DNA ligase replace and bond the new nucleotides together copyright cmassengale

13. <3 copyright cmassengale13

14. 14 Question: What would be the complementary DNA strand for the following DNA sequence? DNA 5’-CGTATG-3’ copyright cmassengale

15. 15 Answer: DNA 5’-CGTATG-3’ DNA 3’-GCATAC-5’ copyright cmassengale

16. 16copyright cmassengale