DNA and Replication

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Replication of Strands

Replication Fork

Point of Origin

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Proofreading New DNA

DNA polymerase initially makes about 1 in 10,000 base pairing errors

Enzymes proofread and correct these mistakes

The new error rate for DNA that has been proofread is 1 in 1 billion base pairing errors

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Semiconservative Model of Replication

Idea presented by Watson & Crick

The 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

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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

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Question:

What would be the complementary DNA strand for the following DNA sequence?

DNA 5’-CGTATG-3’

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Answer:

DNA 5’-CGTATG-3’

DNA 3’-GCATAC-5’

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