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DNA Replication

DNA Replication. DNA Replication – What and Why. Replication = DNA making copies of itself DNA must be copied before a cell can divide Each new cell will have a complete set of DNA. History of Replication. Watson & Crick – realized that complementary base pairing

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DNA Replication

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  1. DNA Replication

  2. DNA Replication – What and Why • Replication = DNA making copies of itself • DNA must be copied before a cell can divide • Each new cell will have a complete set of DNA

  3. History of Replication • Watson & Crick – realized that complementary base pairing provided a way for DNA to copy itself - base pairing could allow a new strand to be built on an old strand

  4. DNA Replication • In most prokaryotes, DNA replication begins at a single point and continues in two directions. • In eukaryotic chromosomes, • DNA replication occurs at hundreds of places. • Replication proceeds in both directions until each chromosome is completely copied.

  5. Critical Thinking Check • How does the structure of a eukaryote and a prokaryote relate to the manner in which the DNA is replicated in each?

  6. DNA Replication: Process • Replication begins when the enzyme DNA helicaseopens the DNA forming replication bubbles

  7. DNA Replication: Process • The nitrogen bases on the original DNA strands are exposed in the replication bubbles. • They serve as a template to build new DNA strands

  8. DNA Replication • The ends of the replication bubbles known as the replication fork is where replication begins

  9. DNA Replication – DNA Polymerase • The enzyme DNA polymerase brings new nucleotides to the replication fork - it pairs them according to base pairing rules A pairs with T C pairs with G

  10. DNA Replication • The process continues until 2 complete copies of the DNA are produced • Each copy of the DNA contains one strand of DNA from the original DNA molecule and one new strand that was produced by replication • Known as semi-conservativereplication

  11. DNA Replication

  12. Knowledge Check • Summarize the major events that occur in DNA replication (you should come up with at least 3 unique steps).

  13. Summary of DNA Replication • Hydrogen bonds between base pairs are broken • DNA unwinds – replication bubbles form • Free nucleotides pair up with their respective bases • DNA polymerase proofreads each new strand of DNA • Two double helices are now present

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