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DNA Replication

DNA Replication. Chapter 10. Review of DNA and RNA. 1. Which has ribose of the sugar? 2 . Which is double stranded 3 . Thymine if found in DNA - what is found in RNA instead? 4 . Which base does cytosine pair with? 5 . What makes up the “back bone” of DNA?. DNA replication.

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DNA Replication

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  1. DNA Replication Chapter 10

  2. Review of DNA and RNA • 1. Which has ribose of the sugar? • 2. Which is double stranded • 3. Thymine if found in DNA - what is found in RNA instead? • 4. Which base does cytosine pair with? • 5. What makes up the “back bone” of DNA?

  3. DNA replication • Carried out by enzymes • 1st enzyme (helicase) - “unzips” the 2 strands of DNA (i.e. breaks H bonds), separating base pairs

  4. After unzipping • Each of the separated strands serves as a “template” for making a new double strand

  5. As strands unzip • Replication fork - where 2 strands separated • DNA Polymerase adds complementary base pairs to the exposed bases • Bases can only be added in the 5’-3’ direction

  6. How bases are added • One strand is filled in unbroken; the other strand uses okazaki fragments • Okazaki fragment gaps are filled in by the enzyme DNA ligase

  7. Replication • Occurs at many places along a DNA strand • DNA polymerase - adds about 50-100 new nucleotides per second

  8. As a result... • Two identical DNA molecules result • Mitosis or Meiosis can now occur

  9. Errors in pairing • Can result in mutations • Mutations can be harmful, beneficial or have no effect

  10. Types of Mutations • Point Mutation- An incorrect base is added to a pair in one spot affecting a single amino acid.

  11. Types of Mutation • FrameshiftMutation- Moves the entire frame of DNA • Insertion- An extra base is added in where one should not be shifting the entire reading frame. • Deletion- A base is deleted shifting the entire reading frame back one.

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