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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 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 • Carried out by a series of enzymes • First enzyme (helicase) - “unzips” the 2 strands of DNA (i.e. breaks H bonds), separating base pairs
After unzipping • Each of the separated strands serves as a “template” for attachment of complementary bases
As strands unzip • Replication fork - where 2 strands separated • Complementary base pairs then added to the exposed bases with help of DNA polymerase
How bases are added • Bases added to strands in opposite directions • Gaps are filled in by the enzyme DNA ligase
Replication • Occurs at many places along a DNA strand • DNA polymerase - adds about 50-100 new nucleotides per second
As a result... • Two identical DNA molecules result • Mitosis or Meiosis can now occur
Errors in pairing • Can result in mutations • Mutations can be harmful, beneficial or have no effect