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DNA Replication

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DNA Replication It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic ... – PowerPoint PPT presentation

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Title: DNA Replication


1
DNA Replication
  • It has not escaped our notice that the specific
    pairing we have postulated immediately suggests a
    possible copying mechanism for the genetic
    material
  • Watson and Crick

2
Why do cells need DNA?
  • DNA contains the information cells need to
    function and live.

3
Why do cells need to replicate (copy) their DNA?
  • To make new cells

4
How do cells replicate their DNA?
  1. The DNA double helix is

unwound by an enzyme.
5
  1. Another enzyme moves down the 2 original DNA
    strands and

adds complementary nucleotides.
6
  1. Two separate DNA molecules are formed, each with

one new strand and one old strand.
7
Replication Mistakes
  • 6 billion base pairs per cell.
  • All are replicated in a few hours.
  • Mistake happens one per billion nucleotides.

8
Mistakes Mutations
  • Mutations are changes in the base sequence of the
    DNA molecules.
  • This can have serious affects on genes and the
    functions of cells.
  • Cancer is caused by mutations in DNA.

9
Mutagens
  • Physical or chemical factor that increases the
    frequency of mutations.
  • Examples UV rays, X-rays, smoking

10
3 Types of Mutations
  • Insertion
  • Deletion
  • Substitution

11
Think!
  • Which mutations are potentially the most harmful?
    Why?
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