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DNA

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... Rosalind Franklin photograph DNA. 1952 Alfred Hershey and Martha Chase confirm DNA as genetic material ... 1953 James Watson and Francis Crick model DNA. So? ... – PowerPoint PPT presentation

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Title: DNA


1
DNA
  • Read 158-176
  • HW pg 163 1-3
  • Get binder and tri-fold board

2
Announcements
  • Next test is December 15/16 (Monday and Tuesday
    before break)
  • Test covers material from Mitosis through DNA
  • Science Fair is due NEXT WEEK
  • Next week all class time will be science fair time

3
History
  • Before we move into DNA, its important to track
    the historical discoveries along the way.
  • 1866 Mendel observes inheritance using pea plants
  • 1868 Friedrich Miescher extracts DNA from pus
  • 1903 Walter Sutton and Theodor Boveri develop the
    theory of chromosomal inheritance
  • 1910 Thomas Morgan verifies chromosomal using
    fruit flies
  • 1928 Fredrick Griffith studies genetics in mice
  • 1944 Oswald Avery indicates DNA is genetic
    material

4
History part 2
  • 1952 Maurice Wilkins and Rosalind Franklin
    photograph DNA
  • 1952 Alfred Hershey and Martha Chase confirm DNA
    as genetic material
  • 1953 James Watson and Francis Crick model DNA

5
So?
  • The big names to know (and what theyre known
    for)
  • Mendel
  • Wilkins and Franklin
  • Hershey and Chase
  • Watson and Crick

6
DNA structure
  • DNA is made of nucleotides
  • Made of 3 components
  • A 5-carbon sugar (deoxyribose)
  • A phosphate group
  • A nitrogen base (4 options)

7
The 4 bases
  • Adenine (A)
  • Guanine (G)
  • Cytosine (C)
  • Thymine (T)
  • Adenine and Guanine are Purines
  • Cytosine and Thymine are Pyrimidines

8
The twisted ladder
  • Soon after Wilkins and Franklin took a snapshot
    of DNA, Watson and Crick realized it was far too
    thick to be a single strand.
  • Watson and Crick modeled DNA as a double helix,
    two strands wound around each other.

9
DNA Structure
  • Known also as a twisted ladder due to its
    appearance.
  • Each rung/step is the matching of a purine to a
    pyrimidine
  • The backbone is made of the carbon and phosphate
    regions of the nucleotides
  • AT form 2 hydrogen bonds
  • GC form 3 hydrogen bonds

10
Replication
  • DNA replication occurs in much the same way as
    unzipping a zipper.
  • Enzymes split the DNA into 2 strands
  • Free-floating nucleotides bind to their
    complementary base
  • Backbones form on the new side
  • Replication happens in opposite directions on
    each strand (imagine the left side forms
    travelling up, while the right side forms
    travelling down)

11
Check Questions
  • What are the 3 common parts of a nucleotide?
  • What are the 4 nitrogen bases?
  • Are there always an equal number of cytosine to
    guanine?

12
Science Fair Details
  • What goes in your ½ in to 1 in binder
  • Research Paper (updated if necessary)
  • Experimental Design
  • Question
  • Purpose
  • Hypothesis
  • Materials
  • Procedure
  • Graphs and Data Tables
  • Data Analysis
  • What does the data show? Interpret your data
  • Conclusion
  • How do your findings relate to your hypothesis?
  • What errors did you have in your experiment?
  • How could you expand on your project?
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