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?