1. DNA
The code of life

2. 1. Structure of DNA DNA is described as a twisted ladder
DNA is made up of
Nitrogen Bases (rungs of
the ladder)
Phosphate and Sugar “backbone”
Nitrogen Bases
Nitrogen is an element of
life! (Remember CHON?)
There are 4 Bases:
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

3. 2. Base Pairing
Like a puzzle, only certain nitrogen bases pair with one another.
Adenine pairs with
Thymine
Cytosine pairs with
Guanine
A-T and C-G

4. Some DNA History – Friedrich Meischer
The first person to isolate DNA
Worked with White Blood Cells
White blood cells are cells that fight invaders in your body

5. Some DNA History - Chargaff
Isolated DNA from different organisms
Measured the amounts of the four bases (adenine, thymine, cytosine, and guanine)
He found that the amount of adenine = thymine and cytosine = guanine!
Therefore,
A pairs with T and
C pairs with G!

6. Some DNA History – Rosalind Franklin
British BioPhysicist
Made great
contributions to the
understanding of DNA
Her X-Ray diffraction
images of DNA led to the
discovery of the DNA
double helix
Died at 37 from
complications of ovarian
cancer

7. DNA History – Watson and Crick
Franklin’s DNA photographs helped Watson and Crick figure out the structure of DNA in 1953
Were awarded the nobel
prize in 1962

8. 3. DNA Replication To replicate means “to make a copy”
During interphase, the DNA is copied to prepare itself for cell division
The copy made is the exact same DNA as the parent DNA.

9. DNA Replication – The Process
The DNA molecule “unzips” between the paired bases
New bases that float around in the nucleus are added to the old strand
Each new DNA molecule exactly matches the order in the original!
What do you think would happen if there were mistakes made during DNA replication? (for example, wrong base pairs were added?)

10. Replication to Protein
Spg

13. DNA Structure Discovery http://www.youtube.com/watch?v=sf0YX nAFBs8
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DNA Structure