DNAThe code of life

1. Structure of DNADNA is described as a twisted ladderDNA 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)

2. Base Pairing

Like a puzzle, only certain nitrogen bases pair with one another.

Adenine pairs with ThymineCytosine pairs with Guanine

A-T and C-G

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

Some DNA History - Chargaff

Isolated DNA from different organismsMeasured 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!

Some DNA History – Rosalind FranklinBritish BioPhysicistMade great contributions to the understanding of DNAHer X-Ray diffraction images of DNA led to the discovery of the DNA double helixDied at 37 from complications of ovarian cancer

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

3. DNA Replication

To replicate means “to make a copy” During interphase, the DNA is copied to

prepare itself for cell divisionThe copy made is the exact same DNA as

the parent DNA.

DNA Replication – The Process

1. The DNA molecule “unzips” between the paired bases

2. New bases that float around in the nucleus are added to the old strand

3. 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?)

Replication to Protein

http://www.youtube.com/watch?v=1fiJupfbSpg

DNA Structure

Discoveryhttp://www.youtube.com/watch?v=sf0YXn

AFBs8Structurehttp://www.youtube.com/watch?v=qy8dk5

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