DNA The code of life

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)

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

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 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!

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

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 division The copy made is the exact same DNA as the parent DNA.

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?)

Replication to Protein http://www.youtube.com/watch?v=1fiJupfb Spg

DNA Structure Discovery http://www.youtube.com/watch?v=sf0YX nAFBs8 http://www.youtube.com/watch?v=qy8dk 5iS1f0 DNA Structure