12.1 DNA and RNA

Basic DNA Information What does DNA stand for? Deoxyribonucleic Acid Where is DNA found? In the nucleus of our cells What does DNA do for us? Stores and transmits genetic info Where does our DNA come from? Half from our mom and half from our dad

Rosalind Franklin X Ray diffraction Shaped is twisted Contain two strands

Watson and Crick Model

Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone Section 12-1 Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

DNA Nucleotides Purines Pyrimidines Section 12-1 Phosphate group Adenine Guanine Cytosine Thymine Phosphate group Deoxyribose

Chargaff’s Rule – Base Pairing Rule Source of DNA A T G C Streptococcus 29.8 31.6 20.5 18.0 Yeast 31.3 32.9 18.7 17.1 Herring 27.8 27.5 22.2 22.6 Human 30.9 29.4 19.9 19.8 % of A ≈ % of T % of G ≈ % of C

Chromosome Structure of Eukaryotes Section 12-2 Human cells contain over one meter of DNA! How? Human DNA has about 3 billion base pairs Nucleosome Chromosome DNA double helix Coils Supercoils Histones Wrapped around proteins (histones and nucleosomes)

DNA Replication Section 12-2 Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork Nitrogenous bases New strand Original strand

http://www.wwnorton.com/college/biology/discoverbio3/full/content/ch12/animations.asp http://www.youtube.com/watch?v=zdDkiRw1PdU&feature=related

DNA replication

How DNA is packaged

Chromosome Structure of Eukaryotes Section 12-2 Human cells contain over one meter and around 3 billion base pairs long of DNA! How? Nucleosome Chromosome DNA double helix Coils Supercoils Histones Wrapped around proteins (histones and nucleosomes)