DNA and the CENTRAL DOGMA Everything you never wanted to know, but still need to understand… and then some more bonus stuff to really make you happy

Transformation of Bacteria a) Mouse dies b) Mouse lives c) Mouse lives d) Mouse dies. Living S cells are found in blood sample from dead mouse 1928 Fredrick Griffith

Phages are viruses that infect bacteria (bacteriophage)

3. Centrifuge and measure radioactivity 1. Mix phages with bacteria 2. Blend to mix

What makes up DNA subunits? 5-carbon sugar Phosphate Nitrogenous base

A and G are Purines (double rings) C and T are pyrimidines (single rings) “Attorney Generals are pure”

DNA REPLICATION DNA polymerase attaches nucleotides to each template strand 2 complimentary strands. A=T C≡G Helicase breaks H bonds and unzips Each “daughter” DNA consists of one parental and one new strand

Conservative – parental helix remains intact; an all new copy is made SemiConservative – two strands separate and each functions as a template Dispersive – each strand contains pieces of old and new DNA

Meselson-Stahl Experiment 1st replication ~20 min 2nd replication ~40 min “new” DNA synthesized would be lighter than the “old” DNA Incorporates heavy nitrogen into DNA Incorporates lighter nitrogen into DNA

EUKARYOTES: many origins of replication

Incorporation of nucleotide Enzyme DNA polymerase catalyzes this reaction

5’3’ direction of one strand runs counter to the other

DNA Helicase – unzips Topoisomerase – unwind DNA SSBP – single strand binding proteins, hold strands open Primase – joins RNA nucleotides to eukaryotes (primer is required for polymerase to synthesize) DNA Polymerase – adds nucleotides Ligase – link Okazaki fragments

New DNA

Excision repair of DNA

FROM GENE TO PROTEIN Beadle and Tatum – one gene, one polypeptide