I. History of DNA A. Friedrich Miescher 1. Identified DNA in the nucleus of white blood cells in 1871 2. It was a sugary, phosphate-rich chemical which he called nuclein

B. Fredrick Griffith- The Transformation Experiment- 1928 1. British bacteriologist whose focus was on the epidemiology and pathology of bacterial pneumonia 2. His experimentation is now known as the transformation experiment 3. He showed that Streptococcus pneumoniae, could transform from one strain into a different strain 4. The transforming principle was later identified as DNA

C. Oswald Avery- DNA is the Genetic Material- 1944

1. The genetic information was thought to be contained in protein 2. Continuing the research done by Griffith in 1928, Avery worked with MacLeod and McCarty on the mystery of the transformation 3. His team made protein and DNA extracts of the capsulted strain (which has a smooth surface) and introduced the substance into a rough-surfaced type of bacterium 4. The rough-surfaced strain transformed into the smooth-surfaced type, he knew the substance he had extracted contained the gene that coded for the smooth surface 5. Avery published the results of his research in 1944. The paper led to more intensive studies of DNA, which eventually revealed it to be the common agent of heredity

D. Alfred Hershey and Martha Chase 1. “Waring Blender” Experiment 2. DNA is the Genetic Material- 1952

Food Blender Centrifuge

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DNA P Labeled Protein S Labeled

E. Erwin Chargaff – 1940’s 1. Chargaff's rules a. The amount of guanine is equal to cytosine and the amount of adenine is equal to thymine

b. The composition of DNA varies from one species to another, in particular in the relative amounts of A, G, T, and C bases

F. Discovery of the Structure of DNA 1. James Watson and Francis Crick- 1953 a. Cambridge University 2. Maurice Wilkins and Rosalind Franklin a. Kings College

Photo 51

The Watson and Crick Model of the Structure of DNA

II. DNA Structure A. Double Helix

B. DNA NucleotideC. Base Pairing

D. Purine and Pyrimidine BasesE. Antiparallel Nature of DNA

F. DNA Replication

G. Messelson and Stahl 1. DNA Replicates Semi-conservatively 2. Let E. coli replicate its DNA in Nitrogen- 15 for several generations

III. RNA Characteristics A. RNA Nucleotide

B. Types of RNA 1. Messenger RNA 2. Transfer RNA 3. Ribosomal RNA C. Transcription

D. RNA Processing in Eukaryotes

E. The Genetic Code: mRNA codons

IV. Translation of the Genetic Code A. Protein Synthesis

Polysomes

V. Mutations to the DNA Molecule

Missense

Nonsense

Frameshift Mutation

VI. The Operon Model of Gene Expression A. The Lac Operon