Molecular Biology I. Introduction A. History 1. A. Meischer (1868) band rich in acid-phosphates 2. F. Griffith (1928) protein not inherited molecule

3. S. Luria, M. Delbruk, A. Hershey and M. Chase (1952) Viruses Figure 10.1A Figure 10.1C 4. E. Chagraff (1952) T=A and G=C (in DNA pairing)

6. J. Watson & F. Crick (1953) built a model of DNA 5. R. Franklin (1952) uniform diameter, helical shape, highly repeatable Figure 10.3B Figure 10.3A

II. DNA Replication A. Definition B. Rules 1. DNA Orientation  5’ to 3’ Figure 10.2A Figure 10.3D

2. Directional  Read 3’ to 5” lay down 5’ to 3’ Figure 10.4A 3. Semi-conservative Replication (M. Meselson & F. Stahl)

C. Process by Players 1. DNA Helicase (opens DNA) 2. RNA Primase (lays down a short RNA sequence primer to direct the next enzyme) Figure 10.5C Figure 10.5A

3. DNA Polymerase III (read 3’ end of primer to lay down DNA bases opposite the original strand) 4. DNA Polymerase I (removes primer and lays down DNA bases)

5. DNA Ligase (ties together all the loose ends)

D. Editing & Repair 1. Players and Process a. Editing = DNA polymerase I & DNA Ligase b. Repair = DNA nuclease, DNA polymerase I, & DNA ligase

E. Maintaining Length 1. Problem 2. Players a. Lengthen = DNA telomerase, DNA polymerase I, & DNA ligase