DNA and DNA Replication Chapter 12 – Part 1 CP Biology Paul VI Catholic High School

12-1 DNA I.HISTORICAL BACKGROUND 1. Hammerling Experiment: Joachim Hammerling 1930’s Acetabularia mediterranea Acetabularia crenulata Hammerling Experiment video clip

12-1 DNA

2. Frederick Griffith (1928) Streptococcus pneumonia Smooth-pathogenic Rough-non-pathogenic Transforming Factor I.Historical Background: 12-1 DNA Griffith experiment video clip

12-1 DNA

I.HISTORICAL BACKGROUND: 3. Oswald Avery (1944): Revisited Griffith’s experiment Utilized “digesting” enzymes Localized “Transforming Factor” to DNA 12-1 DNA

Oswald Avery DNA

I. Historical Background: 4. Hershey-Chase (1952) Utilized T 2 Bacteriophages DNA containing viruses Used radioisotopes 32 P and 35 S Corroborated work of Avery 12-1 DNA Hershey-Chase experiment video clip

Alfred Hershey Martha Chase 12-1 DNA

T 2 Bacteriophage 12-1 DNA

Phoebus Levene 12-1 DNA

II. Chemistry of DNA: 1. Phoebus Levene (1920’s) a. DNA composed of: PO 4 5 Carbon Sugar (deoxyribose) Nitrogen containing base Purine (adenine, guanine) “double ringed” base Pyrimidine (cytosine, thymine) “single-ringed” base 12-1 DNA

adenine guanine cytosinethymine 12-1 DNA

Nucleotide 12-1 DNA

Phosphodiester Bond 12-1 DNA

II. Chemistry of DNA: 1. Phoebus Levene: b. NUCLEOTIDES are the monomers of the DNA molecule c. DNA has intrinsic directionality One end ALWAYS has 5’PO 4 One end ALWAYS has 3’OH 12-1 DNA

Erwin Chargaff 12-1 DNA

II. Chemistry of DNA: 2. Erwin Chargaff CHARGAFF’S RULE: Amount of adenine is ALWAYS equal to amount of thymine Amount of cytosine is ALWAYS equal to amount of guanine 12-1 DNA Short HHMI video clip

Chargaff’s Rule 12-1 DNA

III. Structure of DNA: A. Contribution of 1. James Watson & Francis Crick 2. Maurice Wilkins 3. Rosalind Franklin B. Double Helix Model 1. Antiparallel Strands 2. Complementarity of bases bp per turn of helix 12-1 DNA

James Watson Francis Crick 12-1 DNA Secrets of the Sequence video clip

Rosalind Franklin Maurice Wilkins 12-1 DNA

Diffraction Study 1952 Diffraction Study DNA

X-Ray study DNA DNA

DOUBLE HELIX 12-1 DNA

10 bp per turn 3.4 nm per turn 3.4Å between bp 1Å = 0.1nm (1X m) 12-1 DNA

Antiparallel arrangement of helices 12-1 DNA

Complement Base Pairing A pairs with T G pairs with C 12-1 DNA

12- 2 DNA Replication

IV. Replication Process Summary: A. Opening the Double Helix B. Building the Primer C. Assembling Complementary Strands D. Removing the Primer E. Joining of Okazaki Fragments DNA Replication Video and DNA Replication Worksheet

IV. Replication Process: A. Opening the Double Helix: 1. Initiating Replication Replication origin 2. Unwinding the Duplex Helicase 3. Stabilizing Complementary Strand Single Strand Binding Protein 4. Relieving the torque Topoisomerase (“swivelase”) DNA Replication

Helicase unwinds the double strand DNA Replication

Topoisomerase I and II Topoisomerase I and II video

Topoisomerases relieve the torque generated by the unwinding of the helix DNA Replication

Direction of synthesis Building the primer DNA Replication

RNA Polymerase (Primase) DNA Replication

B. Building the Primer: RNA Polymerase (Primase) “Primasome” C. Assembling the Complementary Strands DNA Polymerase III D. Removing the Primer DNA Polymerase II (Rnase H) E. Joining Okazaki Fragments DNA Ligase DNA Replication

Removal of RNA primer By RNAse H DNA Replication

Synthesis of Lagging Strand DNA Replication

Part 1 – DNA’s Discovery video clip DNA – The Secret of Photo 51 (NOVA video 55 min)