1. DNA: The Genetic Material
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

2. Hammerling Experiment
Cells of green algae cut into pieces and observed to see which were able to express heredity information.
Discovered heredity information stored in the foot of the cell.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

3. Transplantation Experiments
Very early it was discovered chromosomes were composed of proteins and DNA. But it took several experiments to conclusively determine specifically which substance made up genes.
Griffith Experiment
Documented movement of genes from one organism to another (transformation).
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

4. Avery and Hershey-Chase Experiments
Avery Experiment
Removed almost all protein from bacteria, and found no reduction in transforming activity.
Hershey-Chase
Used radioactive isotopes to label DNA and protein. Found genes used to specify new generations of viruses were made of DNA.

5. Chemical Nature of Nucleic Acids
DNA made up of nucleic acids.
Five carbon sugar, phosphate group, and an organic base.
Purines - Large bases
Adenine and Guanine
Pyrimidines - Small bases
Cytosine and Thymine
Chargaff’s Rule
A =T and G=C
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

6. Fig. 14.7

7. Chemical Nature of Nucleic Acids
Nucleotide made up of a sugar attached to a phosphate and a base.
Nucleotides distinguished by the bases.
Reaction between phosphate group of one nucleotide and hydroxl group of another is dehydration synthesis.
Phosphodiester Bond
3-5 phosphodiester bond
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

8. Three-Dimensional Structure of DNA
X-ray diffraction suggested DNA had helical shape with a diameter of about 2 nanometers.
Watson and Crick deduced DNA is a double helix with bases of two strands pointing inward forming base-pairs.
Purines pairing with pyrimidines.
Constant 2 nanometer diameter.
Strands are antiparallel.

9. Raven - Johnson - Biology: 6th Ed
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

10. Semi-Conservative Replication
Each chain in the helix is a complimentary mirror image of the other.
Double helix unzips and undergoes semi-conservative replication.
Each strand of the original duplex becomes one strand of another duplex.
Confirmed by Meselson-Stahl Experiment.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

11. Replication Process
Replication of DNA begins at one or more sites on the DNA molecule where there is a specific sequence of nucleotides called a replication origin.
DNA replicating enzyme DNA polymerase III and other enzymes add nucleotides to the growing complementary DNA strands.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

12. Raven - Johnson - Biology: 6th Ed
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

13. Fig

14. RNA polymerase (primase) constructs an RNA primer.
Replication Process
DNA polymerase cannot link the first nucleotides in a newly synthesized strand.
RNA polymerase (primase) constructs an RNA primer.
DNA polymerase adds nucleotides to 3’ end.
Leading strand replicates toward replication fork.
Lagging strand elongates from replication fork.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

15. DNA Replication Fork
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

16. DNA ligase attaches fragment to lagging strand.
Replication Process
DNA ligase attaches fragment to lagging strand.
Because synthesis of the leading strand is continuous, while the lagging strand is discontinuous, the overall replication of DNA is referred to as semidiscontinuous.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

17. Opening DNA Double Helix Initiating replication Unwinding duplex
Replication Process
Opening DNA Double Helix
Initiating replication
Unwinding duplex
Stabilizing single strands
Relieving torque
Building a Primer
Assembling Complementary Strands
Removing the Primer
Joining Okazaki Fragments
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

18. Eukaryotic Replication
In Eukaryotic cells, DNA is packaged in nucleosomes within chromosomes.
Each individual zone replicates as a discrete section called a replication unit or a replicon.
Each replication unit has its own origin of replication.
Fast Replication
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

19. One-Gene/One-Polypeptide Hypothesis
Genes produce their effects by specifying the structure of enzymes.
Each gene encodes the structure of one enzyme.
Many enzymes contain multiple polypeptide subunits, each encoded by a separate gene.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

20. Pivotal Genetic Experiments Chemical Nature of Nucleic Acids
Review
Pivotal Genetic Experiments
Chemical Nature of Nucleic Acids
Three-Dimensional Structure of DNA
Replication
Semi Conservative
Eukaryotic DNA Replication
One-Gene/One-Polypeptide Hypothesis
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

21. Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies