1. Chromosomes & DNA Replication

2. Important Scientist: Griffith
Injected mice with four different pneumonia bacteria samples.
disease causing = dies
harmless = lives
heat killed disease causing = lives
heat killed disease causing + harmless = dies
Some factor from the dead bacteria had “transformed” the harmless bacteria into a disease causing one.
Transformation – transferring genetic information from one bacterium to another.

3. Griffith

4. Avery
repeated Griffith’s experiment but used enzymes to break down the substance used in the transformation.
Nucleic acid DNA stores & transmits genetic information.

5. Hershey & Chase
Bacteriophages – virus that infects bacteria. Made of a DNA or RNA core and a protein coat.
Wanted to know if the DNA or the protein coat entered the bacteria.
Grew viruses containing radioactive isotopes.
DNA was the genetic material.

6. Hershey & Chase

7. Cell Types Prokaryotes Eukaryotes DNA: cytoplasm
a single circular DNA molecule or chromosome
Eukaryotes
1000x DNA as prokaryotes
DNA: nucleus
several chromosomes

8. DNA Replication
Strands are complementary because each strand can be used to make the other strand.

9. How DNA is Replicated
Replication Fork: DNA molecule separates into two strands
Each DNA strand serves as a template for the new strands
Follow base pairing rule
DNA polymerase: enzyme
joins nucleotides
proofreads each “new” DNA strand