1. 1 Chapter 9 DNA the Genetic Material

2. 2 Transformation-Griffith Griffith discovery about transformation occurred by accident. Griffith’s transformation experiments caused harmless bacteria to become deadly Griffith’s experiment showed that genetic material could be transferred between dead bacteria and living bacteria.

3. 3 Transformation (pp 191) Transformation- change in genotype caused by when cells take up foreign genetic material. Vaccine: a harmless version of a disease-causing microbe Virulent- able to cause disease

4. 4 Avery’s Experiment Avery’s experiment showed that transformation could be prevented by DNA-destroying enzymes. Avery and his research team concluded that DNA was the genetic material

5. 5 Viral Genes & DNA Hershey and Chase settled the controversy over DNA being the genetic material of life. Using radioactive tracers Hershey and Chase demonstrated without question that DNA is the molecule that stores genetic information in cells

6. 6 Bacteriophage – a virus that infects bacteria (bacteria eater)

7. 7 The Structure of DNA Watson and Crick – determined that DNA molecules have the shape of a double helix (twisted ladder) Watson/Crick- credited with establishing the structure of DNA DNA molecules are composed genes which are in turn composed of long chains of nucleotides

8. 8 DNA nucleotides DNA nucleotides are composed of three parts: Five carbon sugar – dexoyribose Phosphate Nitrogen base

9. 9 DNA DNA is named for its five carbon sugar deoxyribose Four possible nitrogen bases in DNA Adenine Thymine Guanine Cytosine

10. 10 DNA Bases The four bases make up two groups called purines and pyrimidines. Purines and pyrimidines are classification groups for nitrogen bases The bases always pair in the following order: Adenine – Thymine Guanine – Cytosine Amount of adenine always equals the amount of thymine Amount of guanine always equals the amount of cytosine

11. 11 Complementary base pairs Complementary bases are opposite base pairs according to the base-pairing rules. Complementary bases are formed at DNA replication Replication-is the process by which DNA copies itself The strands of a DNA molecule are held together by hydrogen bonding between adenine-thymine and cytosine-guanine

12. 12 During DNA replication, a complementary strand of DNA is made for each original DNA strand. Thus, if a portion of the original strand is CCTAGCT, then the new strand will be GGATCGA After replication, the nucleotide sequences in both DNA are identical to each other and to the original DNA molecule