When DNA Changes – Chap. 17

1. When DNA Changes – Chap. 17 http://www.rottentomatoes.com/m/xmen/trailers.php Left: A normal fruit fly (drosophila). Middle: A fruit fly with its legs jutting from its head; a mutation induced by radiation. Right: A disastrous effect of mutations on the human body. The boy is a Chernobyl nuclear plant accident victim.

2. DNA is stable

3. Frequency of Mutations

4. DNA Damage Mutagens are agents that cause mutations – a failure to repair DNA

5. Three levels of mutational change Level 1. Point or Single-Base Mutations • 3 Types: I. (Base) Substitutions or Missense Mutation (Fig. 17.5 in text)Threeoutcomes • Silent mutations –

6. Neutral mutations – • “Drastic” mutations NOVA. One Wrong Letter

7. II. Chain-Termination Mutations III.Frameshift Mutations

8. Level 2. Chromosomal Mutations

9. 3 Types: • Deletions – entire sections of the chromosome are left out • Inversions – a middle fragment may flip over and then rejoin

11. Translocations – two nonhomologous • chromosomes break, swap segments, and fuse • together (ex. human #9 and #22 resulting in a type • of lukemia)

12. Level 3. Transpositions