1. 2007-2008 AP Biology Chapter 17 Mutations: Point, Frameshift and Examples

2. AP Biology When do mutations affect the next generation? Mutations Point mutations  single base change  base-pair substitution silent mutation  no amino acid change  redundancy in code (wobble effect) missense  change amino acid nonsense  change to stop codon

3. AP Biology Point mutation leads to Sickle cell anemia What kind of mutation? Missense!

4. AP Biology Sickle cell anemia Primarily African Population  recessive inheritance pattern  strikes 1 out of 400 African Americans Link to Animation Link to Discussion on abnormal fiber formation (valine hydroph.) Link to Discussion on abnormal fiber formation (valine hydroph.

5. AP Biology Mutations Frameshift  shift in the reading frame changes everything “downstream”  insertions adding base(s)  deletions losing base(s) Where would this mutation cause the most change: beginning or end of gene?

6. AP Biology Cystic fibrosis Primarily caucasions of European descent  strikes 1 in 2500 births 1 in 25 whites is a carrier (Aa)  normal allele codes for a membrane protein that transports Cl - across cell membrane defective or absent channels limit transport of Cl - (& H 2 O) across cell membrane thicker & stickier mucus coats around cells mucus build-up in the pancreas, lungs, digestive tract & causes bacterial infections  without treatment children die before 5; with treatment can live past their late 20s  Quick intensive animation (must see) Quick intensive animation (must see)  Link to Animated Discussion Link to Animated Discussion

7. AP Biology Effect on Lungs Chloride channel transports chloride through protein channel out of cell Osmotic effects: H 2 O follows Cl - airway Cl - H2OH2O H2OH2O mucus secreting glands bacteria & mucus build up thickened mucus hard to secrete normal lungscystic fibrosis cells lining lungs Cl - channel

8. AP Biology Notice that after CTT is removed, the AT T joins and still makes the same amino acid (ATC and ATT both are DNA codons for isoleucine, but the PHE is omitted) example of Silent Mutation PLUS DELETION.

9. 2007-2008 AP Biology What’s the value of mutations?

10. Example of Different expressions of codon tables: May have DNA, mRNA or tRNA codons DNA codons, coding strand, 5’ - 3‘ mRNA codons, 5’ - 3‘

11. AP Biology Point mutation leads to Sickle cell anemia What kind of mutation?