2. MUTATIONS

3. Mutations Defined: a change in an organism’s DNA. Many kinds of mutations can occur, especially during replication. 2 Types: 1)Gene Mutations: – A point mutation, substitutes one nucleotide for another. mutated base

4. Gene: Point Mutations May lead to amino acid change – See animation May not lead to any change (called “Silent Point Mutation”) – Ex: DNA “CCC” is mutated into “CCG” » Same amino acid is created (glycine) DNA mRNA Amino acids

5. –A frameshift mutation (another type of gene mutation) inserts or deletes a nucleotide in the DNA sequence.

6. Gene: Frame Shift Mutation Entire sequence of DNA/RNA after the mutation is shifted (see animation) Much more serious to the structure/function of the final protein – mRNA sequence may have early or late “stop codons” DNA mRNA Amino acids

7. What type of mutation would this be? Original: The fat cat ate the wee rat. Mutation: The fat hat ate the wee rat.

8. What about this one? Original: The fat cat ate the wee rat. Mutation: The fat caa tet hew eer at. Which has a much large effect on the end result? Point or frameshift mutation?

9. affect many genes. –Gene duplication results from unequal crossing over. Chromosomal mutations may occur during crossing over 2) Chromosomal Mutations

10. Translocation results from the exchange of DNA segments between nonhomologous chromosomes.

11. Mutations may or may not affect phenotype. Chromosomal mutations tend to have a big effect. Some gene mutations change phenotype. – A mutation may cause a premature stop codon. – A mutation may change protein shape or the active site. – A mutation may change gene regulation. blockage no blockage Ex: Cysitc Fibrosis (mutation causes excess mucus build up in airways)

12. Some gene mutations do not affect phenotype. –A mutation may be silent. –A mutation may occur in a noncoding region. –A mutation may not affect protein folding or the active site.

13. Impact on Offspring Somatic Cells (body) Only affect the individual Not passed to offspring Ex: muscle cell mutation Germ Cells (sex) May be passed to offspring Mutations in sex cells can be harmful or beneficial to offspring. In nature, these are often removed from a population (natural selection)- as these don’t usually survive.

14. Causes of Mutations Replication errors can cause mutations. Mutagens, such as UV ray and chemicals, can cause mutations. Some cancer drugs use mutagenic properties to kill cancer cells.