1. Genetic Mutations

3. Mutation: An unpredictable change in the genetic material of an organism Gene Mutation: A change in the structure of a DNA molecule, producing a different allele of a gene (allele = version of a gene; ex: brown hair, black hair) Chromosome Mutation: A change in the entire structure or number of whole chromosomes

4. Causes of Mutations Mutations occur randomly with no obvious cause. Mutagens: Substances that increase the chances of mutation occurring

5. Types of Mutations Base Substitution – One nucleotide base takes the place of another

6. One amino acid is changed in the sequence

7. Base Substitutions Missense = if substitution changes amino acid Nonsence = if substitution changes amino acid into a “stop” codon

8. Types of Mutations Base Addition – (aka Insertions) One or more extra nucleotide bases added to a sequence Base Deletion – One or more nucleotide bases are lost from the sequence **Both additions and deletions cause Frame Shift Mutations

9. Incorrect sequence of amino acids

10. Frame Shift Mutations

12. Silent mutations – Mutation that has no apparent effect on an organism OR does not change the amino acid

13. Which types of mutations have the greatest impacts?

14. Sickle Cell Anemia

15. Base substitution with a significant side effect on phenotype The affected gene codes for the oxygen carrying pigment HAEMOGLOBIN. Normal Amino Acid Sequence: Val-His-Leu-Thr-Pro-Glu-Glu-Lys- Sickle Cell Anemia Sequence: Val Val-His-Leu-Thr-Pro-Val-Glu-Lys-

16. When haemoglobin is not combined with oxygen, the β chains are less soluble causing them to stick to each other. This pulls RBC’s out of shape into a sickle shape.

17. Phenylketonuria (PKU) Base substitution The affected gene codes for an enzyme (phenylalanine hydroxylase), which is not present in people with the mutation This enzyme helps catalyse the conversion of phenylalanine to triosine, which is then converted to melanine

18. Effects of PKU Lighter skin colour Accumulation of phenylalanine in blood and tissue fluid, causing severe brain damage Babies are tested for PKU at birth for prevention

19. Environmental Impacts on Phenotype Some alleles code for traits that are highly impacted by environmental factors, such as height. Diet Temperatures