Mutations

1. Mutations

2. Defined: one nucleotide is substituted for another Often repaired by spellchecker enzyme May lead to amino acid change See animation May not lead to any change (Silent Mutation) Ex: DNA “CCC” is mutated into “CCG” Same amino acid is created (glycine) Gene: Point Mutations T A C A G T G G T C A A A DNA U G U C A C A C A G U U U mRNA cysteine glutamine histidine glutamine phenylalanine Amino acids

3. Gene: Frame Shift Mutation C A C A G T G G T C A A A DNA • Defined: insertion/deletion of a nucleotide • Entire sequence of DNA/RNA after the mutation is shifted (see animation) • Much more serious to the final protein G U G U C A C C A G U U U mRNA cysteine histidine glutamine phenylalanine Amino acids histidine serine leucine

4. Gene: Frame Shift Mutation C A C A G T G G T C A A A DNA U G U C A C C A G U U U G mRNA histidine glutamine phenylalanine cysteine Amino acids glutamine proline valine

5. Impact on Offspring • Somatic cell mutations • Affect only the individual • Not passed on to future generations • Ex: Muscle cell mutation • Germ cell mutations • Germ cells create egg and sperm by meiosis • May be passed to future generations

6. Mutation Causes • Mutagen: agents in the environment that can change DNA • Speed up replication process • Break apart nucleotides • Ex: UV sunlight breaks hydrogen bond between thymine (T) and adenine (A)

7. Kobe Kuiz • How are proteins affected if the DNA code is mutated? Example: ATTCGAGG is mutated to ATTCGTGG • What is the difference between a point mutation and frame shift mutations? • When are mutations passed on to future generations? • What is a mutagen and how do they cause problems?