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Mutations. Causes of Mutations. Random error in DNA replication or DNA proofreading mechanisms UV radiation Some chemicals. Types of Mutations. Substitutions/Point Mutations One nucleotide switched Additions/Deletions Inversions DNA gets rearranged. THE FAT CAT ATE THE DOG.
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Causes of Mutations • Random error in DNA replication or DNA proofreading mechanisms • UV radiation • Some chemicals
Types of Mutations • Substitutions/Point Mutations • One nucleotide switched • Additions/Deletions • Inversions • DNA gets rearranged
THE FAT CAT ATE THE DOG • Minor substitution/silent mutation: • THE FAT CAT ATE THA DOG • Major substitution: • THE FAT CAT ATE THE HOG • Addition: • THE GFA TCA TAT ETH EHO G • Deletion: • THF ATC ATA TET HEH OG • Inversion: • THE FAT DOG ATE THE CAT or THE FAH EDT CAT ATE TOG
Point Mutations • Can be silent since sometimes multiple codons code for the same amino acid • Can have a minor affect on protein shape/function • Can have a major effect on protein shape/function
Non-sense Point Mutations • Protein is completely altered due to a single substitution in…. • The start or stop codon!
Frameshift Mutations • Additions/deletions change the reading frame • Whole protein is altered and usually destroyed • E.g. Tay-Sachs
Mutations • Usually neutral (99% of DNA is non-coding) • If they have an effect, usually bad • Very, very rarely the mutation might be beneficial • Source of diversity
How Can Mutations Be Beneficial? • New proteins accomplish a new task • Gene duplication • Genes get copied • One copy is “free” to mutate without harming the organism • Allows possibility of new helpful protein and old necessary protein to both be produced