Agenda

Songs?

Go over transcription/translation jokes simulation

Mutations

Practice Quiz / Review time

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

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 MutationsCan 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

MutationsUsually 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 duplicationGenes get copiedOne copy is “free” to mutate without harming the organismAllows possibility of new helpful protein and old necessary protein to both be produced