Definitions

Mutation – any change in the genetic sequence. Gene alteration – when a change in

the genetic code changes the amino acid sequence

Silent mutation- when a change in the genetic code doesn’t change the amino acid sequence

Kinds of mutations

Point mutation – change in just one nucleotide AAA mutates to AAGInsertion mutation – change in sequence by adding one or more bases.Deletion mutation – change in sequence by taking out one or more bases.Frame shift mutation – the result of an insertion or deletion that moves the codons down and changes all the amino acids

Frame shift mutation example

AAG TAG CAT ACTAAT AGC ATA CT_

Mutation Worksheet #1Original DNA: AGA GCA CTT AAA AGG

Amino Acid sequence SER-ARG-GLU-PHE-SER

Mutated sequence: AGA GCG CTT AAA AGG

Amino Acid sequence: SER-ARG-GLU-PHE-SER

Type of mutation: Point mutationGene alteration: None

Mutation Worksheet #2Original DNA: AGA GCA CTT AAA AGG

Amino Acid sequence SER-ARG-GLU-PHE-SER

Mutated sequence: AGA GCA CTT AAT AGG

Amino Acid sequence: SER-ARG-GLU-LEU-SER

Type of mutation: Point mutationGene alteration: yes, but only one a.a.

Mutation Worksheet #3Original DNA: AGA GCA CTT AAA AGG

Amino Acid sequence SER-ARG-GLU-PHE-SER

Mutated sequence: AGA CAC TTA AAA GG

Amino Acid sequence: SER-VAL-ASP-PHE-___

Type of mutation: deletion; frame shiftGene alteration: yes, frame-shift

Mutation Worksheet #4Original DNA: AGA GCA CTT AAA AGG

Amino Acid sequence SER-ARG-GLU-PHE-SER

Mutated sequence: AGA GCA ATC CCG TTC GGG CTT AAA

AGG

Amino Acid sequence: SER-ARG-STOP

Type of mutation: insertionGene alteration: yes, significant

Mutation Worksheet #5Original DNA: AGA GCA CTT AAA AGG

Amino Acid sequence SER-ARG-GLU-PHE-SER

Mutated sequence: AGA GCA AAA AGG

Amino Acid sequence: SER-ARG-PHE-SER

Type of mutation: deletionGene alteration: yes, missing an a.a.

6. When a point mutation results in the same amino acid sequence, is it still considered a mutation?

Yes because a mutation is a change in the genetic code and it may or may not result in a change in the amino acid sequence. A mutation that doesn’t result in a change in the amino acid sequence is called a silent mutation