1. Mutations

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

3. Gene: Frame Shift MutationC A G T G G T C A A A C
DNA U G U C A C C A G U U U G
mRNA
Amino acids
cysteine
histidine
histidine
glutamine
serine
phenylalanine
leucine
Defined: insertion/deletion of a nucleotide
Entire sequence of DNA/RNA after the mutation is shifted (see animation)
Much more serious to the structure/function of the final protein
mRNA sequence may have early or late “stop codons”

5. Impact on Offspring Somatic cell mutations Affect only the individual
Not passed on to future generations
Ex: Muscle cell mutation
Germ cell mutations
May be passed to future generations
Ex: Sperm cell mutation

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)