Mutations

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)

Gene: Frame Shift Mutation C 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”

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

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)