Mutations

Gene Mutation Gene mutation is a change in base code sequence Errors in replication Rare DNA polymerase & repair enzymes “proof reads” new strands Mutagens Environmental influences Radiation, UV light, chemicals Rate is low Transposons “jumping genes” Can move to new locations and disrupt sequences

Point Mutations Point Mutations Change in a single nitrogen base Examples: Insertion Deletion Substitution

Frameshift mutations Frameshift mutation is when an entire sequence of amino acids is interrupted/changed Caused by insertions Transposons deletions

Mutations Missense mutations Change in only a few amino acids  protein can function, but causes problems (sickle cell anemia) EX: THE CAT ATE THE HAT THE MAT ATE THE HAT

Mutation Silent mutations No change in Amino Acid (redundancy)

Frameshift Mutation Change “coding frame” (how the codon is read)

Frameshift mutation Nonsense mutations Changes whole amino acid sequence  protein can’t function Changes the amino acid codon to a stop Ex: THE CAT ATE THE HAT THE CAT

Transposons Discovered by Barbara McClintock “Jumping Genes”  genes that can “move” within or between chromosomes May increase or decrease gene expression May destroy gene expression

Learning Check! What can cause a mutation? What type of mutation does not lead to a different amino acid/protein? What type of mutation causes the protein to stop early? What type of mutation changes one or two amino acids, but the protein still functions more or less?