MUTATIONS pp. 224-226, 231. MUTATION A change in a genetic trait Either 1) chromosomal or 2) gene mutation Germ cell (gametes) or somatic cell (body)

MUTATIONS

pp. 224-226, 231

MUTATIONA change in a genetic traitEither 1) chromosomal or 2) gene mutationGerm cell (gametes) or somatic cell (body)

Germ cell mutations can be inherited and somatic cell mutations result in cancers

Can be lethal (deadly) even before birth

CHROMOSOMAL MUTATIONS

DELETIONloss of a piece of chromosome

EX. Cri du chat &Wolf-Hirschhorn syndrome

INVERSION AND TRANSLOCATIONInversion: chromosome breaks off and reattaches in reverse

Translocation: piece breaks off and attaches to another

* No problems in an individual since all genes are intact but there are problems with crossing over during meiosis

NONDISJUNCTION

failure of a chromosome to separate from its homologous chromosome

Trisomy - one too many chromosomes (2n=47)

EX: Down Syndrome, Kleinfelter’s Syndrome (XXY)

Monosomy - only one of a homologous pair (2n=45)

EX: Turner Syndrome (X)

KARYOTYPE: photo of chromosomes

GENE MUTATION A change in the genetic code of one gene Only one trait is affected

Point mutation: substitution, addition, or removal of a nucleotide

SUBSTITUTION results in new codon (could be different, same amino acid or stop)

EX. Sickle cell anemia

FRAME SHIFT MUTATION removal or addition of a nucleotide causes shift in entire sequence