Chromosome Mutations in Meiosis April 23 2019 Mutations

Chromosome Mutations in Meiosis April 23, 2019

Mutations

Mutations � Sometimes pieces of chromosomes are lost, duplicated or moved within a chromosome or to another chromosome during meiosis

Mutations � Sometimes pieces of chromosomes are lost, duplicated or moved within a chromosome or to another chromosome during meiosis � These changes are called mutations

Mutations � Sometimes pieces of chromosomes are lost, duplicated or moved within a chromosome or to another chromosome during meiosis � These changes are called mutations � These mutations affect many genes in the chromosome and change the proteins made by those genes

Some types of chromosome Mutations mutations

Mutations

Mutations � Mutations also occur when cells are exposed to mutagens such as radiation or chemicals

Mutations � Mutations also occur when cells are exposed to mutagens such as radiation or chemicals � E. g. some fruit flies exposed to mutagens have legs growing where antennae should be

Whole Chromosome Mutations

Whole Chromosome Mutations � Whole chromosome mutations can occur in meiosis I (when homologous chromosomes fail to separate) or in meiosis II (when sister chromatids fail to separate)

Whole Chromosome Mutations � Whole chromosome mutations can occur in meiosis I (when homologous chromosomes fail to separate) or in meiosis II (when sister chromatids fail to separate) � The result is that one gamete has 2 copies of the same chromosome and the other will have no copy of that chromosome

Whole Chromosome Mutations

Whole Chromosome Mutations

Whole Chromosome Mutations � Usually whole chromosome errors are prevented from being passed along because the offspring either fails to develop or does not live to reach reproductive age and adulthood

Whole Chromosome Mutations � Usually whole chromosome errors are prevented from being passed along because the offspring either fails to develop or does not live to reach reproductive age and adulthood � Some chromosome mutations result in genetic disorders or syndromes such as Down syndrome

Karyotype

Karyotype �A picture of an individual’s chromosomes, arranged by size

Karyotype �A picture of an individual’s chromosomes, arranged by size

Karyotype

Karyotype � Karyotypes can show genetic disorders

Karyotype � Karyotypes can show genetic disorders � The karyotype of a person with Down syndrome:

Karyotype � Karyotypes can show genetic disorders � The karyotype of a person with Down syndrome: A person with Down syndrome has an extra 21 st chromosome

Karyotype � Karyotypes can show genetic disorders � The karyotype of a person with Down syndrome: A person with Down syndrome has an extra 21 st chromosome This individual is a male because they have a Y chromosome

Karyotype � Karyotypes can show genetic disorders � The karyotype of a person with Down syndrome: A person with Down syndrome has an extra 21 st chromosome This individual is a male because they have a Y chromosome (Females have 2 X chromosomes)

Edwards Syndrome

Turner Syndrome

Textbook Questions � Page 203 #1 -18