4.8—Determine the relationship between mutations and human genetic disorders

1. 4.8—Determine the relationship between mutations and human genetic disorders

2. Terms Mutation: a change in a DNA sequence that affects genetic information Monogenic mutation: A change in a single gene Chromosomal mutation: produces changes in whole chromosomes Karyotype: an organized profile of a person’s chromosomes

3. Nondisjunction Homologous chromosomes fail to separate during meiosis. One cell gets 2 copies of a chromosome and the other gets none. Ex: Downs Syndrome (Trisomy 21), Turner Syndrome (one X chromosome), Klinefelter Syndrome (XXY)

5. Translocation A chromosome rearrangement in which part of a chromosome breaks off and reattaches to a different chromosome Usually lethal to fetuses 5% of people with Down’s Syndrome is because of Robertsonian Translocation Often linked to infertility and cancer

7. Inversion A segment of a chromosome breaks off and is reinserted in the same place but reversed No loss of genetic material; may lead to lower fertility rates

9. Deletion Breakage of a chromosome in which the genetic material is lost Large deletions are usually fatal Small deletions are responsible for a wide variety of disorders Ex. Cri du chat syndrome-deletion of part of chromosome 5

11. Point mutation A gene mutation involving the substitution, addition, or deletion of a single nucleotide base. Also called a base pair substitution Examples: Tay-Sachs disease, Huntington disease, hemophillia and some cancers