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Sex linked traits & pedigree charts

April 7, 2011. Sex linked traits & pedigree charts. Monday: Incomplete & Co-dominance Tuesday: Quest Wednesday: multiple alleles & polygenic inheritance Thursday: sex-linked traits & pedigree charts Friday: PD Day. This week.

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Sex linked traits & pedigree charts

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  1. April 7, 2011 Sex linked traits & pedigree charts

  2. Monday: Incomplete & Co-dominance Tuesday: Quest Wednesday: multiple alleles & polygenic inheritance Thursday: sex-linked traits & pedigree charts Friday: PD Day. This week..

  3. Incomplete Dominance: A condition in which neither allele for a gene completely conceals the presence of the other Co-dominance: The condition in which both alleles for a trait are equally expressed in a heterozygote: both alleles are dominant Multiple alleles: Many traits in humans result from the interaction of more than two alleles for one gene Polygenic inheritance: A trait that is controlled by more than one gene review

  4. Chromosomal Theory of inheritance: • Chromosomes carry genes, the units of heredity • Pair chromosomes segregate during meiosis (each egg or sperm cell has ½ the number of chromosomes as found in the somatic/body cells) Review

  5. Thomas Hunt Morgan (1866-1945): studied fruit flies • Reproduce rapidly • Have a large number of offspring • Males can be easily distinguished from Females Discovered that white-eye mutations only appeared in males Sex-linked inheritance

  6. A trait controlled by genes on the X or Y chromosome • These traits show different rates of appearance between males and females For fruit flies, the eye colour trait is not carried on the Y chromosome, only the X Sex-linked inheritance

  7. Colour blindness: • X-linked recessive, occurs more in males • Hemophilia: • A condition that affects the body’s ability to produce proteins involved in blood clotting Sex-linked inheritance

  8. Recessive lethal: a trait that, when both recessive alleles are present, results in death or severe malformation of the offspring. • Occurs more frequently in males Sex-linked inheritance

  9. Barr Body: (Dr. Murray Barr, UWO) • one of the X chromosomes in females randomly becomes inactive in each cell • Which X chromosome is inactivated is random, some cells may have different X chromosomes & genes expressed. Sex-linked inheritance

  10. Anhidrotic ectodermal dysplasia: patches of skin contain sweat glands and some patches don’t, depending on which X chromosome is active in the cell • Cannot control body temperature properly. Sex-Linked Inheritance

  11. A graphic presentation of a family tree that permits patters of inheritance to be followed for a single gene Pedigree Charts

  12. Read pg 141-142, 163-167 • Genetics worksheet 4 & pedigree examples • Create your own pedigree chart representing a trait in your family. • must have at least 3 generations • Include “key” Homework

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