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Pedigree Chart. By Shubh, Jung, Ike. What are Pedigrees?.
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Pedigree Chart By Shubh, Jung, Ike
What are Pedigrees? • A pedigree chart shows the phenotypes of a particular organism and its ancestors from one generation to the next. It’s useful in tracing a genetically inherited diseases in one’s family. Despite its limitation, a pedigree can also provide information about the allele of an individual.
Types of Inheritance • Autosomal Dominant: Disease on dominant allele • the condition is transmitted from each generation to the next (AA or Aa means affected) • Autosomal Recessive: Disease on recessive allele - the trait will only show when the individual is homozygous recessive (aameans affected) • X-linked Inheritance: Disease on the X chromosome -the trait is passed down only by the X chromosome. This inheritance could be dominant or recessive • Y-linked inheritance: Disease on the Y chromosome - the trait is passed down only by the Y chromosome
Determining a Pedigree Chart Whether the trait is recessive or Dominant -The trait is dominant when one of the parents in the pedigree have to have the trait.
Determining a Pedigree Chart However in a recessive trait, neither of the parents has to have the disorder because they could be heterozygous.
Determining a Pedigree Chart • Sex linked -Dominant • The trend doesn’t skip a generation • The genotype for the females would be: XX or Xx, Males: X _ • Any male with the trait has to have a mother with the trait.
Determining a Pedigree Chart • Sex linked -Recessive • The trend of the chart could skip generations • The genotype for the females would be: xx, Males: x _ • Most affected individuals would be the males • Females with the trait must have a father with the trait
Pedigree Problem 1. Who in the pedigree has the same Y chromosome as the II-3 male? Give all correct answers. 2. Can the disease be X-linked?
1. Who in the pedigree has the same Y chromosome as the II-3 male? Give all correct answers. I-2, III-2, III-6, IV-2 2. Can the disease be X-linked? No, the disease cannot be X-linked because the II-3 male had the disease. When you are a male, you receive one X chromosome from your mother and one Y chromosome from your father. Therefore, the disease couldn’t have been on the X-chromosome because the II-3 male didn’t receive a X chromosome from his infected father.