1 / 9

Human Pedigrees

Human Pedigrees . 12.3 pg 255. Pedigrees. Family tree that records and traces the occurance of a trait in a family. Analyze patterns Applies Mendel’s concepts of dominant and recessive alleles. Shapes: Males- squares Females- circles. Pedigree traits .

etheodore
Download Presentation

Human Pedigrees

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Human Pedigrees 12.3 pg 255

  2. Pedigrees • Family tree that records and traces the occurance of a trait in a family. • Analyze patterns • Applies Mendel’s concepts of dominant and recessive alleles. • Shapes: • Males- squares • Females- circles

  3. Pedigree traits • Individuals showing (expressing) the trait are shaded( colored in) • Recessive traits have “ee” genotypes • Pedigrees can be analyzed for recessive, dominant, and sex-linked disorders

  4. Recessive Traits • Most human genetic disorders are in this group. • Range of severity. • Examples- • Albinism- lack of pigment • TaySachs- fatal nerve disease • Cystic fibrosis- defective protein- thick mucous buildup affects breathing, digestion, liver. 1/25 people of European ancestry are affected in the U.S.

  5. Carrier • Has one allele but does not show the symptoms. • Heterozygous for the trait. • Some pedigrees show such individuals as a half shaded circle. • If two carriers have a child there is a ¼ chance the child will have the disorder.

  6. Dominant Traits • Only one allele needed to have disorder (heterozygous Aa or homozygous AA). • Less common • Disorder is in every generation • Examples- • Polydactyl- extra fingers and toes • Achondroplasia- dwarfism • All individuals are heterozygous. • Homozygous is fatal.

  7. Dominant Traits continued • Note- Dominant alleles are not found more often in populations. • Most dominant disorders are fatal before reproductive age. • Exception-Huntington’s disease- nervous disorder- no symptoms until 30s or 40s- so trait passed on to children.

  8. Sex-linked pedigrees • More men have the trait. • Review sex-linked notes

  9. Genetic Counselor • Collects and analyzes family inheritance patterns • Helps interpret genetic test results. • PKU- phenyketonuria- tells if baby is missing and enzyme to process phenylalanine. Diet is critical. • Sweat chloride test- cystic fibrosis. • More than 250 different genetic tests available. • Confidentiality and bioethics an issue

More Related