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Autosomal Pedigrees

Autosomal Pedigrees. Catalyst: Incest increases the likelihood of having a child with birth defects. Why do you think this is true?. Write in complete sentences! Don’t talk during the Catalyst!. Big Q s. Why do some children inherit genetic diseases, but other family members do not?

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Autosomal Pedigrees

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  1. Autosomal Pedigrees • Catalyst: Incest increases the likelihood of having a child with birth defects. • Why do you think this is true? Write in complete sentences! Don’t talk during the Catalyst!

  2. Big Qs • Why do some children inherit genetic diseases, but other family members do not? • What does it means for a disease to “skip” a generation? • What are Huntington’s, Cystic Fibrosis, or Tay Sachs?

  3. Objectives • By the end of today, SWBAT… • Determine if an autosomal disorder is dominant or recessive • Analyze autosomal pedigrees to determine the inheritance of disorders

  4. Agenda • Catalyst • Pedigrees? Pedigreat! • Practice • Exit Question

  5. Autosomal vs. Sex-Linked • Humans have 23 pairs of chromosomes • Autosomes: chromosomes #1-#22 • Sex chromosomes: chromosome #23 (X or Y) • Pedigrees show how traits are inherited across many generations.

  6. Pedigrees • Key Point #1: Symbols show the relationships in a pedigree Male Female Parents Male Female Children

  7. Pedigree Symbols • Unaffected: normal (no disorder) • Affected: has disorder W MAN

  8. What do the symbols mean?

  9. Dominant and Recessive Disorders • Key Point #2: Autosomal disorders are either dominant or recessive • Dominant disorder • Person has disease if there is AT LEAST ONE dominant allele • DD = has disorder • Dd = has disorder • dd = no disorder

  10. Dominant and Recessive Disorders • Key Point #2: Autosomal disorders are either dominant or recessive • Recessive disorder • Person has disease if there are TWO recessive alleles • DD = no disorder • Dd = carrier • dd = has disorder

  11. Dominant Disorders • Key Point #3: There are two tricks to figuring out if a disease is dominant or recessive. • If both parents show the disorder but a child does not, the disorder is dominant. • DD = has disorder • Dd = has disorder • dd = no disorder

  12. Recessive Disorders • If both parents do not show the disorder, but a child does, then it is recessive. • DD = no disorder • Dd = carrier • dd = has disorder

  13. Example 2 – Ms. S does S, s

  14. Example 3 – Help me out! H, h

  15. Huntington’s Disease

  16. How many children did individuals I-1 and I-2 have? • How are III-2 and II-4 related? How are I-2 and III-5 related? • Which members of the family above are afflicted with Huntington’s Disease? • How many girls did II-1 and II-2 have? How many have Huntington’s Disease? • There are no carriers for Huntington’s Disease – you either have it or you don’t. With this in mind, is Huntington’s disease caused by a dominant or recessive trait? Explain how you determined your answer.

  17. Cystic Fibrosis…and some incest 

  18. How are individuals III-1 and III-2 related? • Is the trait for Cystic Fibrosis dominant or recessive? How do you know? • Name 2 individuals that have Cystic Fibrosis. Explainhow you determined your answer. • Name 2 individuals that were carriers of Cystic Fibrosis. Explainhow you determined your answer.

  19. Try the worksheet. Skip numbers 4 – 6. (The paragraph’s information is wrong. It is a pedigree for a recessive trait.) Guided Practice

  20. Exit Question • Draw this pedigree, and label the genotype of each individual. (Use B and b) Write in complete sentences! Don’t talk during the Exit Question!

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