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Tuesday, March 22, 2011

Tuesday, March 22, 2011. Materials: Journal, Pen/Pencil, Textbook Turn In: n/a Warm-Up: Complete the Pedigree Symbols Handout Homework: Finish Pedigree Handout. Due Thursday. Pedigrees. Pedigrees. Found in your book on pages 342-343.

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Tuesday, March 22, 2011

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  1. Tuesday, March 22, 2011 Materials: Journal, Pen/Pencil, Textbook Turn In: n/a Warm-Up: Complete the Pedigree Symbols Handout Homework: Finish Pedigree Handout. Due Thursday

  2. Pedigrees

  3. Pedigrees • Found in your book on pages 342-343. • A pedigree is a chart which shows the relationships within a family. • Pedigrees are used to: • study how the traits are passed from one generation to the next. • inferring genotypes (carriers) • Pedigrees are based on the individual’s phenotype. • So if someone has the trait being studied they are “phenotypically affected.”

  4. Pedigrees • How to read a pedigree… • Square = male or • Circle = female or • Shaded means “PhenotypicallyAffected” or • Un-shaded means “PhenotypicallyUnaffected” or • A line connecting a male and a female represents a marriage. • A line coming off of a male and a female represents their offspring.

  5. Pedigrees • How to read a pedigree… • Sometimes the pedigree will show half filled shapes. This indicates a carrier. • What is a carrier?

  6. Traits continued • Sex-linked trait- gene on allele is located only on the X or Y chromosome. • If sex-linked, the effects are usually seen only in males. • Most sex-linked genes are carried on the X chromosome and recessive • Females: Only express the recessive condition if she inherits two recessive alleles. • Thus chances of inheriting or exhibiting a sex-linked condition are significantly less.

  7. Traits continued • Dominant or Recessive? • Gene is autosomal dominant = every individual with the condition will have a parent with the condition. • Gene is recessive = an individual with the condition can have one, two, or neither parent exhibit the condition.

  8. Traits continued • Heterozygous or homozygous? • Individuals with autosomal traits are homozygous dominant or heterozygous = phenotype will show dominant allele • Individuals that are homozygous recessive = phenotype will show the recessive allele. • Two people who are heterozygous carriers of a recessive mutation will not show the mutation • Can produce children who are homozygous for the recessive allele.

  9. Pedigrees • Practice… • How many children did this first couple have? I. 1 2 II. 3 4 1 2 III. 1 2

  10. Pedigrees • Practice… • How many children did this first couple have? • THREE

  11. Pedigrees • Practice… • How many grandchildren did this first couple have?

  12. Pedigrees • Practice… • How many grandchildren did this first couple have? • TWO

  13. Pedigrees • Practice… • How many people in this family are affected?

  14. Pedigrees • Practice… • How many people in this family are affected? • THREE

  15. Pedigrees • Practice… • How many people can you be certain are carrying the trait?

  16. Pedigrees • Practice… • How many people can you be certain are carrying the trait? • FOUR ?

  17. Pedigrees • Practice… • If the allele for this trait is the letter “e”, assign a genotype to all of the individuals you are sure of.

  18. Pedigrees • Practice… • If the allele for this trait is the letter “e”, assign a genotype to all of the individuals you are sure of. Ee ee ee Ee Ee Ee ee

  19. Pedigrees • Practice… • So which individual is the only one we can not be sure of? Ee or EE

  20. Pedigrees • Practice… • What genotype is individual #14? ?

  21. Pedigrees • Practice… • What genotype is individual #14? Start by labeling what you know for sure. aa aa aa aa aa aa ?

  22. Pedigrees • Practice… • What genotype is individual #14? Move on to the carriers. aa Aa Aa aa Aa Aa Aa Aa aa aa aa aa ?

  23. Pedigrees • Practice… • What genotype is individual #14? Do you know anything else? aa Aa Aa aa Aa Aa Aa Aa aa aa aa aa ?

  24. Pedigrees • Practice… • What genotype is individual #14? Do you know anything else? aa Aa Aa aa A? Aa Aa Aa Aa aa aa aa aa ?

  25. Pedigrees • Practice… • What genotype is individual #14? What must individual #14 be? aa Aa Aa aa A? Aa Aa Aa Aa aa aa aa aa ?

  26. Pedigrees • Practice… • What genotype is individual #14? Do a Punnett Square and the only result is aa. aa Aa Aa aa A? Aa Aa Aa Aa aa aa aa aa You didn’t have to go through it all to get that answer, but it was good practice. aa ?

  27. Pedigrees • Practice… • Label each individual with a number and a genotype (use the letter H).

  28. Pedigrees • Practice… • If individual #10 marries a carrier, what is the probability that their second child will not show the trait? #10

  29. Pedigrees • Practice… • If individual #10 marries a carrier, what is the probability that their second child will not show the trait? h h There is a 50% (or 1 in 2) chance that their second child will not show the trait. Hh Hh H h hh hh

  30. Your turn…

  31. Pedigrees • Assign a number and a genotype to each individual. Use whatever letter you would like.

  32. Pedigrees • If #6 married a carrier, what is the probability their first child will be affected? #6

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