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PEDIGREE CHARTS

PEDIGREE CHARTS. Identical Twin Studies. Identical twins who are raised apart can have differences that last a lifetime. As you watch the video clip explain how the environment can affect genes. https://www.youtube.com/watch?v=k50yMwEOWGU. What is a Pedigree?.

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PEDIGREE CHARTS

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  1. PEDIGREE CHARTS

  2. Identical Twin Studies Identical twins who are raised apart can have differences that last a lifetime.

  3. As you watch the video clip explain how the environment can affect genes https://www.youtube.com/watch?v=k50yMwEOWGU

  4. What is a Pedigree? A record of the family of an individual

  5. Pedigree Charts A pedigree is a chart for tracing genes in a family.

  6. What do we use it for? • To study the transmission of a hereditary condition

  7. Symbols used in pedigree charts • Normal male • Affected male • Normal female • Affected female • Marriage

  8. Symbols used in pedigree charts How many marriages? • Normal male • Affected male • Normal female • Affected female • Marriage How many children? What gender? Who is affected?

  9. A marriage with five children, two daughters and three sons. The middle son is affected by the condition Eldest child  Youngest child Symbols used in pedigree charts • Normal male • Affected male • Normal female • Affected female • Marriage.

  10. Organizing the pedigree chart How many marriages?

  11. I II III IV Generations are identified by Roman numerals

  12. I II III IV Individuals in each generation are identified by Arabic numerals numbered from the left • Therefore the affected individuals are II3, IV2 and IV3. How many affected boys in generation IV? https://www.youtube.com/watch?v=Wuk0W10EveU

  13. Think critically:Tongue rolling chart Is tongue rolling a dominant or a recessive a trait? Why?

  14. If two affected individuals give rise to an unaffected child the affected condition is dominant • So roller allele is dominant (R) and non-roller allele is recessive (r).

  15. Place the alleles in the offspring (all non-rollers must be genotype rr) rr rr rr rr rr

  16. Continue placing the alleles looking at the offspring of each parent rr rr rr rr rr

  17. rr Rr • If one of the parents is a roller and the other is a non-roller all the roller children must be heterozygous rollers (Rr) • If a roller parent has a non-roller child the parent must be heterozygous. Rr Rr rr Rr Rr rr rr Rr rr

  18. Albinism: what can you infer from this chart?

  19. Place the recessive alleles on the chart

  20. Place the recessive alleles on the chart aa Aa Aa Aa Aa Aa Aa Aa aa aa aa aa

  21. Albinism - a recessive condition • If twounaffectedindividualsgiverise to an affectedchild, the allele for the affected condition isrecessive • The unaffected parents are carriers (heterozygous) • Thusrecessive conditions can skip severalgenerations • Inbreedingincreases the chance of carriers producing an affectedchild.

  22. Polydactyly: what can you infer from this chart?

  23. Polydactyly: what can you infer from this chart? • If two affected parents have an unaffected child the allele for the affected condition is dominant.

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