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Punnett Squares

Punnett Squares. Mr. Mah Ms. Redelmeier Living Environment. HOMOZYGOUS organism with two identical alleles for the same trait (TT or tt). HETEROZYGOUS organism with two different alleles for the same trait (Tt).

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Punnett Squares

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  1. Punnett Squares Mr. Mah Ms. Redelmeier Living Environment

  2. HOMOZYGOUS organism with two identical alleles for the same trait(TT or tt)

  3. HETEROZYGOUSorganism with two different alleles for the same trait(Tt)

  4. DOMINANTallele that is expressed when in the presence of a recessive allele(TT or Tt = tall)

  5. RECESSIVEallele that is expressed only when homozygous(tt = short)

  6. PHENOTYPEphysical characteristics(Tall, Brown)

  7. GENOTYPEthe genetic makeup(TT, TtHh)

  8. My name is Jay-Z… Brown hair is homozygous and dominant. For hair: What is my genotype? What is my phenotype? BB or Bb Brown

  9. My name is Taylor Swift… Brown eyes are homozygous and dominant. For eyes: What is my genotype? What is my phenotype? bb Blue

  10. GENE = Height ALLELE = Tall, Short Gene is represented by the letter “t” Dominant = T Recessive = t Remember: you need 2 copies of every gene!!!

  11. Essential Question:How can we determine what the offspring are going to be?

  12. Answer:PUNNETT SQUARES!

  13. Reginald C. Punnett • Inventor of the Punnett Square

  14. PUNNETT SQUARESchart showing the possible combination of alleles in a cross

  15. Punnett Squares show the probability of getting a certain type of offspring

  16. Think/Pair/SharePunnett Squares can be used to predict the probability of:a) being exposed to a contagious disease and contracting itb) having an inherited disease or a genetically determined physical trait c) both a and b

  17. Think/Pair/SharePunnett Squares can be used to predict the probability of:a) being exposed to a contagious disease and contracting itb) having an inherited disease or a genetically determined physical trait c) both a and b

  18. THE PARENTS GENOTYPES • DAD = Tt (heterozygous) • MOM = Tt (heterozygous) PHENOTYPES • DAD = Tall • MOM = Tall

  19. PUNNETT SQUARES t T T t T T T T t t t t

  20. THE OFFSPRING GENOTYPES 1TT:2Tt:1tt (1:2:1) • TT (homozygous dominant) • Tt (heterozygous) • Tt (heterozygous) • tt (homozygous recessive)

  21. THE OFFSPRING PHENOTYPES 3 Tall :1 Short (3:1) • TT (tall) • Tt (tall) • Tt (tall) • tt (short)

  22. Cross a homozygous dominant with a recessive (for height where T is dominant and tall).Find the genotype and the phenotype

  23. Cross a heterozygote with a recessive (for height where T is dominant and tall).Find the genotype and the phenotype

  24. Cross a heterozygote with another heterozygote (for skin color where Black is B, b = white).Find the genotype and the phenotype

  25. Cross a heterozygote with another heterozygote (for nose size where big nose is N and small nose is n).Find the genotype and the phenotype

  26. A male with black hair, homozygous dominant, has offspring with a blonde woman. What are the ratios of genotypes found in the offspring?

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