Gene Combo 2-5-15 Key Question: How do genes determine a trait?
What happens to the parents gene that doesnt show? Initial
thoughts:
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Evidence: Poppy & Skye Generation 1: Skye (blue tail) Poppy
(orange tail) TTtt Homozygous = 2 copies of the same gene Blue, or
T, is dominant over Orange, or little t. Little t is recessive.
What is Skyes phenotype? What is Skyes genotype?
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Generation 2 (Skye & Poppys Offspring) OceanLucyTt
Heterozygous = 2 different genes What is their genotype? What is
the phenotype?
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Evidence 2: Coin Toss Model Paste the chart into your notebook
Use the coin to represent whether Ocean & Lucys offspring get T
or t. Heads = T Tails = t Remember: TT = blue tT or Tt = blue tt =
orange
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Graph your results
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Analysis Questions 1.What is the ratio of blue-tailed to
orange-tailed critter pups? a)Ration = Number of blue tailed
offspring Number of orange-tailed offspring b)Round this to the
nearest whole number. Then express as a ration by writing it like
this: _______ : 1 c)Express this ration as a pair of fractions, so
that you can use them to complete the following sentence: About
_____ of the offspring have blue tails, and about _____ of the
offspring have orange tails. d)Why isnt the ration 1:1 or half blue
half orange?
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Analysis Questions contd 2.You and your partner are about to
toss 2 coins 100 times. Predict how many times the outcome would
be: a)Heads-heads b)Heads-tails c)Tails-heads d)Tails-tails 3.Look
back at the Creature Features lesson. Do the results of the coin
tossing model match the Generation Three critter data?
Explain.
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Summary What did you think about how genes determine a trait
before? What did you learn from your evidence about how genes
determine a trait? What are some further thoughts or questions you
have about how genes determine a trait?
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Reflection Write a letter to the Zoo explaining your findings
about tail color traits and their chances.
