Do Now Practice Problems:

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Do Now Practice Problems

• 1. The Jones family is planning to have another
  child. Mrs. Jones is the proud mom of 3 healthy
  boys. In her heart, she has always wanted a
  daughter. What are her chances of her next baby
  being a girl? Show with a Punnett square.
• 2. In cats, black fur is codominant to orange
  fur. Heterozygotes are black orange, called
  calico. Fur color is also sex-linked. In a
  Punnett, cross a black female with an orange
  male. Show the results of the offspring.

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Practice Problem

• The Jones family is planning to have another
  child. Mrs. Jones is the proud mom of 3 healthy
  boys. In her heart, she has always wanted a
  daughter. What are her chances of her next baby
  being a girl? Show with a Punnett square.

X X


X y
X X
X X
50 chance girl
X y
X y
50 chance boy
3

• 2. In cats, black fur is codominant to orange
  fur. Heterozygotes are black orange, called
  calico. Fur color is also sex-linked. In a
  Punnett, cross a black female with an orange
  male. Show the results of the offspring.

Let B black O orange BO calico
XB XB


XO y
XBXO
XBXO
Genotypes 50 XBXO 50 Xby Phenotypes 50
Calico female 50 Black male
XBy
XBy
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Pedigree Charts

• The family tree of genetics

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What is a Pedigree?

• A pedigree is a chart of the genetic history of
  family over several generations.
• Scientists or a genetic counselor would find out
  about your family history and make this chart to
  analyze.

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Constructing a Pedigree

• Female

• Male

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Connecting Pedigree Symbols
Examples of connected symbols

• Parents
• Siblings

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Example

• What does a pedigree chart look like?

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Symbols in a Pedigree Chart

• Affected
• Normal
• Deceased

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Interpreting a Pedigree Chart

• Determine whether the disorder is dominant or
  recessive.
• If the disorder is dominant, one of the parents
  must have the disorder.
• If the disorder is recessive, neither parent has
  to have the disorder because they can be
  heterozygous.

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Example of Pedigree Charts

• Dominant or Recessive?

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Answer

• Dominant

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Example of Pedigree Charts

• Dominant or Recessive?

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Answer

• Recessive

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Summary

• Pedigrees are family trees that explain your
  genetic history.
• Pedigrees are used to find out the probability of
  a child having a disorder in a particular family.
• To begin to interpret a pedigree, determine if
  the disease or condition is dominant or recessive.

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I
1
2
II
3
4
1
2
1
III
2
3
4
IV
1
2
3
1. What is the genotype of IV-1? 2. What is the
genotype IV-3? 3. What is the genotype of
III-1? 4. What is the genotype III-2? 5. What
is the genotype II-3? 6. Is it possible for
individual IV-2 to be a carrier? Why?
Let H hitchhikers thumb h straight thumb
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• Which members of the family above are afflicted
• with sickle cell anemia?
• 8. How are individuals III-4 and III-5 related?
• 9. How are individuals I-1 and I-2 related?
• 10. How are individuals II-7 and III-2 related?
• 11. How are individuals I-2 and III-5 related?
• 12. How many children did individuals I-1 and
  I-2 have?
• How many girls did II-1 and II-2 have?
• How many have sickle cell anemia?
• 14. Label the genotype for
• II-1 _______ II-2 _______ II-6 ________
  II-7 ________
• II-8 _______ III-1_______ III-3 _______

Let D normal d- sickle cell