Problem 1: - Science with Mr. Louie



Cystic Fibrosis:

Understanding the inheritance and expression of an recessive trait

(Adapted from )

Jean and Phil are each heterozygous for cystic fibrosis Cc. They have various children who marry.  Steve, a husband in the F1 generation is homozygous normal, CC. Nicole, a wife in the F2 generation, has an unknown genotype for the disease.  One of the problems is to figure out what her genotype is.  It is possible to view everyone's chromosomes except Jake and Nicole's.

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1. Jean and Phil have a daughter, Kelly, who has cystic fibrosis.

a. Is it possible that her brother, Jake, has the disease, too?

b. What are the chances that he does have the disease? (25%, 50%, 75%) Explain how you know.

2. If Kelly marries a person who is normal and a non-carrier, will any of her children have the disease? How do you know?

3. Scott, from the F2 generation, marries Nicole and they have two children, one with cystic fibrosis and the other normal. What are Nicole's genes for the cystic fibrosis trait?

4. If Eric were able to take the medical history of his girlfriends, what should he look for in the genetic makeup of a wife to ensure that none of their children would have cystic fibrosis? Can he be sure that none of his grandchildren will have cystic fibrosis?

Problem 1:

Below is a pedigree for an inherited lung disease which is recessive.  Provide the genotypes of each of the individuals marked with lower case letters. Use the letter “A” to represent the genotype.

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Problem 2:

Below is a pedigree for an inherited brain disease which is dominant.  Provide the genotypes of each of the individuals marked with lower case letters. Use the letter “A” to represent the genotype.

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Problem 3:

Below is a pedigree for an inherited heart disease which is recessive.  What is the probability that their child F would have the inherited heart disease?

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Mystery at the Termond Estate

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     Count Ralph and his wife Marie, owners of the Termond Estate, were an elderly couple of some wealth. Ralph died suddenly, when he was struck by lightning in his metal rowboat while fishing in Termond Lake. His body was never recovered. All Count Ralph’s children and grandchildren (who happen to be at the estate at the time for a Father’s Day celebration), eagerly awaited the reading of Count Ralph’s will, since they all knew that they will would provide each blood relative with an equal share of his estate wealth.

     When the lawyer arrived, he noticed that a sum of money had been stolen from Count Ralph’s safe. The sum missing was equal to one person’s portion of the estate value. In addition, a small amount of fresh blood was found on the inside of the safe door, presumably belonging to the thief. As this news was being announced by the lawyer, the maid rushed into the room and revealed that she had walked into Count Ralph’s study and observed the thief quickly slipping out of the patio doors. She had not seen the face or been able to identify the thief, since he or she wore a mask and a bulky overcoat. She did see, however, that the thief had an attached ear lobe.

     Police Detective Morse was called to the Termond Estate. Upon his arrival, he immediately ordered blood typing tests on all in the house, and on the blood smear on the safe (found to be type A-). He also noted the ear lobe type of everyone. After studying the data, Morse called all of the relatives together and announced that he had discovered the identity of the thief. One of the children or grandchildren was not really a blood relative, and the theft of the money was to ensure a share in the inheritance.

Using the data table on the next page, answer the following:

1. Draw this family’s pedigree to help you discover the guilty party. Make sure to write out all the names, the blood types, and earlobes.

2. Who was the thief? Explain how Morse was able to identify the thief.

3. For which individual was the money intended? (i.e., who was not the true blood relative?)

Morse’s Data Table:

|Name |Blood Type |Ear lobes |Parents/ Relationship |

|Count Ralph |? |Free |Married to Marie |

|Marie |AB- |Free |Married to Count Ralph |

|Marcia |O- |Free |Married to Peter |

|Peter |AB- |Attached |Son of Ralph & Marie |

|Margaret |A+ |Free |Daughter of Ralph & Marie |

|David |B+ |Free |Married to Margaret |

|Richard |AB- |Free |Son of Ralph & Marie |

|Olivia |A- |Attached |Married to Richard |

|Stephen |B+ |Free |Son of Ralph & Marie |

|Janette |A- |Free |Daughter of Marcia & Peter |

|Brian |B- |Attached |Son of Marcia & Peter |

|Ted |B- |Free |Son of Marcia & Peter |

|Mark |AB- |Free |Son of Margaret & David |

|Samantha |A- |Attached |Daughter of Margaret & David |

|Mike |AB- |Free |Son of Richard & Olivia |

|Alan |A+ |Attached |Son of Richard & Olivia |

|Lorne |A- |Free |Son of Richard & Olivia |

|Maid |AB+ |Free |N/A |

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