2.5 Pedigree Practice Packet - Oxford Area High School...A pedigree is a visual chart that depicts a...
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Name: _________________________________ Date: _________________ Period: ______ Mod A – Cells & Heredity Lesson 2.5 Page 20 Fry 2017 Pedigree Introduction A pedigree is a visual chart that depicts a family history or the transmission of a specific trait. They can be interesting to view and can be important tools in determining patterns of inheritance of specific traits. Pedigrees are used primarily by genetic counselors when helping couples decide to have children when there is evidence of a genetically inherited disorder in one or both families. They are also used when trying to determine the predisposition of someone to carry a hereditary disease for example, familial breast cancer. The Components of a Pedigree: Squares are used to indicate males in a family. Circles are used to indicate females. If the individual is “affected" by the trait (dominant or recessive) we darken the shape. A line between a male and a female indicates a marriage or union. A line drawn down from the marriage line indicates offspring. Sometimes, you will see some shapes filled in only half way - this notation indicates a hybrid (heterozygous) or carrier of the trait.
Transcript of 2.5 Pedigree Practice Packet - Oxford Area High School...A pedigree is a visual chart that depicts a...
Name: _________________________________ Date: _________________ Period: ______
Mod A – Cells & Heredity Lesson 2.5 Page 20 Fry 2017
Pedigree Introduction
A pedigree is a visual chart that depicts a family history or the transmission of a specific trait. They can be
interesting to view and can be important tools in determining patterns of inheritance of specific traits. Pedigrees
are used primarily by genetic counselors when helping couples decide to have children when there is evidence of
a genetically inherited disorder in one or both families. They are also used when trying to determine the
predisposition of someone to carry a hereditary disease for example, familial breast cancer.
The Components of a Pedigree:
Squares are used to indicate males in a family.
Circles are used to indicate females.
If the individual is “affected" by the trait (dominant or recessive) we darken the shape.
A line between a male and a female indicates a marriage or union.
A line drawn down from the marriage line indicates offspring.
Sometimes, you will see some shapes filled in only half way -
this notation indicates a hybrid (heterozygous) or carrier of the trait.
Name: _________________________________ Date: _________________ Period: ______
Mod A – Cells & Heredity Lesson 2.5 Page 21 Fry 2017
Pedigree Practice
In humans, albinism is a recessive trait. The disorder causes a lack of pigment in the skin and hair making an albino appear very pale with white hair and pale blue eyes. This disorder also occurs in animals, a common albino found in a laboratory is the white rat. The pedigrees below trace the inheritance of the allele that causes albinism.
1. Given the following genotypes, describe the phenotypes (normal or albino).
AA = ________________________________
Aa = ________________________________
aa = ________________________________
Fill out the blanks on the pedigree to the right.
1. How many children does this family have?
_______
2. What are the sexes of the children?
_______
Fill out the blanks of the pedigree to the right (AA,
Aa, aa).
3. How many children does the original
couple have? _______
4. How many grandchildren? _______
Name: _________________________________ Date: _________________ Period: ______
Mod A – Cells & Heredity Lesson 2.5 Page 22 Fry 2017
Fill out the blanks of the pedigree to the right (AA,
Aa, or aa).
5. How many children does the original
couple have? _______
6. How many grandchildren does the
original couple have? _______
7. What is the sex of the grandchild? _______
Rats can produce a lot more offspring than
humans, making a pedigree more difficult to
manage. A researcher has four female white
rats named April, May, June, and July. One
night, the cage was left open in the lab and a
brown rat got into the female's cage. Six
weeks later, the rats had litters of babies of
varying colors. Two of the offspring managed
to reproduce before the researcher was able
to sort out the mess.
The researcher decided to make a
pedigree to determine the genotypes of
the offspring, but he couldn't quite
remember how to make one. The image
below shows his pedigree, can you
determine the rats’ genotypes?
Name: _________________________________ Date: _________________ Period: ______
Mod A – Cells & Heredity Lesson 2.5 Page 23 Fry 2017
8. How many carriers of color blindness are in the pedigree above? _______
9. What gender are all of the carriers? _____________________________
10. Explain why only one gender is able to be a carrier for a sex-linked disorder
such as colorblindness.
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Gray
gray
