PROBLEM
How do you read a pedigree chart?
BACKGROUND INFORMATION
A Pedigree chart is a device used to trace genetic traits through a number of generations. It can be used to study the inheritance of certain diseases or disorders in humans, such as albinism. It shows the possible combination that can result when two organisms are crossed.
MATERIALS
Pencil and paper
PROCEDURE
The following symbols will be used in the pedigree chart.
(figure available in print form)
1. Study the pedigree charts shown for two parents who have albinism.
(figure available in print form)
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Explain the results:
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(The mating of parents who have albinism almost always result in all offspring having albinism)
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2. Develop a pedigree charts showing albinism among the offspring of a father with albinism and a mother who does not carry the trait.
(figure available in print form)
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3. Study the chart in which parents with albinism produced offspring that do not have albinism.
(figure available in print form)
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How can this be so?
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(The parents have albinism for different reasons)
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Can your predict if the grandchildren or great-grand children will have albinism?
EXAMPLES OF PEDIGREES
The individuals represented by the solid square and solid circles show a certain trait.
Example 1:
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Example 2:
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