When analyzing a pedigree, how can you determine if an individual is a carrier (heterozygous) for the trait being studied?

Answer 1

If both parents are not showing the trait while one of the children is showing it, then the parents must be heterozygous for it.

When drawing a pedigree, the drawing starts at the top and goes down; however, when reading a pedigree, you should begin at the bottom, where you have the last generation. Before proceeding, review the information provided about the trait (if any) as this will aid in genotype determination. Based on the last generation's phenotype, ascertain the genotype or all possible gnotypes of each individual. Utilizing this information, ascertain the alleles of the upper generation. Proceed in the same manner for the previous generation. In some situations, it is not possible to determine whether an individual is homozygous or heterozygous for a particular trait without a hint.

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Answer 2

Sebastian Alvarado

Look for unaffected parents with affected offspring. If two carriers mate, 25% of their offspring are expected to show the trait.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.