Question

Consider the pedigree for a single mendelian gene W in a family, some of whose members exhibit the dominant trait, wooly hair, indicated by filled symbols. What is the probability that individual III-1 (indicated by "1" in the third generation) is Ww?

Answer 1

Without specific information from the pedigree, it is not possible to accurately determine the probability that individual III-1 is heterozygous (Ww) for the wooly hair trait. General Mendelian genetics principles suggest that if both parents are heterozygous, the probability would be 50%.

Step-by-step explanation:

The question is asking for the probability that individual III-1, a member of the third generation in a Mendelian pedigree, is heterozygous (Ww) for a gene W that exhibits a dominant trait. To calculate this probability, one needs to analyze the pedigree and apply knowledge of Mendelian genetics.

In a scenario where the dominant phenotype is expressed in the pedigree, an individual might be either homozygous dominant (WW) or heterozygous (Ww). However, without specific information from the pedigree provided in the question, a calculation of III-1's genotype cannot be accurately made. If the parents' genotypes are known and they both have the dominant phenotype, the chance of III-1 being heterozygous (Ww) would be 50% if one parent is heterozygous (Ww), assuming the other parent could either be homozygous dominant (WW) or heterozygous (Ww) as well.

However, general Mendelian genetics principles indicate that if two parents are heterozygous (Ww), their children have a 1 in 4 chance of being homozygous recessive (ww), a 2 in 4 chance of being heterozygous (Ww), and a 1 in 4 chance of being homozygous dominant (WW). Considering these ratios, if it is known that both parents are heterozygous, the probability that III-1 is heterozygous (Ww) would be 50%, or 2 in 4.