Tay–Sachs disease is an autosomal recessive disorder. Homozygous recessive individuals lack a key enzyme called hexosaminidase A
, which presents as progressive mental and motor deterioration until death occurs around age 5. Heterozygous individuals, called Tay–Sachs carriers, develop no symptoms of the disease. Tay–Sachs disease was historically more prevalent within populations of Ashkenazi Jews, Pennsylvania Dutch, southern Louisiana Cajuns, and eastern Quebec French Canadians. Today, individuals descended from these populations are more likely to be Tay–Sachs carriers, but genetic testing within these populations has largely eliminated the occurrence of Tay–Sachs disease. For a randomly mating population, calculate the Tay–Sachs carrier frequency to three decimal points if 1 in 3600 individuals develops Tay–Sachs disease.
5 chromosomes. Meiosis results in 4 haploid cells, meaning they have "n" pairs of chromosomes. The diploid cell that the 10 chromosomes originated in has "2n" pairs. This leaves us with a simple equation to solve the problem, 2n=10, so n must equal 5 chromosomes.
