3) Caucasian humans have a gene which determines the curliness of hair. Individuals with straight hair are homozygous for the straight allele while those with curly hair are homozygous for the curly allele. Heterozygotes have wavy hair.
a) If two wavy haired people mate, what phenotypes and genotypes would you expect among their offspring?
b) If ALL of the many children of another couple have wavy hair, what would the most likely genotypes of the parents be?
a. Do a Punnett square, with each parent is cs as a genotype.
http://anthro.palomar.edu/mendel/mendel_2.htm
b. Try cc and ss.
a) To determine the possible phenotypes and genotypes of the offspring, we need to consider the genetic inheritance pattern for hair curliness. In this case, individuals with straight hair are homozygous for the straight allele, individuals with curly hair are homozygous for the curly allele, and heterozygotes have wavy hair.
If both parents have wavy hair (heterozygous genotype), there are three possible genotypes for their offspring: straight (homozygous for the straight allele), wavy (heterozygous), and curly (homozygous for the curly allele). The phenotypes would be straight hair, wavy hair, and curly hair in varying proportions depending on the probability of each genotype being passed on.
The expected genotypic ratio among the offspring would be 1:2:1, which means that for every one individual with a straight hair genotype, there would be two individuals with a wavy hair genotype, and one individual with a curly hair genotype.
b) If all of the children of another couple have wavy hair, this implies that both parents must have the same genotype. Since all the children have wavy hair (heterozygous genotype), it suggests that both parents are heterozygous for hair curliness.
The most likely genotypes of the parents would be heterozygous (Ww) for the hair curliness gene. This would result in all their offspring having a wavy hair phenotype.