Answer to Question #301464 in Genetics for isaiah

Question

A widow's peak hairline is dominant (W) to a straight hairline (w). Karen and her brother both have a straight hairline, but her parents and sister all have a widow's peak. Complete the Punnett square that shows Karen's family.

Answer 1

Karen and her brother both have a genotype 'ww' (phenotype straight hairline), whereas the father and sister have a genotype 'Ww' (phenotype peak hairline).

• A Punnett square is a representation of how different gametes combine to produce distinct genotypes from a given genetic cross.
• A Punnett square is very useful to decipher the possible expected genotypes and phenotypes of a given genetic cross.
• In this case, the father will be heterozygous 'Ww', thereby producing two types of gametes: W and w, whereas the mother will be homo-zygous 'ww', producing only one type of gamete: w.

In conclusion, Karen and her brother both have a genotype 'ww' (phenotype straight hairline), whereas the father and sister have a genotype 'Ww' (phenotype peak hairline).