Question

PEDIGREES When a trait follows Mendelian inheritance it is often possible to figure out its dominance state by using a pedigree. Below are four pedigrees for four different traits. They are all autosomal traits (meaning they are not inherited on the X or Y chromosomes). For each trait, determine if it is dominant, recessive or unable to be determined. And explain each answer If it helps your explanation, you may label the symbols with letters Remember squares are males, circles are females. Filled symbols are individuals that express the trait; open symbols are those that do not. Refer to p. 276 of your text to help you understand the pedigrees 19. Is this pedigree dominant/recessive/unknown? Explain your reasoning. 20. Is this pedigree dominant/recessive/unknown? Explain your reasoning 21. Is this pedigree dominant/recessive/unknown? Explain your reasoning 22. Is this pedigree dominant/recessive/unknown? Explain your reasoning.

Answer 1

19) Autosomal dominant because if it was recessive all the progenies will be affected. Genotype can be for this is both parents have Aa and the resulting progenies both have aa.

20) Autosomal recessive.

The genotype of parents are Aa so they are unaffected but the progenies get aa genotype and they are affected and some have Aa or AA and that is why they are unaffected.

21)

unable to be determined because it can be recessive or dominant both because if both parents have aa then all progenies will recieve aa and all will be affected im caee of autosomal recessive and if parents have AA then too all progenies will have AA in case of Autosomal dominant.

22) Autosomal recessive because in Autosomal dominant unaffected parents can not have affected progenies.