Answer Happy

Figure 2.21 shows two pedigrees involving two deaf
parents. In one pedigree, none of the children are deaf. In a
second pedigree, all of the children are deaf. It turns out that a
third pedigree pattern not shown in the figure is also possible:
Some of the children of two deaf parents are deaf, and some are
not.
Explain these three pedigree patterns.
Why is it necessary to consider the third possibility when
thinking about the results of a cross as a complementation
test?
(a) Mutations in two different genes (b) Mutations in the same gene 同 1 P AA bb Х aa BB P AA bb X AA bb II ਨੂੰ II 1 Complementation J] Noncomplementation 同 F1 F Aa Bb Genetic mechanism of AA bb complementation Genetic mechanism of noncomplementation Figure 2.21 Locus heterogeneity: Mutations in any one of many genes can cause deafness. (a) Two deaf parents can have hearing offspring if the mother and father are homozygous for recessive mutations in different genes. (b) Two deaf parents with mutations in the same gene may produce all deaf children.