Final answer:
In a three-point mapping experiment, one can expect non-crossover, single-crossover, and double-crossover offspring, with 64 different genotypes and 16 different phenotypes possible in a trihybrid cross.
Step-by-step explanation:
In a three-point mapping experiment, the three general classes of offspring expected are: non-crossover offspring, single-crossover offspring, and double-crossover offspring. Non-crossover offspring have the original parental combinations of alleles, single-crossover offspring show recombination between two of the three genes, and double-crossover offspring show recombination between all three genes.
As for the number of different genotypic classes expected, a trihybrid cross between parents heterozygous for all three traits behaves in a dominant and recessive pattern, resulting in a variety of genotypic combinations. Considering the independent assortment and potential crossover events, there are 64 different genotypes possible. However, due to the dominance and recessiveness of alleles, these different genotypes can result in a maximum of 16 different phenotypes, following Mendelian genetic principles.