Figure 10.4
-A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in Figure 10.4. If a female of this species has one chromosome 12 with a blue gene and another chromosome 12 with an orange gene, and has both number 19 chromosomes with short genes, she will produce which of the following egg types?

Question

Quizplus · Accepted Answer

Since the female has one chromosome 12 with a blue gene and one with an orange gene, she is heterozygous for the wing color gene. Since both of her number 19 chromosomes have short antennae genes, she is homozygous for the antennae gene. During meiosis, her chromosomes will segregate independently, meaning that the allele for wing color on one chromosome 12 can be paired with either the allele for wing color or antennae length on the other chromosome 12. Similarly, the allele for antennae length on one chromosome 19 can be paired with either the allele for wing color or antennae length on the other chromosome 19. Therefore, she can produce gametes with the following combination of alleles: blue short, blue long, orange short, or orange long. The only gametes she cannot produce are those with both long antennae and the orange wing color allele, as neither of those genes is present on her chromosomes. Since half of her gametes will carry the blue wing color allele and half will carry the orange wing color allele, and they will all carry the short antennae allele, half of her eggs will be blue/short and half will be orange/short.

Figure 10.4 -A Certain (Hypothetical) Organism Is Diploid, Has Either Blue or Blue