Croaking in frogs is controlled by one gene with a pair of alleles - dominant uttering (R) and recessive muttering (r). Eye color is inherited by epistatic interaction of two genes with the following possible phenotypes: A_B_ - blue eyes; A_bb - purple eyes and aaB_ or aabb - green eyes. The frog geneticist mated two purple utteres with the following results: Part A 9/16 purple, utterers 3/16 purple, mutterers 3/16 green. utterers 1/16 green. mutterers What were the genotypes of the parents? a. AabbRr x AaBbRr b. AabbRr x AAbbRr c. AabbRr x AabbRr d. AAbbRr x AaBbRr e. AabbRr x Aabbrr f. AaBbrr x AabbRr

The cross with the correct genotypes of the parents is AabbRr x AabbRr -option C-.

Explanation:

Available data:

Cross)                 AabbRr     x    AabbRr

Gametes)    RAb   Rab   rAb   rab

                    RAb   Rab   rAb   rab

Punnet Square)              RAb            Rab            rAb             rab

                           RAb    RRAAbb    RRAabb     RrAAbb    RrAabb

                           Rab     RRAabb     RRaabb     RrAabb     Rraabb

                           rAb     RrAAbb      RrAabb      rrAAbb     rrAabb

                          rab      RrAabb       Rraabb      rrAabb      rraabb

Note) Each parent has two copies of each gamete, which means that these results should be muliplied by four. But in oder to make it understandable, I resumed it, and just put half of the gametes.

Progeny phenotypes) 9/16 purple, utterers R-A-bb

                                    3/16 purple, mutterers rrA-bb

                                    3/16 green, utterers  R-aabb

                                    1/16 green, mutterers  rraabb

Option a. AabbRr x AaBbRr: Incorrect, as one of the parents has a genotype for blue eyes, A-B-

Option b. AabbRr x AAbbRr: Incorrect, as one of the parents is homozygote for A, so there would not be any green descendant.

Option c. AabbRr x AabbRr: Correct

Option d. AAbbRr x AaBbRr: Incorrect, as one of the parents has a genotype for blue eyes, A-B-

Option e. AabbRr x Aabbrr: Incorrect, as one of the parents is muttering, rr

Option f. AaBbrr x AabbRr: Incorrect, as one of the parents is muttering, rr and has a genotype for blue eyes, A-B-                        

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation: