00 Simple Mobile 9:55 PM roosevelt.blackboard.c om 10) Abnormal eye shape in Dro
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00 Simple Mobile 9:55 PM roosevelt.blackboard.c om 10) Abnormal eye shape in Drosophila may be caused by a variety of mutant genes, dominant or recessive, sex- linked or autosomal. One normal-eyed Drosophila melanogaster male from a true-breeding normal stock was crossed to two different abnormal-eyed females with the following results: (2.0 pts) Progeny of female 1 Progeny of female2 FemaleMale Female Male 51 49 102 53 50 the results & furnish genotypes of the male and two females. 11) Assume that you have two recessive traits in dogs fetching and sitting on command: the fetching trait in which g fetches and G does not, and the sitting on command trait in which d sits on command and D does not. You cross a male and female that both fetch and sit and have the genotypes GgDd. (3.0 pts) a. What fraction of the offspring will neither fetch nor sit? b. What fraction of the offspring will be GGdd? "What will be the phenotype of these puppies? c. What fraction of the offspring will not fetch but will sit on command? What are the possible genotypes for these puppies? 12) Julie has two children. One of them is a boy. (3.0 pts.)Explanation / Answer
In progeny female 1, the normal eye gene, is X linked. The female Drosophila has mutant genotype XwXw and the male has normal genotype X, which is dominant. The normal male gives the normal X gene to his daughter females, making the genotype XXw (all normal) but is unable to give the gene to it's sons, who get the chromosome, only from their mothers , and hence their genotype becomes Xw.
In progeny female 2, the gene for eye is autosomal . male genotype is NNw (normal eye, carrier); and the genotype of female is NwNw (abnormal eye).
In F1 cross, half the progeny is NNw (normal) and the rest half is NwNw (abnormal eye). This result is found in both males as well as females. Crossing over is absent in Drosophila males.
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