3. Females among te Another method of obtaining virgin females is to isolate pup

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3. Females among te Another method of obtaining virgin females is to isolate pupae from which t to emerge. Single pupa cases should be placed in small vials containing a narrow strip of moistened paper towel. The vial vial will be a virgin. This method of obtaining virgin females is laborious and can prove unwieldy cause it requires many vials. he adült should be stoppered with cotton. Of necessity, any female hatching alone in a C. Making Crosses when making a cross between two varieties, consider only those characters in which the parent flies differ. For example, in crossing flies having ebony body color with those having white eyes, only body color and eye color need to be observed carefully Secure anesthetized male flies of one variety and anesthetized virgin females of the other. While hold ing the culture bottle on its side, place these flies in the bottle. Be sure to add some dry yeast granules or jeast suspension to the meditum before introducing the flies. Keep the bottle on its side until the flies have m anesthetization. This position will prevent their becoming stuck in the medium. Label the After 7 or 8 days, remove the parent flies (P)) to prevent their being of the first filial generation (Fi) will soon begin to emerge. recovered fro bottle and record data in Table 1.2. confused with or mated with their offspring, Flies After several F, flikes have appeared, anesthetize and examine them, especially with regard to the characters by which the Pi flies differed. Record in Table 1.2 the phenotypes of the Fi flies of each sex; place these F flies in a fresh bottle of medium. (Be sure to label the bottle) This mating will allow for the production of a second filial generation (F2). It is not necessary that the F, female flies be virgins for this mating. I. Why? The instructor may wish to have you testcross an F female fly. In this case you should use a virgin female.

Explanation / Answer

1. Normally, isolation of F1 generation is done during the begining stage of the life and mainatined in closed container. These might have mated with the males in the closed environment, thus virginity is not taken into consideration.

2. In case of testcross, there should be guarantee that females should not have undergone mating before. Thus, it is better to use virgin females in this case.

3. Testcross is defined as crossing of an individual (genotype unknown) with a tester (a homozygous recessive individual), to find the genotype of the former.

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