What are the genotypes of these flies

Worksheet

Please make sure you have read through all of the information in the “Questions” and “Information” areas. If you come upon terms that are unfamiliar to you, please refer to your textbook for further explanation or search the word here: http://encarta.msn.com/encnet/features/dictionary/dictionaryhome.aspx

Next, complete the Punnett square activity by clicking on the laboratory notebook. Please be sure to note the possible genotypes of the various flies:

Female, red eyes

Female, red eyes

Female, white eyes

Male, red eyes

Male, white eyes

XRXR

XrXR

XrXr

XRY

XrY

When you have completed the Punnett square activity, return to the laboratory scene to begin the actual laboratory activity.

In this exercise, you will perform a Drosophila mating in order to observe sex-linked trait transmission. Please click on the shelf in the laboratory. Here you will find vials of fruit flies. On the TOP shelf, please click on one of the female vials (on the left side) and then drag it to the empty vial on the shelf below. Please repeat this step using one of the male vials (on the right side). These flies will be used as the parental (P) generation. You may switch your parent choices at any time by dragging out old selections and dragging in new flies. Use the Punnett square below to predict the genotypes/phenotypes of the offspring (Note: refer to the genotype table you created above if needed):

XR

XR

XR

Genotype: XRXR

Phenotype:Red eye, female

Genotype:XRXR

Phenotype: Red eye, female

Y

Genotype:XRY

Phenotype: Red eye, male

Genotype:XRY

Phenotype: Red eye, male

__50_% Female, red eye _0__% Female, white eye _50__% Male, red eye _0__% Male, white eye

When you are finished, click “Mate and Sort”.

You will now see information appear in the vials sitting on the next shelf below. These are the offspring of the parent flies you selected above, and they represent the first filial (F1) generation. In your “Data Table” on the bottom of the page and/or on Table I found at the end of this Worksheet, please input the numbers of each sex and phenotype combination for the F1 generation. These numbers will be placed into the first row marked “P generation Cross”.

You will next need to select one of the F1 female flies and one of the F1 male flies to create the second filial (F2) generation. Drag your selections down to the empty vial on the next shelf below and fill in the Punnett square below to predict the offspring:

XR

XR

XR

Genotype: XRXR

Phenotype:Red eye, female

Genotype:XRXR

Phenotype: Red eye, female

Y

Genotype:XRY

Phenotype: Red eye, male

Genotype:XRY

Phenotype: Red eye, male

__50_% Female, red eye _0__% Female, white eye _50__% Male, red eye _0__% Male, white eye

After clicking “Mate and Sort”, you will now have information on their offspring (the F2 generation) to input into your “Data Table” or Worksheet below. This information will be placed into the second row marked “F1 generation Cross”.

NOTE: there are additional lines remaining to use if your instructor requires the analysis of additional crosses.

Please finish this exercise by opening the “Journal” link at the bottom of the page and answering the questions.

Table I:

Cross Type

Phenotype of Male Parent

Phenotype of Female Parent

Number of Red eye, Male Offspring

Number of White eye, Male Offspring

Number of Red eye, Female Offspring

Number of White eye, Female Offspring

P Generation Cross

Red

Red

50

0

50

0

F1 Generation Cross

Red

Red

50

0

50

0

P Generation Cross

White

Red

47

0

53

0

F1 Generation Cross

Red

Red

22

25

53

0

P Generation Cross

Red

White

0

49

51

0

F1 Generation Cross

White

Red

27

28

20

25

P Generation Cross

White

White

0

51

0

49

F1 Generation Cross

White

White

0

51

0

49

Post-laboratory Questions:

Through fruit fly studies, geneticists have discovered a segment of DNA called the homeobox which appears to control:

Sex development in the flies

Life span in the flies