Problem1

You are doing a genetics experimentwith the fruit fly. In the “P” generation, you cross twotrue-breeding flies. Thefemale parent is brown and wingless and themale parent is black with normal wings. All of the flies in theF1generation are brown and have normal wings.

Assume the genes are not found on asex chromosome. Indicate the body color alleles withB and b andthewing size alleles with N andn.

a) The genotypes ofthe flies in the P generation are: Female:_____BBnn_________Male:___bbNN___

b) The genotype of the flies in theF1 generation is: __BbNn___________

c) You now take anF1 female and cross her to a true-breeding black, wingless male.This male’s genotype is:_____bbnn_________

d) When the flies in(b) and (c) are mated, you count 1600 offspring in the F2generation. If the body color geneand wing type genes are notlinked, how many flies of each phenotype would you expect? (Be sureto use a Punnett square for a dihybrid cross to show yourwork.)

Show yourwork:  

Expected flies:

   _0_: # of brown, winged flies (Genotype:__BbNn__)

__800__: # ofblack, winged flies (Genotype: ___Bbnn___) __800___: # of black,wingless flies (Genotype: ____bbNn___) __0_____: # of brown,wingless flies(Genotype: __bbNN___)

e) When you countthe F2 generation, you actually get 85 brown, winged flies, 728black, winged flies, 712 brown,wingless flies, and 75 black,wingless flies. These results indicate that the body color and wingsize are linkedgenes.

·What are thephenotypes of the recombinant flies? (Hint: Refer back to the Pgeneration flies in the first paragraph. Recombinant flies do notresemble the original P generation phenotypes.)

·Calculate therecombination frequency (%) between the linked genes for body colorand wing size.

Problem2

You cross a true-breedingyellow-bodied, smooth-winged female fly with a true-breedingred-bodied, crinkle-winged male. The red body phenotype is dominantto the yellow body phenotype and smooth wings are dominant tocrinkled wings. Use B orb for body color alleles, andW or w for wingsurface alleles.

a) What are the genotypes of the Pgeneration flies?

b) What will be the genotype(s) andphenotype(s) of the F1 offspring?

c) You discover thatthe genes for body color and wing surface are linked. You perform adihybrid test crossbetween the F1 flies from part (b) with atrue-breeding yellow-bodied, crinkle-winged fly. Use thefollowingF2 results to determine the recombination frequency (%)between the body color and wing surface genes. (Remember that therecombinants are the ones that do not resemble the parental typesfrom the P generation.)

Body Color	Wing Surface	# of Individuals
red	smooth	102
yellow	smooth	404
red	crinkled	396
yellow	crinkled	98

You decide to turn your attention toa different gene, one that controls wing length. This gene has twoalleles, \"L orl\" where long wings are dominant to short wings.Remember that the red body phenotype is dominant to the yellow bodyphenotype. You again mate two true-breeding flies:

P: red-bodied,short wing male X yellow-bodied, long wing female

F1: All red-bodied,long wing

d) You perform atest cross between the F1 flies above with true-breedingyellow-bodied, short-winged flies. You get the following F2results. What is the recombination frequency (%) between the genesfor body color and winglength?

Body Color	Wing Length	# of Individuals
red	long	45
red	short	460
yellow	long	440
yellow	short	55

e) Based on the information in (c) and (d), what are the twopossible arrangements of these three genes: body color,wing surfaceand wing length? Draw two linkage maps to show the possiblearrangements of these genes and the map distance between genes