Waxy endosperm (wx), shrunken endosperm (sh) and yellow seeding (v) are encoded by three recessive genes in corn that are linked to chromosome 5. A corn plant homozygous for all three recessive alleles is crossed with a plant homozygous for all the dominant alleles. The resulting F1 are then crossed with a plant homozygous for the recessive alleles. Their progeny are: wx sh v+ 87 wx+ sh+ v 94 wx+ sh+ v+ 3479 wx sh v 3478 wx+ sh v+ 1515 wx sh+ v 1531 wx sh+ v+ 292 wx+ sh v 280 Total #: 10756 a. Determine the order of the genes on the chromosome. (5 points) b. Determine the recombination frequencies and draw the genetic map. (15 points) c. Determine the amount of interference occurring between these genes. (5 points)
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First, we need to determine the order of the genes on the chromosome. To do this, we will look for the double crossover progeny, which are the least frequent. In this case, they are: wX sh v+ (87) and wx+ sh+ V (94) This tells us that the sh gene is in the Show more…
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In corn, waxy endosperm (wx), shrunken endosperm (sh), and yellow seedlings (v) are encoded by 3 recessive genes located on chromosome 5. A corn plant homozygous for all 3 recessive alleles is crossed with a plant homozygous for all the dominant alleles. The resulting F1 are then crossed with a plant homozygous for the recessive alleles in a 3-point testcross. The progeny of the testcross are: wx sh V 82 Wx Sh v 91 Wx sh V 3,449 wx Sh v 3,458 Wx sh v 1,525 wx Sh V 1,531 wx sh V 292 Wx Sh v 289 Total 10,717 a. Determine the order of the genes on the chromosome. b. Calculate the map distances between the genes. c. Determine the coefficient of coincidence and the interference among these genes.
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Waxy endosperm (a), shrunken endosperm (h), and yellow seedling (e) are encoded by three recessive genes in corn that are linked on chromosome 5. A corn plant homozygous for all three recessive alleles is crossed with a plant homozygous for all the dominant alleles. The resulting F1 are then crossed with a plant homozygous for the recessive genes. The F2 progeny are given below: a h E 87 A H e 94 A H E 3,479 a h e 3,478 A h E 1,515 a H e 1,531 a H E 292 A h e 280 Total 10,756 a) Identify the genes on the chromosome drawn below according to their relative order. b) Calculate the map distance between them (show your calculations). a) Gene 1: Gene 2: Gene 3:
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Waxy endosperm (wx), virescent seedling (v), and shrunken endosperm (sh) are all recessive mutants in corn. Waxy and shrunken are both on chromosome 9, located 18 map units apart. Virescent is on chromosome 5 and is not linked to the other loci. A strain of corn that is homozygous for waxy and virescent is crossed to a strain that is homozygous for shrunken endosperm. The F1 were entirely wild type. An F1 individual was then test crossed to a strain that is homozygous for waxy, virescent and shrunken. Of 1000 offspring, how many of the offspring will be virescent and shrunken, but not waxy? 205 430 230 215 200 How many of the offspring will be waxy, virescent and shrunken? 35 45 75 100 220
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