Three linked autosomal loci were studied in smurfs. Dominant Recessive Locus Hei

Question

Three linked autosomal loci were studied in smurfs. Dominant Recessive Locus Height Color Mood Allele Dwarf Blue Happy Allele Tall Pink Gloomy Pure breeding tall, pink, happy smurfs were mated to pure breeding dwarf, blue, gloomy smurfs. The Fi were testcrossed and the testcross progeny are given below Phenotype tall, pink, happy dwarf, blue, gloomy tall, pink, gloomy dwarf, blue, happy tall, blue, happy dwarf, pink, gloomy tall, blue, gloomy dwarf, pink, happy Total Number 522 497 12 18 79 83 110 107 1428 Determine the order of the loci and the map distances between adjacent loci. Then label the map below. Round your map distances properly to two decimal digits. When labeling the loci on the map, the two outside loci must be in alphabetical order. For example, if you have the following loci: Albinism, Bone length, Cranial size, and Albinism is in the center, you would label the map Bone length - Albinism- Cranial size

Explanation / Answer

tall, pink, happy 522

dwarf, blue, gloomy 497

tall, pink, gloomy 12

dwarf, blue, happy 18

tall, blue, happy 79

dwarf, pink, gloomy 83

tall, blue, gloomy 110

dwarf, pink, happy 107

Total 1428

The highest number of progenies belongs to the parental type and the lowest number of progenies are the progenies which undergone the double crossover event.

So We can conclude that the gloomy and happy alleles are present in the middle

If we want to find out the distance between the gloomy and dwarf then we need

to find out the crossover frequency and divide it by the total number of progeny

Stall, pink, gloomy 12

dwarf, blue, happy 18

tall, blue, gloomy 110

dwarf, pink, happy 107

Linkage distance = total number of recombinant * 100 / total number of progeny

= 247*100/1428

= 17.29

So, map distance between gloomy and dwarf is 17.29 map units or 17.29Cm

If we want to find out the distance between the gloomy and blue then we need

to find out the crossover frequency and divide it by the total number of progeny

Stall, pink, gloomy 12

dwarf, blue, happy 18

tall, blue, happy 79

dwarf, pink, gloomy 83

Linkage distance = total number of recombinant * 100 / total number of progeny

= 192 *100/1428

= 13.44

So, map distance between gloomy and blue is 13.44 map units or 13.44 Cm

So the gene order is Blue Gloomy dwarf

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