Explain how to do this with your answer please: Answer Choices: lys, gln, or phe

Question

Explain how to do this with your answer please:

Answer Choices:

lys, gln, or phe

phe and lys, gln and lys, or gln and phe

DNA containing the genes gln+ phe+ lys+ was used to transform bacterial cells of genotype gln- phe- lys-. The following cell types were obtained with the number of each cell type shown below: Genotype Number gln+phe+lys+ 25 gln+phe+lys2 gln+phe-lys-8 gln+phe-lys+ 4 gln-phe+lys14 Genotype gln- phe-lys1 gln- phe-lys-19 Which gene is in the center? Which two genes are the closest together?

Explanation / Answer

Based on the given data, the genotype obtained with highest number is considered as parental genotype. They are number 25 and 19. Thus, the total number of parental phenotypes is 44. The genotypes single crossovers are, 8, 4, 14, and 7. The genotypes double crossovers are 2 and 1. Thus, the total number of recombinant phenotypes is 36. The total progeny is 80.

RF = recombinant progeny / total progeny %

The recombination frequency of parental genotypes is: 44/80 = 0.55 m.u

The recombination frequency of single crossovers is: 33/80 = 0.41 m.u

The recombination frequency of double crossovers is: 3/80 = 0.03 m.u

Here, the parental genotypes are: Gln+Phe+Lys+ and Gln-Phe-Lys-

The genotypes of double crossovers are: Gln+Phe+Lys- and Gln-Phe-Lys+

Gene Lys has switched sides between the parental and the double crossovers, so Lys is in the middle. Thus, the first answer is Lys.

The closest genes together are Gln and Lys.

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