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(A) You are interested in understanding the genetics of 3 traits in maize-purple

ID: 207510 • Letter: #

Question

(A) You are interested in understanding the genetics of 3 traits in maize-purple leaves and silk color. You cross a pure-bred line of corn that has purple leaves and salmon silk with true-breeding wild type corn. The cross produces 442 seeds that when planted grow into corn plants that have purple leaves and yellow silk. You next cross these plants with a green plant that has salmon silk, which results in the following progeny: · 240 plants with purple leaves & yellow silk 220 plants with green leaves & salmon silk 36 plants with purple leaves & salmon silk 24 plants with green leaves & yellow silk i) Are the genes influencing leaf color and silk color linked? i) If so, what is the map distance between these 2 genes?

Explanation / Answer

1. To calculate if the genes are linked or not we calculate Recombination frequency. if it is 50% or more genes are unlinked

recombination frequency= total number of recombinants/total number of offsprings*100

=(36+24)/442*100

= 13.5%

recombination frequency is less than 50% so genes are linked

2. Since recombination frequency is 13.5% so map distance between two genes is 13.5 centimorgan.