Please explain as simply as possible how the answer was obtained 3. In the follo

Question

Please explain as simply as possible how the answer was obtained

3. In the following test cross, genes a and b are 15 cM apart: at b /ab x ab /a b Among 1000 progeny observed and counted: I SD progeny are expected to be the result of a crossover. b. How many homozygous recessive individuals were expected? P alo e atb e abt 4. One chromosome in a plant has the genes AB C DEF, and another has the gene s MN O PQR. A reciprocal translocation between these chromosomes produced the following arrangement: A B CPQ R on one chromosome and M N O D EF on the other. a. Draw the pairing arrangement of the translocated chromosomes in prophaseI of meiosis. Be sure to label the chromosomes appropriately and clearly. b. Give the genotype of the euploid gamete that is a translocation heterozygote

Explanation / Answer

Please find the answers below:

Answer 1:

Part 1: According to the information, two heterozygous parents are made to cross having genes a and b which are located only 15cM apart. Thus, these genes will be considered as strongly linked to each other and would not undergo any recombination as their close proximity will prevent their synapse formation, hence crossing over. This suggests that all the 1000 progeny would have the genotype exactly similar to their parents, i.e. all heterozygous. Hence, none of the offsprings would be having a genotype as a result of crossing over.

Part 2: As explained, there would be no event of crossing over between these genes and hence, no homozygous individuals would be observed.

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