In chr 1 of tomato the two most distant genes are 150 mu apa

In chr. 1 of tomato the two most distant genes are 150 m.u. apart. The total length of chr. 1 is 90,000 kb (kilobases), which amounts in average to 600 kb/m.u. Gene M and R are 0.5 m.u. apart and are located in the peri-centromeric (close to CEN), heterochromatic region of chr. 1. The physical distance in kb between these genes is likely to be: A. between 150 and 300 B. about 300 C. much more than 300 D. 45,000 E. less than 150 The family tree in Fig. 1 illustrates the inheritance of a rare disease condition that manifests itself after age 40. Individuals marked by the ? are too young to be diagnosed. The inheritance is best consistent with the following mode: A. recessive B. dominant C. x-linked recessive D. x-linked dominant E. either recessive or dominant

Solution

The option C is correct. Generally, If genes are 0.5 m.u. apart then they both have distance in Kb is 0.5 x 600Kb = 300Kb. However, in case of pericentromeric position the genes may apart from 5 Kb to 30 Kb distance because the pericentromeric position contains repeats sequence of the same length.