Question

In an experiment you grow some cells in a media containing heavy isotopes of C and N. Then you transfer then to a lighter media. If you centrifuge the ribosomes so obtained after an hour how many bands will you expect?

(a) 1

(b) 2

(c) 3

(d) 4

The question was asked in an internship interview.

Enquiry is from Ribosome as Ribozyme in portion Gene Expression : Translation of Cytogenetics

Answer 1

The correct choice is (d) 4

To explain I would say: You will obtain 4 bands corresponding to heavy 50 and 30S subunit, heavy 50S and light 30S subunit, heavy 30S and light 50S subunit and light 50S and 30S subunit respectively.