Question

You are attempting to recapitulate the transposon mutagenesis experiment without the benefit of counter selection due to unavailability of a DAP auxotroph Donor. As in the lab, the plasmid requires the Pi protein for replication, and the transposon carries Kanamycin resistance. Your Donor and Recipient strains have the following characteristics ( : presence, -: absence, kan: kanamycin, tet: tetracycline, R: resistant, S: sensitive):
Donor Recipient
pir pir-
kanR kanS
tetS tetR
What would be the appropriate media for carrying out selection and counter selection?
A. Luria Agar
B. Luria Afar + pir
C. Luria Agar + kanamycin + tetracycline
D. Luria Agar + tetracycline
E. Luria Agar + pir + kanamycin
F. Luria Agar + kanamycin

Answer 1

Answer:

C. Luria Agar + kanamycin + tetracycline

Explanation:

Given that the recipient strain is tetracycline resistance and the donor strain is tetracycline sensitive.

Recipient strain is kanamycin sensitive and the donor strain is kanamycin resistance sensitive.

If we grow the recipient cell in Luria agar containing tetracycline then only recipient cells will grow and all the donor cells will die.

If we grow the recipient cell in Luria agar containing kanamycin then only recipient cells that have undergone transposon mutagenesis will grow and along with donor cells.

If the Luria agar has both kanamycin and tetracycline then only the recipient cells that have undergone transposon mutagenesis will grow.

Since recipient cells will acquire pir gene. So it will not require pir in the media.

So correct answer is option C. Luria Agar + kanamycin + tetracycline

Answer 2

Answer:

C. Luria Agar + kanamycin + tetracycline

Explanation:

As you can see in the question above, the recipient strain is resistant to tetracycline and not resistant to kanamycin, while the donor strain is not resistant to tetracycline and is resistant to canycin.

Based on this, we can visualize how the growth of these cells would be in relation to the composition of the culture media. If the culture medium has agar + tetracycline, only resistant strains would grow, in this case, donor strains would die. However, if the culture medium has agar + kanamycin in its composition, the recipient cells can grow, in the same way as donor strains, if a mutation caused by transposons has occurred.

A third situation can happen. There may be a culture medium containing luria agar + kanamycin + tetracycline. In this case, cells that are neither resistant to kanamycin nor tetracycline will be able to grow, however, recipient cells that have been mutated by transposons will be able to grow