Question

Conjugation and mutagenesis: Select all answers that apply

1). Which media should the donor strain be able to grow on?

A. LB

B. LB+ Kan

C.LB+DAP

D. LB+DAP+Kan

2. Which media should the recipient strain be able to grow on?

A. LB

B. LB+ Kan

C.LB+DAP

D. LB+DAP+Kan

3. Which media should the transformants be able to grow on?

A. LB

B. LB+ Kan

C.LB+DAP

D. LB+DAP+Kan

Answer 1

Firstly i am giving the answer-

1. D. LB+DAP+Kan
2. A. LB
3. B. LB+ Kan

Now comming to the culture media-

• LB or Luria broth is a nutritionally rich medium used for culture and growth of bacteria.
• LB+ Kan is Lauria broth with antibiotic Kanamycin. Kanamycin provides a means of selecting transformants that have taken up donor DNA containing a gene which encodes resistance to kanamycin.
• And DAP stands for-Diaminopimelic Acid. It is an essential components of bacterial cell wall (gram negative bacteria). Without it bacterial cell wall will not be formed.

We can observe bacterial transformation and mutagenesis on the basis of Kan and DAP mediated selection we call this artificial selection .

Firstly Donor strain which contains a certain gene has resistance to antibiotic Kanamycin and these strains can cont grow with out Diaminopimelic Acid. So we can grow this strain in-LB+DAP+Kan media.

Secondly we need recipient strain which will be transformed. This cell dosenot require Diaminopimelic Acid for growth not can grow in presence of antibiotic Kanamycin.

Now conjugation takes place and we have to see is transformation happens or not. Means recipient has been transformed or not. To see this we can use LB+ Kan media. In this media

• donor will not survive as it dosent contains DAP
• non transformed will not survive due to antibiotic Kanamycin.

Consequently, only bacteria that have been successfully transformed will survive.