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Bacterial strain X is resistant to ampicillin and sensitive to gentamicin. Bacterial strain Y is resistant to gentamicin and sensitive to ampicillin. Bacterial strains X and Y are grown in mixed culture in medium without antibiotics, then the culture is plated on medium containing both ampicillin and gentamicin. Bacterial colonies grow on the plates. In a second experiment, DNase is added to the mixed culture medium. When this mixed culture is plated on medium containing both antibiotics, no colonies grow. Assuming that bacterial cells are impermeable to DNase, which of the following processes best explains these observations?

A. Conjugation
B. Mutation
C. Transduction
D. Transformation
E. Transposition


I dont have the answer for this one .Can someone xplain this...

its....D

can u xplain this...

D???

answe is D...When grown together the bacterias transfer their resistance to each other. But when we add DNase it dosent happen , WHy? cause there is no free DNA to be picked up anymore. Which is transformation. If you are wondering where this free DNA is coming from, well each strain of bacterias is growing but some of them do get destroyed from enviromental or whatever factors

hmmm i think i got it now ... Its cus the first time when theres noDNase bacteria acquire resistance by transformation(picking free DNA from themedium) But the next time DNase kills any free DNA.
Thx turtlerace and leen
GL!!

Thx mehrban...for the wonderful xplanation..GL!!