nadiabarati
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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
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| kingsofke
Forum Guru
Topics: 24
Posts: 715
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DNase which cannot penetrate cell wall is destroying free DNA, without it free DNA got picked up by each strain and both got resistant to both. With DNAse , no free DNA and no transfer of resistance.
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| nadiabarati
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So answer can not be transformation, right? What is the answer then?
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| kingsofke
Forum Guru
Topics: 24
Posts: 715
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I thought my explanation says its transformation. 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.
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In Life there are neither rewards nor punishments, just consequences.
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| doc179
Forum Guru
Topics: 67
Posts: 1,217
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yes kingsofke is right there was free DNA in the culture which got destroyed by the DNAase we added so it is transformation
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