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Kaplan Qbank USMLE



Author5 Posts
  #1

How is a prophage created?
A. Through activation of the recA gene produce of an exogenote

B. Through infection of a bacterial cell with a virulent bacteriophage

C. Through site-specific recombination of a temperate phage and bacterial DNA

D. Through infection of a bacterial cell with lambda phage, lacking the lambda receptor

E. Through excision of bacterial DNA and active lytic replication of a bacteriophage

Please explain.

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  #2

C ?

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  #3

Yes. Its C.

Site-specific recombination of phage DNA into bacterial cell DNA by the process of lysogeny creates a prophage. The RecAgene product is necessary for homologous recombination with an exogenote but does not create a prophage. A virulent bacteriophage causes lysis of the host cell and not the production of the prophage. The lambda repressor is necessary in such cases to prevent the lytic life cycle.
Choice E may be the pathway a prophage may choose to reinitiate its bacteriophage lytic lifestyle, but it would not be a means to create a prophage.

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Our greatest glory is not in never falling, but in rising every time we fall.

  #4

hey drvirgo, i am a second mbbs student and I just happened to visit the site, i love your posts, i mean they drive basic misconceptions away....keep it up.....thankssmiling face

  #5

Thanks sugandhna. I hope you will post some interesting q's or anything else interesting on here as well. smiling face

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