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Competent Host For Transformation with rDNA MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #NEET

Quick Facts

  • Competent Host (For Transformation with Recombinant DNA) is considered one of the most asked concept.

  • 4 Questions around this concept.

Concepts Covered - 0

Competent Host (For Transformation with Recombinant DNA)
  • For propagation of DNA molecules host cells are required. 
  • Host cells like E. coli, yeast and plant and animal cells are being used.
  • Since DNA is a hydrophilic molecule, it cannot pass through cell membranes.
  • In order to force bacteria to take up the plasmid, the bacterial cells must first be made ‘competent’ to take up DNA.
  • This is done by treating them with a specific concentration of a divalent cation, such as calcium, which increases the efficiency with which DNA enters the bacterium through pores in its cell wall.
  • Positively charged calcium ions(Ca2+) attract both the negatively charged DNA backbone (phosphate) and the negatively charged groups in the lipopolysaccharides inner core.
  • Recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them briefly at 420C (heat shock) and then putting them back on ice. 
  • This enables the bacteria to take up the recombinant DNA.
  • Incubation on ice will reduce the thermal motion of molecules and so further promote the binding process. 
  • Upon heat shock, the cell membrane alters in a way that allows DNA uptake without losing the internal contents.
     

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