CBSE 2023 · Region 1 · Set 1 · Q19 · 2 marks
(a)Identify and name the structures 'A' and 'B' marked in the image given below :
(A)(B)(ii)State their importance in various biotechnology experiments.Explain the process by which a bacterial cell can be made 'competent' to take up foreign DNA from its surroundings, using divalent cations and temperature treatment.
(a)
Identify and name the structures 'A' and 'B' marked in the image given below :
(A)
(B)
(ii)
State their importance in various biotechnology experiments.
Explain the process by which a bacterial cell can be made 'competent' to take up foreign DNA from its surroundings, using divalent cations and temperature treatment.
Marking-scheme solution
(i) 'A; Circular DNA/Plasmid 'B' Bacteriophage
(ii) (Plasmid)-Can carry foreign gene into the host cell/acts as cloning vector/has selectable marker/ independent of the control of chromosomal DNA/ high copy number (Bacteriophage) -Cloning vector have the ability to replicate in bacterial cells / independent of the control of chromosomal DNA / high copy number per cell. OR
(b) Treating bacteria with specific concentration of calcium (ions)which increases the efficiency with which DNA enters the bacteria through pores in its cell wall, recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them briefly at $\displaystyle 42$°C (heat shock), then putting them back on ice.
Biotechnology : Principles and ProcessesProcesses of Recombinant DNA TechnologyRemembervery_short_answermedium
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CBSE Class 12 Biology past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.