DNA Uptake and Bacterial Competence — NEET Biology
📚 Practice ConceptSince DNA is a hydrophilic molecule, it cannot pass through cell membranes. Why? 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
Which of the following statements about methods for introducing alien DNA into host cells are NOT correct? S1: Micro-injection is a technique where recombinant DNA is directly injected into the cytoplasm of plant cells. S2: Biolistics or gene gun method is suitable for plants, involving bombardment with micro-particles coated with DNA. S3: Transformation of bacterial cells typically involves making them competent using divalent cations like calcium and applying heat shock. S4: Disarmed pathogen vectors, such as modified retroviruses, are used to deliver desirable genes into animal cells. S5: Since DNA is a hydrophilic molecule, it readily passes through the cell membranes of most host cells without any special treatment.
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