Gene delivery method check: In cell and molecular biology, what is “electroporation” used for when introducing DNA into cells?
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ASeparating charged molecules through a gel using an electric field
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BCombining foreign DNA with an electrically charged vector molecule
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CApplying short high-voltage pulses to transiently permeabilize cell membranes
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DIncreasing the rate of cell division and multiplication
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EFixing cells for microscopy by electrical crosslinking
Answer
Correct Answer: Applying short high-voltage pulses to transiently permeabilize cell membranes
Explanation
Introduction / Context:Electroporation is a widely used physical transfection method for bacteria, yeast, plant, and mammalian cells. By delivering brief, high-voltage electrical pulses, it induces transient pores in the plasma membrane, allowing nucleic acids, proteins, or other molecules to enter the cytoplasm before the membrane reseals.
Given Data / Assumptions:
- Cells are in a conductive buffer with DNA present.
- Electrical pulses are carefully controlled for field strength, duration, and number.
- Membrane integrity is restored after the pulse, permitting recovery and expression.
Concept / Approach:The process relies on electric-field–induced membrane destabilization. The correct description must emphasize transient permeabilization rather than electrophoretic separation or chemical conjugation. Optimizing voltage and capacitance balances high uptake with cell viability.
Step-by-Step Solution:
Suspend competent cells with DNA in an appropriate cuvette.Deliver one or more controlled high-voltage pulses.Immediately add recovery medium and allow cells to recuperate.Select for transformants or transfectants using appropriate markers.Verification / Alternative check:Transformation efficiency increases dramatically compared to no-pulse controls. Colonies carrying the plasmid on selective plates confirm successful DNA entry via electroporation.
Why Other Options Are Wrong:
- Gel separation describes electrophoresis, not electroporation.
- Electrostatic “combining” is not how vector–insert ligation occurs.
- Cell multiplication is a downstream effect of successful selection, not the mechanism.
- Electrical fixation is not a standard microscopy method.
Common Pitfalls:Using high salt buffers causes arcing and cell death; ensure proper cuvette gap and ice-cold handling to improve survival and uptake.
Final Answer:Applying short high-voltage pulses to transiently permeabilize cell membranes