DNA delivery by microinjection — Which statement is NOT true about microinjecting DNA into plant protoplasts?

Difficulty: Easy

Correct Answer: It employs a needle with a diameter greater than the cell diameter

Explanation:

Introduction / Context:Microinjection is a direct physical method for introducing DNA, RNA, or proteins into individual plant cells or protoplasts. The technique requires precision instrumentation and gentle handling to avoid lysis, especially because protoplasts lack a cell wall and are osmotically fragile.

Given Data / Assumptions:

  • Protoplasts are spherical, wall-less cells enclosed only by a plasma membrane.
  • Micromanipulators and microcapillaries are standard equipment.
  • Cells must be stabilized during injection to prevent movement and damage.

Concept / Approach:The microinjection needle must be substantially finer than the target cell to penetrate the membrane with minimal disruption. A needle larger than the cell diameter would catastrophically damage the cell. Therefore, the statement claiming a larger-than-cell needle is used is not true.

Step-by-Step Solution:

Confirm core setup → micromanipulator and microcapillary are correct.Confirm immobilization → true for positional control.Evaluate needle size → must be smaller than the cell; a larger needle is incorrect → choose option (c) as NOT true.

Verification / Alternative check:Protocols specify tip diameters in the submicron to a few microns range, far below typical protoplast diameters (20–50 microns).

Why Other Options Are Wrong:

a,b) Both accurately describe the procedure.d) Cannot be true because (c) is false.e) Reaffirms correct practice (fine needle smaller than cell diameter).

Common Pitfalls:Using excessive injection pressure or a too-wide tip causes lysis; osmotic stabilization and gentle manipulation are essential.

Final Answer:It employs a needle with a diameter greater than the cell diameter.

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