Question

The process of nuclear envelope breakdown during prophase is NOT aided by which one of the following?

• A. Extension of the filopodia
• B. Phosphorylation of nuclear membrane proteins
• C. Cytoplasmic microtubule dynamics
• D. Nuclear lamina disassembly

Hint:

During prophase, nuclear envelope breakdown is regulated by phosphorylation, microtubule dynamics, and the disassembly of the nuclear lamina, but not by the extension of filopodia.

Answer 1

The Correct Option is A

Step 1: Understanding the process of nuclear envelope breakdown.
Nuclear envelope breakdown is an essential event during mitosis. In prophase, the nuclear envelope starts to disassemble to facilitate the separation of genetic material. This process is regulated by mechanisms such as protein phosphorylation, microtubule dynamics, and the disassembly of the nuclear lamina.

Step 2: Analyzing the options.

• Option 1: Extension of the filopodia: ❌ Filopodia are actin-based structures involved in cell movement and sensory functions, not in nuclear envelope breakdown. Therefore, extension of the filopodia does not contribute to the breakdown of the nuclear envelope during prophase.
• Option 2: Phosphorylation of nuclear membrane proteins: ✅ Phosphorylation of nuclear membrane proteins is a critical step in nuclear envelope disassembly. Phosphorylation of lamins and other proteins contributes to breaking down the nuclear envelope.
• Option 3: Cytoplasmic microtubule dynamics: ✅ Microtubules exert forces that help separate the nuclear envelope components, facilitating its breakdown during mitosis.
• Option 4: Nuclear lamina disassembly: ✅ The disassembly of the nuclear lamina, composed of intermediate filaments, is essential for the nuclear envelope breakdown. It allows the nuclear components to be reorganized during mitosis.

Step 3: Conclusion.
The extension of filopodia (Option 1) does not contribute to nuclear envelope breakdown during prophase. Therefore, Option 1 is the correct answer.