Question

During which phase of karyokinesis does the disappearance of the nucleolus and nuclear envelope occur?

• A. Prophase
• B. Metaphase
• C. Anaphase
• D. Telophase

Hint:

The disappearance of the nuclear envelope in prophase marks the beginning of the chromosomal segregation process.

Answer 1

The Correct Option is A

At what stage of nuclear division do the nucleolus and nuclear envelope vanish?

Answer:

The nucleolus and nuclear envelope disappear during prophase of karyokinesis.

Rationale:

Prophase, the initial stage of mitosis or meiosis, is characterized by several significant developments:

• Chromosome formation: Chromatin threads compact, forming observable chromosomes.
• Nucleolus breakdown: The nucleolus, involved in rRNA synthesis, disintegrates and ceases to be visible as chromatin condenses.
• Nuclear envelope fragmentation: The membrane enclosing the nucleus breaks down into small fragments, enabling spindle fibers to access and interact with the chromosomes.

These events are essential for the subsequent stages of karyokinesis, which involve chromosome movement and segregation into new cells. The nuclear envelope and nucleolus are reconstituted towards the end of telophase as cell division approaches conclusion.