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

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

Solution:

The disappearance of the nucleolus and the nuclear envelope occurs during prophase of karyokinesis.

Explanation:

In prophase, the early phase of mitosis or meiosis, several key events take place:

• Chromatin condensation: The chromatin fibers begin to condense into distinct chromosomes that are visible under a microscope.
• Disappearance of the nucleolus: The nucleolus, which is responsible for ribosomal RNA production, disassembles and becomes invisible as the chromatin condenses.
• Disintegration of the nuclear envelope: The nuclear envelope, which surrounds the nucleus, begins to break down into vesicles, allowing the spindle fibers to interact with the chromosomes.

These processes are crucial for the subsequent steps of karyokinesis, where the chromosomes will be moved and separated into daughter cells. The nuclear envelope and nucleolus reassemble later in telophase when the division is nearing completion.