Question

The spindle apparatus is formed during which phase of mitosis

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

Hint:

To remember mitotic events in order: PMAT.
- Prophase: Preparation (spindle forms, chromosomes condense).
- Metaphase: Middle alignment.
- Anaphase: Apart movement.
- Telophase: Two new nuclei.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Mitosis is the process of nuclear division where replicated chromosomes are separated into two new nuclei.
The spindle apparatus is a dynamic microtubule-based structure responsible for segregating these sister chromatids.

Step 2: Detailed Explanation:
The assembly of the mitotic spindle apparatus begins during the very first stage of mitosis, which is Prophase.
During prophase, the centrosomes (which contain centrioles in animal cells) begin to migrate to opposite poles of the cell.
As they migrate, they organize and nucleate microtubules, projecting them outward to establish the mitotic spindle.
During prometaphase, these spindle microtubules attach to the kinetochores of the condensed chromosomes.
In Metaphase, the spindle apparatus is fully established, and chromosomes are aligned at the metaphase plate.
In Anaphase, the spindle fibers shorten to pull chromatids apart, and in Telophase, the spindle apparatus disassembles.
Thus, the formation of the spindle apparatus is initiated and significantly progresses during prophase.

Step 3: Final Answer:
The spindle apparatus is formed during the prophase of mitosis.