Question

Which of the following is the correct sequence of stages in mitosis?

• A. Prophase $\rightarrow$ Metaphase $\rightarrow$ Anaphase $\rightarrow$ Telophase
• B. Metaphase $\rightarrow$ Prophase $\rightarrow$ Telophase $\rightarrow$ Anaphase
• C. Anaphase $\rightarrow$ Metaphase $\rightarrow$ Prophase $\rightarrow$ Telophase
• D. Telophase $\rightarrow$ Anaphase $\rightarrow$ Metaphase $\rightarrow$ Prophase

Hint:

Use the mnemonic: Please Make Another Two. (Prophase, Metaphase, Anaphase, Telophase).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Mitosis is the process of equational division where a eukaryotic cell replicates its DNA and divides into two genetically identical daughter cells.
This phase, known as the M-phase, is divided into karyokinesis (division of the nucleus) and cytokinesis (division of the cytoplasm).
Karyokinesis follows a strict, logical sequence to ensure error-free distribution of chromosomes.
Step 2: Detailed Explanation:
The stages of mitosis are defined by the specific behavior and position of the chromosomes:
1. Prophase: This is the initiation stage. Chromatin fibers condense to form distinct chromosomes. The nuclear envelope and nucleolus disappear. Centrosomes move to opposite poles and start forming the mitotic spindle.
2. Metaphase: The spindle fibers (microtubules) attach to the kinetochores of the sister chromatids. The chromosomes are aligned at the "metaphase plate" or the equator of the cell. This is the best stage to study chromosome morphology under a microscope.
3. Anaphase: The centromeres of each chromosome split simultaneously. The sister chromatids, now referred to as daughter chromosomes, are pulled toward opposite poles by the shortening of spindle fibers. This ensures each pole gets an identical set of genetic material.
4. Telophase: The chromosomes reach the poles and begin to de-condense back into chromatin. The nuclear envelope reforms around each set, and the nucleolus reappears. The spindle apparatus is disassembled.
Following these stages, cytokinesis occurs, physically splitting the cell into two.
Sequence (b), (c), and (d) are incorrect as they do not follow the physiological progression of the cell cycle.
Step 3: Final Answer:
The logical and biological order of mitosis is Prophase, followed by Metaphase, then Anaphase, and finally Telophase.