Question

The longest phase of mitosis is
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

Answer 1

Hint: Mitosis is the type of cell division where a cell divides, by preserving the number of chromosomes in the two daughter cells, or simply, to generate two exact copies of itself. The whole process of Mitosis takes place in four different phases: Prophase, Metaphase, Anaphase, and Telophase.

Complete answer:
> Prophase- This phase marks the beginning of the cell division, where a lot of structures are broken down and some are formed. Prophase can be studied in further two stages-
Early prophase and Late prophase. The events of both are stated below:

- Early Prophase: The chromatin fibers start to condense.
The movement of centrioles can be observed in an animal cell (absent in a plant cell).
The mitotic spindle starts to appear.
The nucleolus starts to break down.
The nuclear membrane starts to degenerate.

- Late Prophase: The chromatin fibers condense further taking the shape of chromosomes.
The mitotic spindle continues to form and some even attach themselves to the chromosomes.
The nuclear membrane almost disappears releasing the chromosomes into the cytoplasm.

> Metaphase- The mitotic spindle starts capturing the chromosomes in such a way that they align themselves in the center of the cell, forming an equatorial plate also known as a metaphase plate. Every chromosome is now attached to the spindle fiber through its kinetochores on both the opposite poles.

> Anaphase- The sister chromatids are detached by the pulling force of spindle fiber (motor proteins play a significant part in the process) and are moved to the opposite poles. The spindle fibers that do not attach with any chromosome, extend and push the two poles apart.

> Telophase- This phase also is marked by the activities opposite to the Prophase. Like:
The chromosomes now de-condense to take back the form of chromatin fibers, two sets of nuclear material, or say nuclei are formed on each pole and the microtubules start to degenerate.

Now, going through all these processes, we saw that there were a lot of activities involved in Prophase. Also, it is divided into an early and late stage. So clearly, the longest phase of the Mitosis is Prophase.

Hence, the correct answer is option (A).

Note: These phases do not have a sharp boundary for their beginning and end, as there are overlapping events. But given the number of events taking place, and the time taken to prepare a cell for its division during Prophase is the maximum compared to all the other phases. It is also a point to be noted, that Anaphase is the shortest stage in Mitosis.