The Science of Mitotic Cell Division

What Is Mitosis?

Mitosis is a process of cell division that ensures genetic material remains unchanged.

Discovery of Mitosis

Mitosis was discovered in 1882 by Walther Flemming.

Main Features of Mitosis

• It is a type of cell division.
• It occurs in the somatic cells.
• It enables these cells to multiply.
• It produces two daughter cells that are identical to the parent cell after every mitotic division.
• Mitosis lasts about 2 hours.

Phases of Mitosis

Interphase: The duplication of chromatin occurs before cell division.

Prophase: Chromatin begins to condense and chromosomes become visible. In the cytoplasm, the spindle forms.

Metaphase: The chromosomes undergo a particular organization.

Anaphase: The microtubules begin to coil, the connection with the chromatids is broken, and single chromatids move to the opposite poles of the cell.

Telophase: The division of the nucleus is completed and it returns to the state in which it was during interphase.

The Cell Cycle

G1 phase: First growth phase. The cell doubles every single one of its components (2-4 hours).

Synthesis phase: DNA replication (8-10 hours).

G2 phase: Second growth phase. Prepares the cell for division (mitosis) (2-4 hours).

M phase: Cell growth and protein production stops. Cell division happens (2 hours).

Stages of Karyokinesis

Karyokinesis is the division of a cell nucleus into two daughter nuclei, each with an identical complement of chromosomes.

Early prophase: Chromatin begins to condense.

Late prophase: Each chromosome assumes the form of sister chromatids. The nucleolus disappears and the nuclear envelope disintegrates.

Metaphase: Fibers enter the nuclear area.

Anaphase: The paired chromatids of each chromosome separate and move towards the spindle poles. Anaphase is the shortest phase of mitosis.

Telophase: The chromatids reach the spindle poles.

Cytokinesis

Starts in late Anaphase, or at the very beginning of Telophase.

The final stage of the cell cycle: separates the two nuclei into two daughter cells. It begins by splitting the equator of the cell.

• Animal cell: A cleavage furrow separates the daughter cells.
• Plant cell: A cell plate, which becomes a new cell wall, separates the daughter cells. Only one specialized type of cell is capable of mitosis (meristematic cells).

Cytokinesis often fails to occur.