Mitosis: The Process of Nuclear Division
This page focuses on mitosis, the process of nuclear division in eukaryotic cells. Mitosis is divided into four main phases: prophase, metaphase, anaphase, and telophase (often remembered by the acronym PMAT).
Prophase, the longest phase of mitosis, involves several critical events:
- Chromatin condenses into visible chromosomes, each consisting of two sister chromatids held together by a centromere.
- The nucleolus disappears.
- Spindle fibers form from centrioles (in animal cells) or without centrioles (in plant cells).
- Centrioles migrate to opposite poles of the cell.
Vocabulary: Kinetochore - A protein structure on the centromere where spindle fibers attach during cell division.
Plant cells undergo an additional stage called preprophase, where the nucleus moves to the center of the cell and a phragmosome forms to establish the plane of cell division.
Highlight: The accurate control of division planes in plant cells is crucial for the correct structure of plant tissues and organs.
Prometaphase follows, during which the nuclear membrane disintegrates and spindle fibers invade the center of the cell, attaching to the kinetochores of each chromatid.
In metaphase, the centromeres of chromosomes align along the metaphase plate or equatorial plane at the cell's center.
Example: The spindle fibers act like ropes, positioning the chromosomes precisely at the cell's equator during metaphase.
This detailed explanation of mitosis highlights the complexity of the cell division process in eukaryotes and the precise mechanisms that ensure accurate distribution of genetic material to daughter cells.
