TR3.5

Mitosis

Houjun Liu 2021-09-27 Mon 12:00

1 Mitosis

Mitosis is the process by which somatic cells (not sperm/egg) replicate itself — by duplicating its DNA and splitting itself into two cells. The process of mitosis happens in 4ish stages. Basically:

  • (P)rophase — nucleus break down and DNA becomes bundled into chromosomes. The mitotic spindles began to form that will help pull the DNA away.
  • (M)etaphase — capturing of bundled chromosomes to line them up along the metaphase plate at the equator. The kineticore (center) of the chromosome become attached to the mitotic spindles in preparation for the anaphase.
  • (A)naphase ("a for away") — the microtubuals push poles apart and yank chromasomes by their kineticore to opposite ends of the poles. Kinetore senses tension, and when it is correct, molecules are sent down the microtubials to send a split signal
  • (T)elophase — the spindle disappears and the microtubuals break to form the cell wall of the two new cells. The chromasomes fall apart and the newly tangled bundle of DNA becomes encircled by the new nucleaus.
  • Cytokinesis — the two new cells seperate

1.1 Prophase

The cytoskeleton of a cell disassembles, and the spindles to seperate the cell begins to form.

The centrioles, the proteins connecting all the spindles, separate to opposite poles of the cell and establishes the bridge of all the microtubuels called the "spindle apparatus".

Protein "joints" in the centromeres of chromasomes called kineticore attach to a spindle after the nuclar envelope erupts.

1.2 Metaphase

The microtubuals guide the proteins to align in the equator of the cell called the "metaphase plate".

Organelles are also moved by being pulled by the motor proteins and their spindles.

1.3 Anaphase

The centromere's centre degrades, freeing the two halfs of the chromasomes.

Kinetore senses tension, and when it is correct, molecules are sent down the microtubials to send a split signal. Yanked by their kineticores by the microtubuals, each copy of the chromatid moves towards one pole of the cell.

1.4 Telophase

A "cleavage furrow" forms in the centre of the cell created by actin on the circumference constricting. As this cleavage deepens (the actin constricting further), the chromasomes unravel whilst a new nuclear envelope forms.

The spindle apparutus now disassembles; the microtubuals are broken down further into monomers that will eventually construct the exoskeleton of the new cells.

1.5 Cytokinesis

In animals… the cleavage furrow deepends even more and extends to the point where the two cells fully seperate. In plants… because there's no actin fibers to constrict the cell wall (it's too hard), vescles between the new cells form that pads out the twe newly-formed cells called the "cell plate." During cytokinesis, the cell plate widens to the point where two cells seperate.