Cell Cycle and Mitosis

Learning the life cycle of a cell.

Cell Cycle

The cell cycle can be divided into different stages.

1. Interphase

2. M-Phase

Interphase

Interphase can be broken into these sub stages:

1. G1- Gap 1 phase. Cell does most of it's growing in this phase.

2. S-Phase-Synthesis phase. This is the most important step of interphase because this is when DNA replication occurs. DNA replication is the process in which DNA is going to make an exact copy of itself. This is important because the end product of mitosis is 2 identical diploid cells. In order for the cells to be identical, then the DNA has to be copied at some point in the cell cycle. The S-Phase is when that happens!

3. G2- Gap 2 phase. This is when the cell starts to duplicate the organelles that are essential for cellular division.

M-Phase

The M-Phase is the cellular division phase. It can be broken into two stages:

1. Mitosis- nuclear division

2. Cytokinesis- division of the cytoplasm

Mitosis

Mitosis can be divided into these four main stages (PMAT):

Prophase

Metaphase

Anaphase

Telophase

Prophase

Steps that happen during Prophase:

  1. Nuclear envelope begins to dissappear.
  2. Chromatin condenses into chromosomes.
  3. Centrioles start to move to opposite ends of the cell.
  4. Spindle fibers begin to form.

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Metaphase

Steps that happen during Metaphase:

1. Chromosomes line up in the middle of the cell.

2. The spindle fibers attach to the centromere (middle) of the chromosome.

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Anaphase

Steps that occur during anaphase:

1. Chromosomes will be pulled apart.

2. Sister chromatids will be pulled by shortening spindle fibers to opposite ends of the cell.

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Telophase

Steps that occur during telophase:

1. Nuclear membrane begins to reform.

2. Spindle fibers begin to break down.

3. Chromosomes begin to break back down into chromatin.


*When this stage is complete nuclear division is over. Cellular division still has to continue.

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Cytokinesis

Cytokinesis is the division of the cytoplasm. This has to happen in order for cellular division to finish. In animal cells a cleavage furrow is formed with the cytoplasm pinches off. In plant cells a cell plate is formed which will eventually become the new cell wall.
The Stages of Mitosism (HD)