Mitosis how does it work

From Genetics Home Reference. Mitosis and meiosis, the two types of cell division. Topics in the How Genes Work chapter What are proteins and what do they do? How do genes direct the production of proteins? Can genes be turned on and off in cells? What is epigenetics? How do genes control the growth and division of cells? How do geneticists indicate the location of a gene? The mitotic spindle, consisting of the microtubules and other proteins, extends across the cell between the centrioles as they move to opposite poles of the cell.

Metaphase: The chromosomes line up neatly end-to-end along the centre equator of the cell. The centrioles are now at opposite poles of the cell with the mitotic spindle fibres extending from them. The mitotic spindle fibres attach to each of the sister chromatids.

Anaphase: The sister chromatids are then pulled apart by the mitotic spindle which pulls one chromatid to one pole and the other chromatid to the opposite pole. Telophase: At each pole of the cell a full set of chromosomes gather together. A membrane forms around each set of chromosomes to create two new nuclei. The single cell then pinches in the middle to form two separate daughter cells each containing a full set of chromosomes within a nucleus.

This process is known as cytokinesis. Related Content:. What is a stem cell? What is a cell? What is DNA? What is a chromosome? What is a genetic disorder? What is meiosis? Mitosis versus meiosis.

How helpful was this page? The mitotic spindle is flexible and is made of microtubules, which are in turn made of the protein subunit, tubulin. Metaphase: The nuclear membrane dissolves and the mitotic spindle latches on to the sister chromatids at the centromere. The mitotic spindle can now move the chromosomes around in the cell. They are structural elements that are extremely dynamic.

Anaphase: The mitotic spindle contracts and pulls the sister chromatids apart. They begin to move to opposite ends of the cell. Telophase: The chromosomes reach either end of the cell. The nuclear membrane forms again and the cell body splits into two cytokinesis.

The various events of the cell cycle are tightly regulated. If errors occur at any one stage, the cell can stop cell division from progressing. Such regulatory mechanisms are known as cell cycle checkpoints, according to Cooper. There are three checkpoints within the G1, G2 and M phases. Damaged DNA stops cell cycle progression in the G1 phase, ensuring that an aberrant cell will not be replicated.

The G2 checkpoint responds to incorrectly duplicated, or damaged DNA. It prevents cells from moving into the M phase until the DNA is replicated correctly, or until the damage is repaired.

The M phase checkpoint can halt the cell cycle in metaphase. It ensures that all the sister chromatids are properly hooked up to the mitotic spindle and that sister chromatids move towards opposite ends of the cell. That's usually a good thing. Sometimes, abnormal cells manage not only to survive, but also to proliferate. Most often, these cells are implicated in cancer. And that's going to start pushing the cell cycle forward when it shouldn't be going forward," Hoyt said. The relationship between the cell cycle and cancer has led to the development of a class of cancer drugs that specifically target cancer cells during mitosis.

For example, microtubule poisons stop mitosis by targeting microtubules , the main component of the mitotic spindle. Damaging these thin, hollow, microscopic protein filaments ultimately prevents sister chromatids from being pulled apart.

Examples of microtubule poisons are the medications paclitaxel Taxol and vinca alkaloids , which are used to treat a range of cancers, including certain ovarian and breast cancers.