Mitosis
Mitosis
Mitosis is the process where a cell divides, to create two diploid cells identical to the first other than for a small bit of protein that lets the cell know how many times it has divided.
1. The cell duplicates its chromosomes so that it now has double as many, but they remain attached.
2/3. The cell begins to split until it has the chromosomes have separated completely, to form two separate set of chromosomes. The cell begins to divide.
4. The cell divides completely to form two diploids (cells with all 46 chromosomes).
When It Goes Wrong
Although errors in mitosis are rare, the process may go wrong, especially during early cellular divisions in the zygote. Mitotic errors can be especially dangerous to the organism because future offspring from this parent cell will carry the same disorder.
In nondisjunction, a chromosome may fail to separate during stage 2. One daughter cell will receive both sister chromosomes and the other will receive none. This results in the former cell having three chromosomes containing the same genes (two sisters and a homologue), a condition known as trisomy, and the latter cell having only one chromosome (the homologous chromosome), a condition known as monosomy. These cells are considered aneuploid, a condition often associated with cancer.
Mitosis is a demanding process for the cell, which goes through dramatic changes in ultrastructure, its organelles disintegrate and reform in a matter of hours, and chromosomes are jostled constantly by probing microtubules. Occasionally, chromosomes may become damaged. An arm of the chromosome may be broken and the fragment lost, causing deletion. The fragment may incorrectly reattach to another, non-homologous chromosome, causing translocation. It may reattach to the original chromosome, but in reverse orientation, causing inversion. Or, it may be treated erroneously as a separate chromosome, causing chromosomal duplication. The effect of these genetic abnormalities depends on
Mitosis is the process where a cell divides, to create two diploid cells identical to the first other than for a small bit of protein that lets the cell know how many times it has divided.
1. The cell duplicates its chromosomes so that it now has double as many, but they remain attached.
2/3. The cell begins to split until it has the chromosomes have separated completely, to form two separate set of chromosomes. The cell begins to divide.
4. The cell divides completely to form two diploids (cells with all 46 chromosomes).
When It Goes Wrong
Although errors in mitosis are rare, the process may go wrong, especially during early cellular divisions in the zygote. Mitotic errors can be especially dangerous to the organism because future offspring from this parent cell will carry the same disorder.
In nondisjunction, a chromosome may fail to separate during stage 2. One daughter cell will receive both sister chromosomes and the other will receive none. This results in the former cell having three chromosomes containing the same genes (two sisters and a homologue), a condition known as trisomy, and the latter cell having only one chromosome (the homologous chromosome), a condition known as monosomy. These cells are considered aneuploid, a condition often associated with cancer.
Mitosis is a demanding process for the cell, which goes through dramatic changes in ultrastructure, its organelles disintegrate and reform in a matter of hours, and chromosomes are jostled constantly by probing microtubules. Occasionally, chromosomes may become damaged. An arm of the chromosome may be broken and the fragment lost, causing deletion. The fragment may incorrectly reattach to another, non-homologous chromosome, causing translocation. It may reattach to the original chromosome, but in reverse orientation, causing inversion. Or, it may be treated erroneously as a separate chromosome, causing chromosomal duplication. The effect of these genetic abnormalities depends on