Mitosis is the process by which a eukaryotic cell divides into two cells and the number of chromosomes remains unchanged.
mitosis, cell division, division of the nucleus, chromosome, chromatin, diploid cell, diploid, interphase, somatic cells, chromatids, centromere, DNA, cytology, biology
Our somatic cells are diploid, they contain two copies of each chromosome, one comes from the mother, the other from the father. These chromosomes have two chromatids, as their DNA content duplicates before the cell divides. The DNA content of the two chromatids is identical. When a diploid cell is divided by mitosis, the resulting daughter cells are also diploid, but their chromosomes have only one chromatid. These chromatids break up and the DNA duplicates before the next mitosis. The chromosomes in the cell will have two chromatids and cell division starts again. During the process the number of chromosomes does not decrease, unlike in meiosis, during which haploid gametes are formed from diploid cells.
Mitosis consists of four phases. The first phase is the prophase: chromosomes are formed from the chromatin which consists of DNA and proteins. The centrosome duplicates and moves towards the opposite poles of the cell. In the metaphase the nuclear membrane breaks down, the spindle apparatus is formed. Then the chromosomes line up along the equatorial plane of the cell. In the anaphase chromosomes split into chromatids, forming chromosomes with one chromatid, which then move towards the opposite poles of the cell. In the telophase the cell splits, and the nuclear membrane is formed again, then the chromosomes break up. That is, during mitosis two diploid cells are formed from one diploid cell.
Certain cells in our bodies, such as nerve cells, are not able to divide. Others may be able to divide several times during our lives.
The cell cycle is a finely tuned process, disturbances may lead to uncontrolled cell growth and the formation of tumors.
Eukaryotic cells contain a number of organelles.
Our gametes are haploid cells produced from diploid cells by meiosis, a special type of cell division.
Eukaryotic cells with nuclei measuring only a few micrometers may contain nearly 2 meters (6.6 ft) of DNA, coiled multiple times.
This animation demonstrates the development of the human embryo and fetus.
Carrier of genetic information in cells.
This animation compares the life cycles of mosses and ferns, helping to understand the general life cycle of plants.