cell cycle - the time from one cell division to the next.Proceeds in two successive stages - the interphase and the actual division.The duration of this process differs depending on the type of cells.
Interphase is the period between the two cell divisions, the time of the last division to cell death or loss of the ability to divide.
In this period, the cells increases and doubles its DNA, as well as mitochondria and plastids.In interphase passes protein synthesis, and other organic compounds.The most intensive process of synthesis takes place in synthetic period of interphase.At this time, double nuclear chromatids accumulates energy that will be used during the division.Also, an increasing number of cell organelles and centrioles.
Interphase occupies almost 90% of the cell cycle.After it passes mitosis, which is the main way of dividing cells of eukaryotes (organisms whose cells contain a nucleus formed).At mitosis
chromosomes condense and form a special device which is responsible for uniform distribution of genetic information between cells that result from this process.
Cell division takes place in several stages.Mitosis and are characterized by the individual characteristics of a particular duration.
Phase of mitosis
during mitosis are appropriate phase of mitosis: prophase, after it goes metaphase, anaphase, telophase is final.
Phase of mitosis characterized by the following features:
- prophase - nuclear envelope disappears.In this phase, the centrioles to the poles disperse cells and chromosomes condense (sealed);
- metaphase - characterized by placing maximum contraction of chromosomes, which consist of two chromatids at the equator (middle) cell.This phenomenon is called the metaphase plate.It is shown, you can well see chromosomes under a microscope.In the metaphase of mitosis occurs also attach one end to the spindle threads centromeres of chromosomes, the other end - to centrioles.
- anaphase - shown is the separation of the chromosomes in the chromatids (they disperse to different poles).This chromatids become separate chromosomes, which consist of only one chromatid strands;
- telophase - characterized decondensation of chromosomes and the formation around each chromosome of a new nuclear envelope.Threads spindle disappear in the core of nucleoli appear.In telophase cytokinesis also takes place, which is a division of the cytoplasm between the daughter cells.This process is carried out in animals due to special cleavage furrow (constriction that divides the cell in two).In plant cells, the process of cytokinesis cell plate provided with the Golgi complex.
What is the biological significance of the process of mitosis?
Phase of mitosis contribute to the accurate transmission of genetic information to daughter cells, regardless of the number of divisions.In addition, each of them receives one chromatid that helps maintain consistency number of chromosomes in all cells that are formed by division.It transmits mitosis stable set of genetic material.