Cell division

The phase between two mitoses is called INTERPHASE, during which the nucleus appears as it is normally observed in microscopic preparations.

The PROPHASE of mitosis is characterized by the gradual coiling of nuclear chromatin (uncoiled chromosomes), giving rise to several individual rod-or hairpin-shaped bodies (coiled chromosomes) that stain intensely.

During METAPHASE, chromosomes, due to the activity of microtubules, migrate to the equatorial plane of the cell, where each divides longitudinally to form two chromosomes called sister chromatids. The chromatidsattach to the microtubules of the mitotic spindle.

In ANAPHASE, the sister chromatidsseparate from each other and migrate toward the opposite poles of the cell, pulled by microtubules. Throughout this process, the centromeresmove away from the center, pulling the remainder of the chromosome along. The centromereis the constricted region of a mitotic chromosome that holds the two sister chromatidstogether until the beginning of anaphase.

TELOPHASE is characterized by the reappearance of nuclei in the daughter cells. The chromosomes revert to their semidispersedstate, and the nucleoli, chromatin, and nuclear envelope reappear. While these nuclear alterations are taking place, a constriction develops at the equatorial plane of the parent cell and progresses until the cytoplasm and its organelles are divided in two. This constriction is produced by microfilaments of actinassociated with myosin that accumulate in a beltlikeshape beneath the cell membrane.











G1 PHASE

The first phase within interphase, from the end of the previous M phase until the beginning of DNA synthesis is called G1 (G indicating gap). It is also called the growth phase. During this phase the biosynthetic activities of the cell, which had been considerably slowed down during M phase, resume at a high rate. This phase is marked by synthesis of various enzymes that are required in S phase, mainly those needed for DNA replication. Duration of G1 is highly variable, even among different cells of the same species.



S PHASE

The ensuing S phase starts when DNA synthesis commences; when it is complete, all of the chromosomes have been replicated, i.e., each chromosome has two (sister) chromatids. Thus, during this phase, the amount of DNA in the cell has effectively doubled, though the ploidyof the cell remains the same. Rates of RNA transcription and protein synthesis are very low during this phase. An exception to this is histoneproduction, most of which occurs during the S phase.



G2 PHASE

The cell then enters the G2 phase, which lasts until the cell enters mitosis. Again, significant protein synthesis occurs during this phase, mainly involving the production of microtubules, which are required during the process of mitosis. Inhibition of protein synthesis during G2 phase prevents the cell from undergoing mitosis.


MITOSIS (M PHASE)

The relatively brief M phase consists of nuclear division (karyokinesis) and cytoplasmicdivision (cytokinesis)

G0 PHASE:

In cells that are not continuously dividing, the activities of the cell cycle may be temporarily or permanently suspended. Cells in such a state (eg, muscle, nerve) are referred to as being in the G0phase.

CLINICAL :Growth factors stimulates increase cell cycle rate thus increase the cell production e.g.. Erythropoietin.In Cancers the cell cycle is abnormally increased thus uncontrolled cell production.Some Anticancer drugs act by controlling this uncontrolled rate.

4 comments:

  1. Cellular split is the procedure by which a mother or father cell breaks into two or more child tissue. Cellular split is usually a small part of a bigger cell period.

    ReplyDelete
  2. mbbs in Philippines
    Every year, almost 8000 foreign students take admission in Philippines Medical universities and out of which around 50% are Indian students. The standard of education in Philippines universities is well known around the world. Thousands of doctors from these medical universities are sent to various countries like USA and UK every year. There are around 2299 higher educational institutions and 40 medical colleges. The main benefits of pursuing MD degree from

    Top Medical Colleges in Philippines :

    EMILIO AGUINALDO COLLEGE OF MEDICINE
    UNIVERSITY OF PERPETUAL HELP SYSTEM DALTA
    LYCEUM NORTHWESTERN UNIVERSITY
    DAVAO MEDICAL SCHOOL FOUNDATION
    SOUTHWESTERN UNIVERSITY

    Top Searched Topics on MBBS in Philippines


    study mbbs in philippines
    philippines medical colleges list
    best medical colleges in philippines for indian students
    philippines medical colleges
    best medical colleges in philippines
    mci approved medical colleges in philippines

    for more information contact us : +91 90329 55688

    ReplyDelete
  3. UV GULLAS COLLEGE OF MEDICINE is one of Top Medical College in Philippines in Cebu city. International students have the oppertunity to study medicine in phillipines at affordable cost and world class University. The college has successful alumni who have achieved well in the fields of law, business, politics, academe, medicine, sports and other endeavors. At University of the Visayas, we prepare students for a global competition.

    Direct MBBS Admissions Open: 2020-21
    Mobile No: +91 90329 55688
    Apply Now: https://www.careerplus.org.in/philippines-medical-college/uv-gullas-college-of-medicine

    ReplyDelete

Popular Posts