Before I begin with the description of the process, I would like to introduce a few general terms.
Homologous Chromosomes: This refers to the same type of chromosomes, i.e. the chromosomes responsible for the same characteristics, that pair up (one maternal and one paternal) inside the cell during meiosis. E.g.- X and Y chromosomes
Cytokinesis: It is the process by which the cytoplasm of a single eukaryotic cell divides to form two daughter cells during cell division.
Centromere: It is the structure in a chromosome which holds the two sister chromatids (replicated copies of chromosomes) together.
Kinetochore: It is a special structure formed only during cell division. It is a protein structure which assembles at the centromere and link the chromosomes to the microtubule polymers of the mitotic spindle.
I shall not mention the names of all the phases involved as I consider understanding of the process more important.
Prior to mitosis, the DNA in the cell replicates and proteins forming the mitotic spindle are synthesized.
Mitosis:
This is the process by which normal body cells divide. It is basically a nuclear process(takes place inside the nucleus). The following steps are involved:
1. The DNA condenses and the chromatin material organizes to form chromosomes. Nucleolus disappears.
2. The centriole divides and moves to the poles. Nuclear membrane disintegrates.
3. Fibers, called mitotic spindles emerge from the centrioles and some of these connect to the centromere of each chromosome forming kinetochores.
4. Chromosomes move to the equatorial plate of the cell.
5. The spindle fibers attached to the kinetochores begin to contract pulling the chromatids apart while the unattached fibers elongate.
6. The chromatids, now called chromosomes reach the poles of the cell as the unattached fibers continue to elongate.
7. Nuclear membrane develops at both ends, nucleoli reappear and the DNA unwinds.
8. A cleavage furrows through the top and bottom which divides the cell into two daughter cells.(cytokinesis)
With this we come to the end of mitosis. I shall discuss meiosis in my next post.
Homologous Chromosomes: This refers to the same type of chromosomes, i.e. the chromosomes responsible for the same characteristics, that pair up (one maternal and one paternal) inside the cell during meiosis. E.g.- X and Y chromosomes
Cytokinesis: It is the process by which the cytoplasm of a single eukaryotic cell divides to form two daughter cells during cell division.
Centromere: It is the structure in a chromosome which holds the two sister chromatids (replicated copies of chromosomes) together.
Kinetochore: It is a special structure formed only during cell division. It is a protein structure which assembles at the centromere and link the chromosomes to the microtubule polymers of the mitotic spindle.
I shall not mention the names of all the phases involved as I consider understanding of the process more important.
Prior to mitosis, the DNA in the cell replicates and proteins forming the mitotic spindle are synthesized.
A simplified diagram representing mitosis
Mitosis:
This is the process by which normal body cells divide. It is basically a nuclear process(takes place inside the nucleus). The following steps are involved:
1. The DNA condenses and the chromatin material organizes to form chromosomes. Nucleolus disappears.
2. The centriole divides and moves to the poles. Nuclear membrane disintegrates.
3. Fibers, called mitotic spindles emerge from the centrioles and some of these connect to the centromere of each chromosome forming kinetochores.
4. Chromosomes move to the equatorial plate of the cell.
5. The spindle fibers attached to the kinetochores begin to contract pulling the chromatids apart while the unattached fibers elongate.
6. The chromatids, now called chromosomes reach the poles of the cell as the unattached fibers continue to elongate.
7. Nuclear membrane develops at both ends, nucleoli reappear and the DNA unwinds.
8. A cleavage furrows through the top and bottom which divides the cell into two daughter cells.(cytokinesis)
With this we come to the end of mitosis. I shall discuss meiosis in my next post.
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