MITOSI S
It is the type of cell division in which number, of chromosome remains some in
daughter cells as compared the parental cell.
In Plants and Animals:
In spite of slight differences, major of steps of mitosis are similar in plants as well
as in animals. The main events discussed are mainly based on the animal cells.
Occurrence:
Mitosis can takes place in diploid as well as haploid cells.
PHASES OF MITOSIS
Mitosis is a continuous process, but for the sake of convenience it may be divided
into two main phases:
1. Karykineisis: Which involves the division of nucleus.
2. Cytokinesis: that refers to the division of the whole cell.
1. KARYOKINESIS:
This is the first main process of the mitosis during which one nucleus divides into
two nucleoli through an intricate series of events.
Stages of Karyokinesis:
Karyokinesis can further be divided into four main phases, which are
(a) Prophase (b) Metaphase (c) Anaphase (d) Telophase.
During Interphase (Non – dividing) of the cell cycle the chromosomes are not
visible even with electron microscope, but using histological strains for DNA, network of
very fine threads can be visualized. This network is called as chromatin.
Prophase:
It is a lengthy phase and a large number of events take place during this phase.
Events:
1. At the beginning of the process, the partition of the centrioles take place which have
been duplicated during interphase but were in the same centrosome.
2. Early in the mitosis the two pairs of centrioles separate and migrate to opposite
sides of the nucleus, establishing the bipolarity (having two poles) of the dividing
cells.
3. The chromatin material gets condensed as a result of folding, coiling and super
coiling.
4. The chromosomes appear as thin threads 0.25 m – 50 m in length) at the
beginning of prophase. Chromosomes become more and more thick and their
visibility increases.
5. Each chromosome is already duplicated i.e., having two sister chromatids, attached
at centromere. A special base sequence and a protein part kinetochore is present at
the centromere.
6. Mitotic apparatus is formed during this phase.
MITOTIC APPARATUS
This is a specialized structure formed by various kinds of microtubules and two
pairs of centrioles. This structure is larger than the nucleus.
Three sets of microtubules (fibers) originate from each pair of centrioles. These
are:
It is the type of cell division in which number, of chromosome remains some in
daughter cells as compared the parental cell.
In Plants and Animals:
In spite of slight differences, major of steps of mitosis are similar in plants as well
as in animals. The main events discussed are mainly based on the animal cells.
Occurrence:
Mitosis can takes place in diploid as well as haploid cells.
PHASES OF MITOSIS
Mitosis is a continuous process, but for the sake of convenience it may be divided
into two main phases:
1. Karykineisis: Which involves the division of nucleus.
2. Cytokinesis: that refers to the division of the whole cell.
1. KARYOKINESIS:
This is the first main process of the mitosis during which one nucleus divides into
two nucleoli through an intricate series of events.
Stages of Karyokinesis:
Karyokinesis can further be divided into four main phases, which are
(a) Prophase (b) Metaphase (c) Anaphase (d) Telophase.
During Interphase (Non – dividing) of the cell cycle the chromosomes are not
visible even with electron microscope, but using histological strains for DNA, network of
very fine threads can be visualized. This network is called as chromatin.
Prophase:
It is a lengthy phase and a large number of events take place during this phase.
Events:
1. At the beginning of the process, the partition of the centrioles take place which have
been duplicated during interphase but were in the same centrosome.
2. Early in the mitosis the two pairs of centrioles separate and migrate to opposite
sides of the nucleus, establishing the bipolarity (having two poles) of the dividing
cells.
3. The chromatin material gets condensed as a result of folding, coiling and super
coiling.
4. The chromosomes appear as thin threads 0.25 m – 50 m in length) at the
beginning of prophase. Chromosomes become more and more thick and their
visibility increases.
5. Each chromosome is already duplicated i.e., having two sister chromatids, attached
at centromere. A special base sequence and a protein part kinetochore is present at
the centromere.
6. Mitotic apparatus is formed during this phase.
MITOTIC APPARATUS
This is a specialized structure formed by various kinds of microtubules and two
pairs of centrioles. This structure is larger than the nucleus.
Three sets of microtubules (fibers) originate from each pair of centrioles. These
are:
