Where are genes located: MITOSIS

CELL DIVISION

Formation of daughter cells from the pre existing mother cells is known as cell division.

Two types of cell divisions are:

MITOSIS
MEIOSIS

Mitosis:

In the year 1882, WELTHER FLEMING, discovered the process of mitosis. In which he discovered that the cell division in mitosis happens only in somatic cells or we can say that mitosis is the cell divisions which is being done for the regeneration of the body parts.

They produce identical cells that is they have the same number of chromosomes.

NOTE:

There are same number of chromosomes in the somatic cells.

Mitosis have 4 stages or the mitotic phase begins that is after the G2 phase of interphase:

PROPHASE
METAPHASE
ANAPHASE
TELOPHASE

There is one more additional phase called cytokinesis.

PROPHASE: It is the initial stage of cell division, and also the longest stage.

This phase is divided into 3 phases:

Early phase: In this phase the chromatin materials condenses and becomes thick and short to form chromosomes. Nucleus becomes spheroidal, that is almost circular in shape. The protein used to condense the chromatin materials is known as condensins.
Mid phase: In this phase the nucleolus starts to disappear and nuclear membrane starts to break down.
Late phase: In this phase the cell organelles starts to disappear. Centrosomes each with a pair of centrioles moves apart to opposite poles and start forming spindle fibers between them.
Interphase

SPINDLE FIBER STARTS TO APPEAR AND THE CHROMATIN MATERIALS CONDENSES TO FORM THE CHROMOSOMES.

METAPHASE: Micro tubules of the spindle fibers interact with the chromosomes, this causes the chromosomes to align at the middle of the cell or the equatorial plate. Sister chromatids of the chromosomes are held at the centomere confirming the presence the protein structures called kinetochores (holds the chromosomes and attaches it with the spindle) at the surface.

ALIGNMENT OF THE CHROMOSOMES AT THE EQUATORIAL PLATE

ANAPHASE: Sister chromatids separates at the kinetochores and the daughter chromosomes along with that centomere moves towards the centrioles as the micotubules shorten. When all the chromosomes are separated at two sets one at each poles, anaphase is said to be completed.

SISTER CHROMATIDS SEPARATED

TELOPHASE: During this the daughter chromosomes arrive at the poles and the chromatin starts to decoil and the nucleoli reappears with the nuclear membrane and the cleavage furrow starts to appear.

CLEAVAGE FURROW STARTS TO APPEAR

CYTOKINESES: In animal cells cleavage furrow deepens and divides the cells into 2 daughter cells each containing a nucleus.

CELLS DIVIDED INTO 2 IDENTICAL DAUGHTER CELLS

IN PLANT CELLS:

New cell wall formation is triggered at the center of the cell by the formation of a cell plate, the cell plate grows outwards till it meets the existing walls resulting into 2 daughter cells.