Mitosis: prophase, metaphase, anaphase and telophase

CELL DIVISION

Once each chromosome has been replicated to form the two chromatids, in many cells, mitosis follows automatically within 1 or 2 hours

PROPHASE

ANAPHASE

METAPHASE

PROMETAPHASE

The spindle is forming, the chromosomes of the nucleus, become chromosomes condensed

The growing microtubular spines of the aster fragment the nuclear envelope.

multiple microtubules from the aster attach to the chromatids at the centromeres, where the paired chromatids are still bound to each other; the tubules then pull one chromatid of each pair toward one cellular pole and its partner toward the opposite pole.

Two asters of the mitotic apparatus are pushed farther apart.

Occur because the micro- tubular spines from the two asters, where they interdigitate with each other to form the mitotic spindle, actually push each other away.

The chromatids are pulled tightly by their attached microtubules to the very center of the cell, lining up to form the equatorial plate of the mitotic spindle.

The two chromatids of each chromosome are pulled apart at the centromere.

All 46 pairs of chromatids are separated, forming two separate sets of 46 daughter .Two asters of the mitotic apparatus are pushed farther apart.

One of these sets is pulled toward one mitotic aster and the other toward the other aster as the two respective poles of the dividing cell are pushed still farther apart.

TELOPHASE

the two sets of daughter chromosomes are pushed completely apart. Then the mitotic apparatus dissolutes, and a new nuclear membrane develops around each set of chromosomes. This membrane is formed from portions of the endoplasmic reticulum that are already present in the cytoplasm

the cell pinches in two, midway between the two nuclei. This is caused by formation of a contractile ring of micro filaments composed of actin and probably myosin (the two contractile proteins of muscle) at the juncture of the newly developing cells that pinches them off from each other.