Question

Background on cell division in plants: Why is cell division a regulated process? What is known about division plane orientation in plants? Please explain in detail not wikipedia! I'll upvote

Answer 1

Cell division is a regulated process. This is because of the following reasons:

The cell cycle is the cell’s way of replicating itself in an organized, step-by-step fashion.

Tight regulation of this process ensures that a dividing cell’s DNA is copied properly, any errors in the DNA are repaired, and each daughter cell receives a full set of chromosomes.

The cycle has checkpoints (also called restriction points), which allow certain genes to check for problems and halt the cycle for repairs if something goes wrong.

Cytokinesis or division plane orientation in plants:

Cytokinesis occurs by a special mechanism in plant cells, where the cytoplasm is partitioned by the construction of a new cell wall, the cell plate, inside the cell.

Cytoskeleton framework determines the plane of plant cell division. Array of microtubules appears in the G2 phase and forms a ring around the the entire cell just beneath the plasma membrane. It is called the pre-prophase band.

It also contains actin filaments in addition to microtubules. The microtubule disappears before metaphase, but actin filaments remain and provide a memory of the predetermined division plane.

The polar spindle microtubules assemble in this plane and form a cylinder- like structure called phragmoplast. Small membrane bound vesicles derived from the Golgi apparatus and filled with the cell walled precursors associate with the phragmoplast and fuse to form the early cell plate.

The polysaccharide molecule delivered by these vesicles form the matrix polysaccharide. Later, cellulose microfibrils are laid down within the cell plate to complete the new cell wall.

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