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A plant cell wall was first observed and named (simply as a "wall") by Robert Hooke in 1665. [3] However, "the dead excrusion product of the living protoplast" was forgotten, for almost three centuries, being the subject of scientific interest mainly as a resource for industrial processing or in relation to animal or human health.
The terminal cell elongates more than the deeper cells; then the production of a lateral bisector takes place in the inner fluid, which tends to divide the cell into two parts, of which the deeper one remains stationary, while the terminal part elongates again, forms a new inner partition, and so on.
Cellular compartments in cell biology comprise all of the closed parts within the cytosol of a eukaryotic cell, usually surrounded by a single or double lipid layer membrane. These compartments are often, but not always, defined as membrane-bound organelles. The formation of cellular compartments is called compartmentalization.
During cytokinesis in animal cells, a contractile ring made up of actin filaments forms, and this ring pinches to divide the cell into two daughter cells. [6] The cells are able to separate due to the formation of a cleavage furrow, which pinches in a centripetal fashion (from the outside of the cell towards the center of the cell). [6]
The cell plate that is formed during cell division itself develops into middle lamella or lamellum. The middle lamella is made up of calcium and magnesium pectates. [2] In a mature plant cell it is the outermost layer of cell wall. [3] [4] In plants, the pectins form a unified and continuous layer between adjacent cells.
The pit aperture is the opening at either end of the pit chamber. The pit membrane is the primary cell wall and middle lamella, or the membrane between adjacent cell walls, at the middle of the pit chamber. [2] The primary cell wall at the pit membrane may also have depressions similar to the pit depressions of the secondary layers.
Pigments that color the cell are sometime located in the cell sap. Vacuoles can also increase the size of the cell, which elongates as water is added, and they control the turgor pressure (the osmotic pressure that keeps the cell wall from caving in). Like lysosomes of animal cells, vacuoles have an acidic pH and contain hydrolytic enzymes.
Pectins may also be absent from the secondary wall, and unlike primary walls, no structural proteins or enzymes have been identified. [4] Because of the low permeability through the secondary cell wall, cellular transport is carried out through openings in the wall called pits. Wood consists mostly of secondary cell wall, and holds the plant up ...