Protoplast

Encyclopedia : P : PR : PRO : Protoplast

Protoplast, from the ancient Greek πρωτον (first) + πλασσειν (to mould), initially referred to the first organized body of a species. This meaning is similar to the non-biological definition, the first from which all subsequent forms are derived.

Subsequently it has several biological definitions:

A protoplast is a plant, bacterial or fungal cell that has had its cell wall completely or partially removed using either mechanical or enzymatic means. Generally this is accomplished with cell wall degrading enzymes. In this case there are two types generally recognized:
*Protoplasts - Have their cell wall entirely removed
*Sphaeroplasts - Have their cell wall only partially removed

More generally a protoplast refers to that unit of biology which is composed of a cells nucleus and the surrounding protoplasmic materials.

Enzymes for the preparation of protoplasts

Cell wall are made from a variety of polysaccharides, protoplasts can be made by degrading cell walls with a mixture of the appropriate polysaccharide degrading enzymes.

Type of cell	Enzyme
Plant cells	Cellulase, pectinase, xylanase
Gram-positive bacteria	Lysozyme (+EDTA)
Fungal cells	Chitinase

Following the digestion of the cell wall the protoplast is very sensitive to osmotic stress, and must be stored in an isotonic solution to prevent rupture.

Uses for protoplasts

Protoplast can be used to study membrane biology, including the uptake of macromolecules and viruses.

Protoplasts are widely used for DNA transformation (for making genetically modified organisms), or for studying temporal gene expression. Protoplasts may be regenerated into whole plants using Micropropagation, a modern technique employing plant tissue culture methods.

Protoplasts may also be used for plant breeding, using a technique called protoplast fusion. Protoplasts from different species are forced to fuse by using an electric field or a solution of polyethylene glycol. This technique may be used to generate hybrids in tissue culture.

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.