Define Cell Membrane.

1.	Define Cell Membrane.
Answer» Cell Membrane : (a) Cell membrane is also called as plasma membrane or plasma lemma. (b) It is the limiting boundary of each cell which separates the cytoplasm from its surroundings. (c) It is found in both plant as well as animal cells. (d) It is the outermost covering of a cell in case of animals and lies below the cell wall in case of plants. (e) It is made up of proteins and lipids where proteins are sandwiched between bilayer of lipids. (f) Plasma membrane is selectively permeable in nature. It allows or permits the entry and exit of some materials in and out of the cell. (g) Singer and Nicholson gave the fluid mosaic model of plasma membrane. According to them, it consists of a protein layer sandwiched between two layers of lipids. It is in quasifluid state. It is 75A thick. (h) It is flexible and can be folded, broken and reunited.

Answer»

Cell Membrane :

(a) Cell membrane is also called as plasma membrane or plasma lemma.

(b) It is the limiting boundary of each cell which separates the cytoplasm from its surroundings.

(d) It is the outermost covering of a cell in case of animals and lies below the cell wall in case of plants.

(e) It is made up of proteins and lipids where proteins are sandwiched between bilayer of lipids.

(f) Plasma membrane is selectively permeable in nature. It allows or permits the entry and exit of some materials in and out of the cell.

(g) Singer and Nicholson gave the fluid mosaic model of plasma membrane. According to them, it consists of a protein layer sandwiched between two layers of lipids. It is in quasifluid state. It is 75A thick.

(h) It is flexible and can be folded, broken and reunited.

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