JKSSB Notes PDF JKSSB Study Notes Science Biology PDF Download

JKSSB Notes PDF JKSSB  Download Link At End 

JKSSB Notes PDF JKSSB Study Notes Science Biology PDF Download  JKSSB 

Plasma Membrane or Cell Membrane

• Cell membrane is also called the plasmamembrane.

• It can be observed only through an electron microscope.

• Plasma membrane is the outermost covering of the cell that separates the contents of the cell from its external environment.


• The plasma membrane is flexible and is made up of organic molecules called lipids and proteins.

• The flexibility of the cell membrane also enables the cell to engulf in food and other material from its external environment. Such processes are known as endocytosis (endo → internal; cyto → of a cell). Amoeba acquires its food through such processes.


• Plasma membrane is a selectively permeable membrane [The plasma membrane is porous and allows the movement of substances or materials both inward andoutward].

• Some substances like carbon dioxide or oxygen can move across the cell membrane by a process called diffusion [spontaneous movement of a substance from a region of high concentration (hypertonic solution) to a region where its concentration is low (hypotonic solution)].

• Thus, diffusion plays an important role in gaseous exchange between the cells as well as the cell and its external environment.



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