Tuesday, February 26, 2008

Cell Membrane

The animal cell membrane is bilayer

The cell membrane (also called the plasma membrane, plasmalemma or "phospholipid bilayer") is a semipermeable lipid bilayer found in all cells.

Cytoplasm is a gelatinous, semi-transparent fluid that fills most cells.
The cytoplasm has three major elements; the cytosol, organelles and inclusions. The cytosol is the gooey, semi-transparent fluid in which the other cytoplasmic elements are suspended. The cytoplasm holds organelles and protects them, such as the vacuole, endoplasmic recticulum, etc. Cytosol makes up about 70% of the cell and is composed of water, salts and organic molecules.

The cell membrane surrounds the cytoplasm of a cell and, in animal cells, physically separates the intracellular components from the extracellular environment, thereby serving a function similar to that of skin.

The barrier is selectively permeable and able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival. The movement of substances across the membrane can be either passive, occurring without the input of cellular energy, or active, requiring the cell to expend energy in moving it. The membrane also maintains the cell potential.

A bilayer like a protective circle - life can start a new step.

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