What is a Plasma membrane?

The plasma membrane's the outer covering of the cytoplasm of the cell.

It acts as a selective filter and controls the entrance and exit of molecules and ions and,

thus helps maintain the difference in the ionic concentration in the cytoplasm and its surrounding.

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Ultrastructure of the plasma membrane?

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The plasma membrane is about 75 angstroms thick, But its thickness varies in different types of cells and ranges from 75 to 105 Angstroms or up to 215 angstroms.

Under the electron microscope, 3 distinct layers could be differentiated in the plasma membrane.

1. How to have a dense layer of protein:  about 20 to 25 Angstroms. 2. Middle bimolecular layer Of Lipids: about 30 - 35 Angstroms....