The plasma membrane, also called the cell membrane, is found in all cells and separates the interior of the cell from the outside environment. It is composed of lipids, proteins, and carbohydrates arranged in a phospholipid bilayer. In prokaryotic cells, the plasma membrane surrounds the cytoplasm, while in eukaryotic cells it surrounds the cytoplasm and encloses organelles. The plasma membrane regulates what enters and exits the cell and maintains the integrity and shape of the cell.

1. PLASMA MEMBRANE
By,
S. Sachin,
BP221512,
I-M.Sc., Microbiology,
Sacred Heart College
(Autonomous), Tirupattur.

2. What is Plasma membrane ?
• The Plasma membrane, also called the Cell
membrane, is the membrane found in all cells that
separates the interior of the cell from the outside
environment.
• In bacterial and plant cells, a cell wall is attached to
the plasma membrane on its outside surface.

4. History
• The term ‘plasma membrane’ was coined by
C. Nageli and C. Cramer in 1855.
• In 1895, Charles Overton suggested that plasma
membrane is composed of lipids.
• In 1900-1920, further studies on plasma membrane
state that lipid must be a phospholipid.
• In 1925, E. Gorter and G. Grendel proposed that
plasma membrane is composed of phospholipid
bilayer.

5. Chemical Composition
• Plasma membrane consist of three major components:
1. Lipid
2. Protein
3. Carbohydrate
• For example, the plasma membrane of human RBC
contains:
• Protein – 52%
• Lipid – 40%
• Carbohydrate – 8%

6. Plasma membrane in Prokaryotic cell
• The prokaryotic cells have plasma membrane.
• It plasma membrane is a lipid bilayer that surrounds
the cytoplasm of a prokaryotic cell.
• It physically separates the cytoplasm from the outside
environment.
• The plasma membrane also works as a selectively
permeable, or semi permeable, barrier that controls
what enters and exits the cell.

8. Plasma membrane in Eukaryotic cell
• All eukaryotic cells have a surrounding plasma
membrane, which is also known as the cell
membrane.
• The plasma membrane is made up by a phopholipid
bilayer with embedded proteins that separates the
internal contents of the cell from its surrounding
environment.

9. Structure of Eukaryotic cell

10. Difference between prokaryotic and
eukaryotic plasma membrane
• In eukaryotic cells, which have a nucleus, the
cytoplasm is everything between the plasma
membrane and the nuclear envelope.
• In prokaryotes, which lack a nucleus, cytoplasm
simply means everything found inside the plasma
membrane.

11. Functions of plasma membrane
• Keeps a cell interact.
• Protective barrier.
• Regulate transport in & out of cell (selectively
permeable)
• Maintains integrity of the cell – size and shape
• Maintains the ionic concentration of the cell &
osmotic pressure of the cytosol.
• Sensitivity.
• Regulates biochemical reactions.

12. •Creates attachments within and between other
cells.
•Identification
•Regulation of solute exchange through the
membrane.
•Isolation of the cytoplasm from the extrnal
environment.

13. Thank you