The plasma membrane is a thin, semi-permeable membrane that surrounds the cytoplasm of a cell. It is composed of phospholipids, proteins, cholesterol, and carbohydrates. The plasma membrane acts as a barrier that separates the cell's interior from its external environment. It functions as a gatekeeper, allows for compartmentalization within the cell, and enables cell-to-cell communication through surface receptors.

1. 7/2/2017
Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan)
mujahid.hussain7877@gmail.com
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2. WHAT IS PLASMA MEMBRANE?
•Plasma membrane is a thin semi- permeable membrane
that surrounds the cytoplasm of a cell.
•Cell membrane is a barrier that separates a cell from its
surrounding environment.
•This outer boundary of cell is also called plasma
membrane.
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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3. COMPOSITION OF PLASMA
MEMBRANE:
•It is composed of four different kinds of
molecules:
1.phospholipids 20-40%
2.proteins 60-80%
3.cholesterol
4.carbohydrates 50%
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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4. 7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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5. MODEL OF PLASMA MEMBRANE:
•Unit membrane model:
When lipid bilayer is sandwich between the
proteins it is called unit membrane model.
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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6. Fluid mosaic model:
Proteins molecules are embedded in lipid
layer it is called fluid mosaic model.
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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7. FUNCTIONS OF PLASMA
MEMBRANE:•Gate keeper-determines what can and
cannot get into the cell
•Compartmentalization – makes certain
process such as chemiosmosis and action
potential possible.
•Cell – to-cell communication and
recognition – surface receptor.
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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8. FUNCTIONS OF MEMBRANE
COMPONENTS:
• Membrane carbohydrates play a role in cell to cell
recognition.
• Membrane proteins have many functions
• transport
• Enzymatic
• Signal transduction
• Cell to cell recognition
• Cell to cel junctions
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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9. •Cholesterol reduces the fluidity of membrane.
7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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10. 7/2/2017Mujahid Hussain (Department of Botany, University of Sargodha, Sargodha, Punjab, Pakistan) mujahid.hussain7877@gmail.com
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