The fluid mosaic model proposes that the plasma membrane of animal cells is composed of a fluid bilayer of phospholipids within which proteins float. This model was developed in 1972 by S.J. Singer and Garth L. Nicolson. The phospholipids form a bilayer with hydrophilic heads facing out and hydrophobic tails in the middle. Cholesterol is found between the phospholipids and helps regulate fluidity. Integral proteins span the membrane while peripheral and glycoproteins are embedded within or attached to the external surface. This structure allows the membrane to regulate molecules moving in and out of cells while maintaining fluidity.

1. FLUID MOSAIC MODEL
• S. J. SINGER and GARTH L. NICOLSON
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2. DEFINITION
Fluid mosaic model is a model
that explain the structure of plasma
membrane of animal cells.
It was proposed by S. J. Singer
and Garth L. Nicolson in 1972.

3. SIGNIFICANT OF NAME
If we zoom in on the cell membrane we should see a pattern of different
types of molecules put together, also known as a ‘mosaic’. These molecules are
constantly moving in two dimensional way, in a fluid fashion, similar to icebergs
floating in the ocean. Because of this it is called ‘Fluid Mosaic Model‘.

4. PLASMA MEMBRANE
• Ernest Overton first proposed the concept
of a lipid plasma membrane on 1899.
• It is a microscopic membrane of lipit and
protein.
• Is the external boundary of cytoplasm
and regulates the passage of molecules
in and out of the cytoplasm.
• Is describe by ‘Fluid Mosaic Model’.

5. COMPOSITION
• Phospholipid ------- The main fabric of plasma membrane.
• Cholesterol ------- Between phospholipids and phospholipids bilayers.
• Protein ------- Inner or outer surface or embedded within
• phospholipids bilayers.
• Carbohydrate ------- Bound to glycolipids Or glycoproteins.

6. PHOSPHOLIPIDS
• The main fabric of plasma membrane.
• Consist of fatty acids and alcohol.
• Arranged by two layers, is called phospholipid bilayers.
• Has two parts – hydrophilic heads and hydrophobic tails.

7. PARTS OF PHOSPHOLIPIDS
1. Hydrophilic heads : water-loving polar group. Negetive charged making the
head polar and hydrophilic. Attract water to the cell membrane.
2. Hydrophobic tails : water-hating fatty acid chains. Carbon and hydrogen atoms
making the tail hydrophobic. Determine the properties of the membrane.

8. CHOLESTEROL
• Present between the phospholipids.
• Compression of hydrophilic heads at low temperture. ature.
• Expansion of hydrophilic heads at hight temperture. ature.
• Help in regulating molecules entering and exiting the
the cell.
• Help the plasma membrane to retain the fluidity.

9. PROTEIN
• Embedded orinner or outer surface of the phospholipid bilayers.
• Three types- 1. Integral protein, 2. Peripheral protein, 3. Glycoproteins
1. Intregral protein: Enter deeply into the layer. Allow the movement of large molecules and ions
across the hydrophobic layer.
2. Peripheral protein: Inner or outer surface of the layer. Carry signals from one segment of the
membrane and relay it to others.
3. Glycoprotein: Outer surface of the layer where carbohydrates are attached. Stabilize the
membrane and responsibile for intercellularcommunication.

10. CARBOHYDRATE
• Attached to proteins on outside membrane layer.
• Serve as points of attachment for other cells
• Help in cell adhesion and recognition.
• Act as physical barriers.

11. THANK YOU
Presented by ANUSHREE MAITY