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Plasma Membrane
1 PPISMP SAINS 2014
By:
o Sabila
Plasma Membrane
• Biological membrane that encloses the
cytoplasm/protoplasm of the cell.
• Separate the interior and exte...
Structure of Plasma
Membrane
DANIELLI-DAVSON MODEL
• Proposed by Danielli & Davson in 1953.
• Made of phospholipid bilayer...
FLUID MOSAIC MODEL
• Also known as Singer Model.
• Proposed by S.Jonathan Singer & Garth Nicolson in
1972 based on their s...
• The membrane is a dynamic fluid system with
globular proteins embedded in the
phospholipid bilayer mosaic structure.
• P...
• Composed of 2 protein ; Integral & peripheral
proteins.
- Integral proteins > interspersed between
phospholipids.
> act ...
• Composed of carbohydrates [glycoproteins &
glycolipid]
- Glycoproteins ; formed when oligosaccharides
attached to globul...
• Composed of cholesterol – reduce the
membrane flexibility & permeability to the
substances.
- Increasing the fluidity.
•...
Functions of Plasma
Membrane
• Controls the inflow & out flow of materials to
maintain the internal environment of the cel...
Plasma membrane
Plasma membrane
Plasma membrane
Plasma membrane
Plasma membrane
Plasma membrane
Plasma membrane
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Plasma membrane

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The Structure and Functions of Plasma Membrane
by: Nur Sabila Mohamad

sabellamohamad@gmail.com

Published in: Education
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Plasma membrane

  1. 1. Plasma Membrane 1 PPISMP SAINS 2014 By: o Sabila
  2. 2. Plasma Membrane • Biological membrane that encloses the cytoplasm/protoplasm of the cell. • Separate the interior and external of the cell. • Provides shape & protection. • Semipermeable or selectively permeable. • Made of a phospholipid bilayer ; - Hydrophilic [water liking] face ouside. - Hydrophobic [water dreading] face inside.
  3. 3. Structure of Plasma Membrane DANIELLI-DAVSON MODEL • Proposed by Danielli & Davson in 1953. • Made of phospholipid bilayer where; - the hydrophilic [polar] heads facing outside & coated with protein. - Hydrophobic [non-polar] tails facing inwards, sandwiched between two bilayer. - Structure is stable, static & rigid.
  4. 4. FLUID MOSAIC MODEL • Also known as Singer Model. • Proposed by S.Jonathan Singer & Garth Nicolson in 1972 based on their study by using freeze-fracture technique. • In this model, membrane is a fluid system with proteins embedded in phospholipid bilayer. • Composed of : - 2 type of protein [ Integral & peripheral ] - Phospholipid - Cholesterol - 2 type carbohydrates [ glycoprotein & glycolipid ]
  5. 5. • The membrane is a dynamic fluid system with globular proteins embedded in the phospholipid bilayer mosaic structure. • Phospholipid move through the membrane and flip flopping across it fluidity • Protein do not coat the membrane surface. • Thickness of PM: 7.5 nm. • Phospholipid is the main component of PM.
  6. 6. • Composed of 2 protein ; Integral & peripheral proteins. - Integral proteins > interspersed between phospholipids. > act as enzymes, pumps, carriers, channels & receptors. - Peripheral proteins > attached to the inner or outer surface of the membrane.
  7. 7. • Composed of carbohydrates [glycoproteins & glycolipid] - Glycoproteins ; formed when oligosaccharides attached to globular proteins. - Glycolipid ; formed when oligosaccharides attached to phospholipids. • Both act as – chemical receptors - cell recognition that enable the cells to : (i) recognise each other. (ii) differentiate themselves from foreign cells.
  8. 8. • Composed of cholesterol – reduce the membrane flexibility & permeability to the substances. - Increasing the fluidity. • PM are semi permeable. • Small uncharged polar molecules are able to cross the PM freely. • Ions & large uncharged polar molecules such as glucose are not allowed.
  9. 9. Functions of Plasma Membrane • Controls the inflow & out flow of materials to maintain the internal environment of the cell. • Separate the cytoplasm from its external environment. • Act as cell identity marker provided by glycoprotein & glycolipids. • Act as receptor for chemicals. • Helps transporting ions and large, polar substances into & out of the cell. • Act as attachment site for cytoskeleton that maintain the cell shape. • Play a role in cell adhesion.

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