Membrane-transport-system | Notes-by-UK-Sir | Cell-Bio-7
CELL (Cell Biology)
Membrane Transport:
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| Transport Type |
As the Plasma membrane is selectively permeable, there are various
type of transport system can be seen. They are of following types:
1.
Passive Transport:
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Do not need any kind of energy for transport of material.
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Mostly transport occurs from high conc. Area to
low conc. Area.
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Transport mainly dependent on simple diffusion
or Osmosis process.
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Diffusion occurs directly or through the Channel
and Carrier proteins(Facilitated diffusion)
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Neutral Solutes or Lipid soluble substances can
directly pass through membrane.
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There are some open channel protein and Ion
channels for facilitated diffusion.
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Presence of Aqua porins for water
transport.
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| Passive Transport |
2.
Active Transport:
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In Active transport there is use of Energy.
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Here the transport of material occurs from lower
conc. To Higher conc. i.e. against the Osmosis law.
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Active transport is of two type
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A)Primary active transport: Direct use of ATP as
energy source
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B)Secondary Active transport: ATP is not used
directly. Other sources for energy.
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Primary Active transport- Example- H+ ATpase Present in
Mitochondria, Calcium pump ATpase in RBC
and Muscle cells.
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Secondary Active transport mostly done by
various carrier proteins, also called as pumps.
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| Types |
- Pumps are of 3 types- Uniport (1 molecule to onedirection at a time )
Symport (2 Molecule transport to the same direction)
Antiport (2 molecule transport to opposite direction)
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Uniport Pumps – K+/potassium Pump, Cl-
pump etc.
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Antiport Pump -
Sodium Potassium Pump, Na +
ca2+ exchanger in plasma membrane etc.
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Symport Pumps -
K+ H+ pump symporter in root, Na+ Cl – symporter, K+ Cl – symporter loop
of henle.
3.
Bulk Transport:
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When cell need material in Group/bulk/in Large
number, it perform bulk transport.
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It is of Two Type-
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A) Endo Cytosis: Inner ward transport of material
with help of Carrier Vesicle.
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B) Exo Cytosis: Outer ward transport of material
with help of Carrier Vesicle.
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Endo Cytosis is either -
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i) Phago Cytosis- Cell eating or ii) Pino Cytosis/
Poto Cytosis- Cell Drinking
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Sometime Receptor / Ligand mediated endocytosis
can be seen.
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| Endocytosis |
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