Passive transport: Difference between revisions
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Passive transport is the movement of molecules across the [[ | Passive transport is the movement of molecules across the [[Plasma membrane|plasma membrane down]] the concentration gradient without the input of energy<ref>↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular biology of the cell, 5th edition, Garland science.</ref>, therefore the concentration determines the direction and rate of transport across the membrane. | ||
There are two types of passive transport: | There are two types of passive transport: | ||
*[[Simple diffusion|Simple diffusion]] - Non-polar, [[Water|water]], small, [[Hydrophobic|hydrophobic]] [[Molecules|molecules]] can cross the membrane by simple diffusion | |||
*[[Facilitated diffusion|Facilitated diffusion]] - Many [[Molecules|molecules]] ([[Polar|polar]], charged, large, and [[Hydrophilic|hydrophilic]]) can not cross the [[Plasma membrane|plasma membrane]], so the passage of these molecules is facilitated by membrane transport proteins (channel or carrier [[Proteins|proteins]]) <ref>↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular biology of the cell, 5th edition, Garland science.</ref>. An advantage of facilitated diffusion is that there is potential for movement across the membrane in either direction of the concentration gradient. <br> | |||
A carrier that transports only one substrate during facilitated diffusion is called a [[Uniporter|uniporter]]. | |||
=== References: === | |||
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Latest revision as of 17:24, 4 December 2016
Passive transport is the movement of molecules across the plasma membrane down the concentration gradient without the input of energy[1], therefore the concentration determines the direction and rate of transport across the membrane.
There are two types of passive transport:
- Simple diffusion - Non-polar, water, small, hydrophobic molecules can cross the membrane by simple diffusion
- Facilitated diffusion - Many molecules (polar, charged, large, and hydrophilic) can not cross the plasma membrane, so the passage of these molecules is facilitated by membrane transport proteins (channel or carrier proteins) [2]. An advantage of facilitated diffusion is that there is potential for movement across the membrane in either direction of the concentration gradient.
A carrier that transports only one substrate during facilitated diffusion is called a uniporter.