Sub-topic: Active Transport
Question to ponder: What is active transport?
- A process where energy is used to move the particles of substances (through a membrane) from a region of a lower concentration to a region of a higher concentration , against a concentration gradient.
The concentration gradient slope will be shown below:
The mechanism of active transport can be shown by the sodium-potassium pump (Below). |
Instead of the normal movement of molecules/ions from higher to lower concentration, for active transport, the movement of molecules/ions is exactly the opposite.
This usually leads to the accumulation or the elimination of molecules/ions in the cell. This is different from passive transports (diffusion & osmosis). At the end of the process, these transports will reach equilibrium (movement of molecules will be equal, and they are spread equally). Does active transport needs the present of partially permeable membrane?YES! Since the particles (molecules/ions) are moving against the concentration gradient, the particles (molecules/ions) moved via carrier proteins (can be found embedded in the membrane).
Below are the two examples of active transport:1. Absorption of mineral ions in the root hairs.
*Important: This video consist of two processes - diffusion and active transport. The 1st half of the video describes the diffusion and the 2nd half of the video describes the active transport. The volume of this video might be low, please set the volume of your speaker to high or use a headset.
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2. Absorption of glucose & amino acids in the small intestine of humans.
This video describes about the function of the small intestine. Do not worry about the parts of the small intestine (e.g. duodenum etc), you will learn about this in another topic, the "Digestive system."
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What you need to know for now is about the absorption of nutrients in the small intestine and the function of villi. The actual content for this will start at 0:38 - 1:26 (must listen!)
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TcNMA <3
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