Embedded Files
RELEVANT LEARNING OUTCOME:
(c) Explain how and why different substances move across membranes through simple diffusion, osmosis, facilitated diffusion, active transport, endocytosis and exocytosis.
Osmosis in the net movement of water molecules from a region of higher *water potential to a region of lower water potential through a selectively permeable membrane.
*water potential = the tendency of water to move from one place to another
👁️🗨️Watch the video to learn about how osmosis takes place, why it is important for living things, and what contributes to water potential.
Do check that you understand these terms: 'net movement', 'hypertonic', 'hypotonic', 'isotonic', 'turgor pressure'
💡Aquaporins
💡Aquaporins
While water molecules are small enough to cross the phospholipid bilayer, the rate of movement across may be too slow. As such, transmembrane channel proteins called aquaporins are found in the membrane to speed up the process.
Image credit: Vossman CC BY-SA3.0
The molecular structure of an aquaporin with water molecules passing through.
📂 Recall
📂 Recall
Based on the molecular structure of aquaporin shown above:
Which secondary structure of the polypeptide is prominent in the aquaporin?
How does having many of these structures enable the aquaporin to be positioned in the membrane?
Alpha-helices
Each alpha-helix is stabilized with H-bonds within the backbone. The polar peptide bonds are used to form H-bonds, and as such, are not able to interfere with hydrophobic interactions with the surrounding hydrophobic fatty acid tails.
In case you are interested...
Researchers have found a way to use the aquaporins for commercial use in water filtration systems, used even in space!
👁️🗨️Watch the video to find out how.
You might like to read briefly about how the technology is used for space travel.
Content
Content
Page updated
Google Sites
Report abuse