00:01
This multi -part question is asking us about several different aspects of the phospholipid bilayer.
00:08
So first off, it's describing the structure of the bi -layer, which is composed of fossilipid molecules in a bi -layer orientation.
00:24
So i'm drawing it with the polar heads of the fossil lipid bilayer.
00:32
Facing both outward and inward and then the hydrophobic tails of the membrane all clustered together inside the interior of membrane.
00:45
So around the exterior of the cell is a mostly aquaous environments, a lot of water molecules, and similarly the interior of the cell is also filled with a lot of water molecules h2o and interior.
01:14
And when we think about this phospholipid bilayer, the most interesting thing to note is that while these head groups are all polar and similar, and therefore can easily interact with the water in the interior and exterior environments, there's a strip here that's hydrophobic, or non -phobic.
01:42
So that has really interesting repercussion in that getting on to the second part of part a, that polar molecules will be relatively capable of diffusing in and out of the cell, but non -polar molecules will not.
02:05
So for example, water cannot diffuse across the membrane, but instead needs to go through a change.
02:15
In the membrane called them aquaporin to travel in and out.
02:19
So in that sense, the cell can control water coming in and out of the cell by controlling the number of aquaporins of tests.
02:30
By contrast, oxygen, o2 is a relatively non -polar molecule, and this is therefore able to diffuse into and out of the cell without the help of the transport.
02:47
So the cell can exchange oxygen passively without any transporter molecules but other molecules such as water it can acquire passively or actively but require a transporter and maybe most importantly a lot of some other small molecules like maybe chloride ions or potassium ions are unable to permeate the cell barrier.
03:28
So the phospholid bilayer, by having this hydrophobic strip that's impermeable to polar ions, ions impermeable.
03:47
The cell can really control its concentration of salts and and ph by controlling the abundance of hydrogen ions and etc.
04:06
So moving on to the second part of the question i've basically drawn a graph for b here showing the change in oxygen diffusion as a function of temperature for various different materials...