Phospholipid layer

The cell membrane (also called the plasma membrane, plasmalemma or "phospholipid bilayer") is a semipermeable lipid bilayer found in all cells.[1] It contains a wide variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes, and also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall"
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[nalgaface123456789]

what i dont understand is when a phospholipid bilayer is penetrated by a water molecule in the outside of the cell and how it enters the cytosol

if the tails are hyrdrophobic why dont they act adversely when a water molecule penetrates the first layer and is inside where the hydrophobic tails are?

wont the second layer turn upside down?

[felipelicon]

Water enters the cell by channels called Aquaporins.

Tetramers with four identical subunits

Six membrane domains in each subunit

Each with a water pore

Predominantly expressed in cells that express high permeability to water (erythrocytes, kidney)

[nalgaface123456789]

thanks for clarifying that but my question is stil unanswered

[felipelicon]

The second layer wont turn upside down. The Cell membrane wont shift its shape.

[felipelicon]

The top layer is the Choline group, which is bounded to a phosphate.

CH2-CH2-N(CH3)3

The yellow part is the methyl radical CH3

[mazzc7]

as I look at it slowly...i cant see the bilayer the hydrophobic and philic parts of the fatty acid arent clear enough and I get dizzy looking at it....it zooms in and out. Hope you teacher appreciated your hard work....but it isnt useful for students trying to understand phospholipid bilayers.

[felipelicon]

That's true, is not very useful as a study aid, I apologize. This video is complementary to another animation. I appreciate the feedback, thank you for all your comments.

[MyStIcTrE3]

@MyStIcTrE3

Imagine a layer of metal-sponge-metal. If you pour water on the surface it will not penetrate. Right? Now drill a few dozen holes and press fit pvc tubes fitting those holes. Now pour water. It will partially drip trough the holes onto whatever is underneath. But, the sponge between the metal layers will always stay dry

[MyStIcTrE3]

@nalgaface123456789

I know your question is a year's old. If it is still not answered,remember the membrame is selectively permeable - Aquaporins (transmembrane protein channels embeded within the membrane) connect the cytoplasm to the extracellular fluid so water can flow ( by Osmosis of course) . It doesn't matter if the tails are hydrophobic, it has nothing to do with it. The polar layers are always hydrated, to keep you alive!

[AbsoluteJake]

@nalgaface123456789 Lipid bilayers in biological conditions are much less ordered as shown here. Each lipid in reality is dancing like a crazy person with is acyl chains creating gaps between the lipids. This allows water to sneak through the gaps one at a time, which is a slow process if you want to transport large quantities of water. Once water is in one of the gaps, basically the dancing lipids kick it out towards the head groups, which could go through the layer or back where it came from.

[Johnathon394]

20,714 people want a good grade in bio

[nalgaface123456789]

oh ok

thanks for cleaaring that up

its because im taking ap bio and its pretty complicated for me