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Cell membrane :microscope: - Coggle Diagram
Cell membrane :microscope:
Membrane basics
plasma membrane encloses the cell.
inside the cell most organelles are defined by their membrane. same function - separate specialized environments.
bilayer of lipids, with embedded proteins which define the organelle and most of the work.
a very thin layer
the film of lipid and embedded protein makes it impenetrable to most water-soluble molecules (including hormones & drugs)
makes them fluid and dynamic & fluid
most of the molecules constantly move
in the plane
of the membrane
Gonna look at the lipid bilayer in more detail.
the bilayer structure is due to the physical properties of the lipid molecules.
they assemble
spontaneously
The lipid bilayer
shapes
shpherical micelles or bilayer double layer sheets
the hydrophobic forces provides a self sealing property. - if there is a tear, the lipids of membrane will spontaneously fold to eliminate the edges
bc edges means hydrophobic parts exposed (we don't want that)
Amphiphilic
= has hydrophobic (non-polar) and hydrophilic (polar) parts.
we often see that the hydrophobic tails of lipids get
berried
while the hydrophilic parts are
exposed
.
this results in different shapes
the polar head group contains a PO4 group
the 2 hydrophobic tails are fatty acids
-once tail has 1/more cis-double bonds (
unsaturated
) and appears bent
other tail does not have double bonds =
saturated
tails between 14 - 24 carbon atoms in length
different lengths and saturation = different membrane
fluidity
list of things affecting fluidity of membrane
fatty acid composition - length & saturation
Sterol - content
temp - environment
changes in fluidity
also called
phase transition
Hydrocarbon chain is short & has double bonds (unsaturated) = fluid at low temp
different phospholipids can have different shapes: cylinders/ cones
essential for formation of membrane
seeing as they allow proteins to be embedded.
And for processes such as membrane fusion and fission (needs curvature)
