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Membrane lipids and proteins - Coggle Diagram
Membrane lipids and proteins
fluid mosaic model: macros
Singer and Nicholson
lipids
phospholipid
amphipathtic
polar/hphilic head
specific functions
face outwards
non-polar/hphobic tail
varies in length
unsaturated bonds causes kinks
steroids
cholesterol + ester
amphipathic
neutral fats
like glyceride
glycolipids
proteins
integral
partially embedded
single/multi span
multimeric protein complexes: pores e.g. bacterial lactose permease
peripheral
temporarily attach to integral membrane proteins/lipids
hydropathy index
used to determine hphobic/philic of amino acid side chain
high charge density = hphobic e.g. transmembrane region as they are made of a chains
low charge density = hphilic as they are made of b sheets
evidence
structure
x-rays
are scattered and phosphate and cholesterol
neutrons
are scattered by esters
can see the trilaminar appearance (low density area surrounded by 2 dense layers) of the double membrane by
electron microscopy
freeze etching
reveals a dimpled layer and a layer with protrusions
dynamic
when you expose the membrane to a
electric field
, the proteins move laterally towards the field
when heated the membrane goes form gel to a liquid consistency
electron spin resonance
revealed that alongside lateral, they can rotate and rarely flip
frequent flip flops may be an indication cell death
FRAP/fluorescence recovery after photobleaching
cell + fluorescent antibody
partially bleached by fluorescence
over time patch disappears by diffusion
cell fusion technique
fuse human + mouse cell
human + red antibody
mouse + green antibody
over time the colour mix
some proteins within the membrane are immobile as they are attached to the cytoskeleton