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Membrane stucture synthesis, and transport - Coggle Diagram
Membrane stucture synthesis, and transport
the framework of the membrane is the phospholipid bilayer
amphipathic (chapter 3
hydrophobic fatty acid tail (non polar)
hydrophylic phosphate head (polar)
the two leaflets are asymmetrical containing
carbohydrates
proteins (can move)
lipids (can move)
proteins bound to membranes
integral or intrinsic membrane proteins
transmembrane proteins
regions are physically embedded in the hydrophobic portion of the phospholipid bilayer
lipid- anchored proteins
an amino acid of the protein is covalently attached to a lipid
peripheral or extrinsic membrane proteins
noncovalently bound either to
integral proteins
polar head groups of phospholipids
membranes are semifluid
movement of lipids
spontaneous
lateral movement
rotational movement
via flippase
flip-flop
requires ATP
Lipid rafts
they form when certain lipids associate strongly with each other and float together
composition
unique set of membrane proteins
play a role in endocytosis and cell signaling
high concentration of cholesterol
factors affecting fluidity
length of fatty acyl tails
shorter acyl tail higher fluidity
presence of double bonds
makes the bilayer more fluid
presence of cholesterol
high temperature cholesterol makes the membrane stiff
synthesis of lipids
fatty acid building blocks
made via enzymes in
cytosol
taken into cells from food
occurs in the cytosolic leaflet of the smooth endoplasmic reticulum
fatty acids are activated by the attachment of a CoA molecule in the cytosol
activated fatty acid bond to glycerol-phosphate and are inserted into the cytosolic leaflet of the ER membrane
phosphate is removed
choline already linked to phosphate is attached
flippases transfer some of the phospholipids to the other leaflet
transfer of lipids to other membranes
lipids in ER membrane diffuse laterally to nuclear envelope
transported via vesicles to
Golgi
lysosomes
vacuoles
or plasma membrane
lipid exchange proteins
extract lipid from one membrane for insertion in another
synthesis of transmembrane proteins
directed to ER first
transferred
glycosylation
covalently attaching a carbohydrate to a protein or lipid
glycoprotein
glycolipid
play a role in cell surface recognition
N-linked glycosylation
attachment of carbohydrate to nitrogen atom of asparagine side chain
occurs in ER and membrane proteins transported to the cell surface