Cell mebranes Flashcards
(42 cards)
What is the cell membrane made of?
A phospholipid bilayer with proteins and carbohydrates.
What is the main function of the cell membrane?
To act as a selectively permeable barrier for transport, signalling, and energy storage.
What model describes membrane structure?
The Fluid Mosaic Model.
What holds the lipid bilayer together?
Non-covalent interactions.
What are the three main types of membrane lipids?
Glycerophospholipids, sphingolipids, and sterols.
What is the structure of a glycerophospholipid?
Glycerol backbone, two fatty acids, phosphate group, and alcohol head.
How are sphingolipids different from glycerophospholipids?
They have a sphingoid base instead of glycerol.
What is a sterol and what does it do?
A lipid with a rigid ring structure that stiffens the membrane and aids in fluidity.
What are examples of sterols in different organisms?
Cholesterol (animals), ergosterol (fungi), hopanoids (bacteria).
What factors affect membrane fluidity?
Fatty acid length, saturation, and cholesterol content.
What is a lipid raft?
An ordered microdomain enriched in saturated lipids, sphingomyelin, and cholesterol.
Why is membrane curvature important?
It facilitates vesicle formation, fission, fusion, and protein targeting.
What signalling role does phosphatidylinositol (PI) play?
It can be cleaved into second messengers like IP3 and DAG.
What is arachidonic acid and why is it important?
A lipid precursor to prostaglandins involved in inflammation and clotting.
How do hydrophobic drugs interact with membranes?
They partition into membranes and may rebind to targets or act as reservoirs.
Why are bacterial membranes good drug targets?
Because bacterial membranes differ from human ones, allowing selective toxicity.
What are common lipids in bacterial membranes?
Phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin.
What structural difference exists between Gram+ and Gram– bacteria?
Gram+ has thick peptidoglycan; Gram– has two membranes and LPS.
What is peptidoglycan made of?
β1,4-linked amino sugars crosslinked by peptides.
What are the two types of membrane proteins?
Integral (intrinsic) and peripheral (extrinsic).
What structures do transmembrane proteins use?
α-helices or β-barrels.
What are β-barrels and where are they found?
Pore-forming structures made of β-sheets, found in porins.
What are porins?
β-barrel channels in bacterial membranes that allow passive diffusion.
What are aquaporins?
Water channels important in kidneys and brain.
