Intro To Cell Membranes Flashcards
(46 cards)
What does the appearance of biological membranes differ on?
They differ depending on location and function
What do plasma membranes do ?
They provide cell boundary and prevents movement of materials in to and out of the cells
What do organelle membranes do ?
Divide cytoplasm into compartments
What are the fundamental properties of membranes?
- Barrier
- Flexible, self-repairing, continuous
- Selectively permeable
Can phospholipids move about in the bilayer?
Phospholipids can rotate or exchange in the lateral plane of the membrane - but normally move very slowly from one leaflet to the other
What determines the fluidity of the lipid bilayer?
Its composition. The greater the number of double bonds, the shorter the acyl chains, the less tightly packed the molecules are = greater the fluidity
What does amphipathic mean?
It is a molecule which has a polar and non polar region.
What determines the fluidity of lipid bilayer?
No. of double bonds and No. of C atoms in the fatty acid chains of the phospholipids.
How are phospholipids Amphipathic?
Polar Headgroup and hydrophobic tail.
What state of matter are membranes at the temperature of the organism?
Fluids (liquid)
Describe the composition of a cell membrane in a cold - blooded animal.
More double bonds and/or shorter acyl chains than membranes of warm blooded animals
What is the net charge of Phosphatidyl serine?
-1
What effects does cholesterol have on the cell membrane?
Makes the membrane less permeable.
Packs between phospholipids and makes the membrane less deformable at the surface. It does not make the overall membrane more rigid
What does high concentrations of cholesterol do to the membrane ?
Prevents the membrane from becoming crystalline
What is crystalline?
Solidification of membranes.
What are formed by lipids in aqueous solutions?
Micelles or bilayers.
What do lipid bilayers preferably form?
Sealed compartments.
What are integral membrane proteins?
They are proteins that directly insert in the membrane by a hydrophobic domain.
What are peripheral membrane proteins?
Peripheral membrane proteins are extrinsic membrane proteins temporarily bound with membranes which helps in cell signalling.
What two ways can peripheral membrane proteins associate with the membrane?
- Associate with integral membrane proteins or directly bind lipids
- Covalently bound lipids which insert into the membrane
What are micro domains?
micro domains refer to small, specialized regions within the cell membrane.
What do membrane lipids form?
Clusters or microdomain
What forms rafts?
Cholesterol and sphingolipids can form micro domains called rafts.
Membrane (raft) is slightly thicker in the microdomain
Where do tight junctions prevent movement?
They prevent movement between apical and baseolateral membranes
