3. Membrane Structure

encloses the cell, defines its boundaries, and maintains the essential differences between the cytosol and the extracellular environment

maintains the characteristics differences between the contents of each organelle and the cytosol

provides the basic fluid structure of the membrane and serves as a relatively impermeable barrier to the passage of most water-soluble molecules.

Tail of phospholipid

protein sensors which transfer information across membrane

main phospholipids, two long-chain fatty acids

span the lipid bilayer and mediate nearly all the other functions of the membrane

most abundant membrane lipids

50% of the mass of the most animal cell membranes

Head of phospholipid

most common sphingolipid

from sphingosine (long acyl chain with an amino group (NH2) & two hydroxyl groups (OH)

It creates kink in the tail

3 types of phospholycerides

a fatty acid tail is attached to the amino group, and a phosphocholine group is attached to the terminal hydroxyl group

able to diffuse freely within the plane of a lipid bilayer

phospholipid molecules in synthetic bilayers very rarely migrate from the monolayer on one side to that on the other

Hydrophobic tails sandwitched

Tail inward characteristics

contains a rigid ring structure, to which attached a single polar hydroxyl group and a short nonpolar hydrocarbon chain

the lipids tend to rearrange spontaneously to eliminate the free edge

resemble sphingolipids; sugars

The lipid bilayer contains an unpaired electron whose spin creates a paramagnetic signal that can be detected by

amphiphilic molecules spontaneously ___ to bury their hydrophobic tails in the interior