Section 6.2 Phospholipid Bilayers

2 sheets of phospholipids align with heads and tails facing

heads: out and tails: in

Form spontaneously

Form spontaneously: No outside

Vesicles form in the lab

phospholipids and liposomes

liposomes

Artificial membrane-bound vesicles

Small bubble-like structures surrounded by

phospholipids

Vesicles are important for

vaccine delivery

vesicles are in what form

liquid

Liposomes are not formed in

cells

lipid bilayers have what permeability

selective

what crosses through the lipid bilayer easily

Gases

what passes through relatively easy

small uncharged polar molecules (H2O, glyercol)

what moves through the lipid bilayer but it is hard

large, uncharged polar molecules

What can not pass through lipid bilayer

small ions

can move but its hard: that’s why there are ? channels to make it easier

Glucose

to measure permeability of lipid bilayers

Tendency of given substances to pass through and substance on one side and measure it on the other side

what is more MORE  PERMEABLE

Unsaturated Hydrocarbon Chains, Shorter Tails, No Cholesterol, and High Temperatures

Less permeable

Saturated Hydrocarbon Chains, longer tails, with cholesterol, low temperatures

Lipid bilayer with short and unsaturated hydrocarbon tails =

higher permeability and fluidity

Lipid bilayer with long and saturated hydrocarbon tails =

lower permeability and fluidity

Hydrophobic interactions become stronger as saturated hydrocarbon tails

increase in length

Adding cholesterol to membranes

increases the density of the hydrophobic section

increases the density of the hydrophobic section =

decreases membrane permeability

Very hydrophobic or hydrophilic ; takes up space or less space and adds or removers to the density

hydrophobic ; takes up space; adds to the density

Glycerol is polar or nonpolar

polar