What is a lipid?
A water insoluble(hydrophobic) molecule that is composed of a carbon and hydrocarbon atoms(hydrocarbons).
What are examples of lipids?
Triglycerides, tryglyglycerols(energy storage), and phospholipids,sterols(membranes)
Fatty acids:
Long chain of C atoms with a carboxyl group at one end. Vary in the # of carbons in the hydrogen chain, and the presence/ amount of carbon-carbon double bonds.
Saturated fatty acids:
No double carbon-carbon bonds.
Unsaturated fatty acids:
1+ double carbon-carbon bonds(creates bend).
Triaglglycerols:
Energy storage molecule that has 2 fatty acid tails bound to a glycerol anchor.
Phospholipids:
Amphipathic molecule(water loving head and water hating tail).
That spontaneously forms bilayers in water.
Biological memebranes:
Compaartmentalize the cell. The plasma membrane seperates the out from in, and internal membranes create additional cellular regions.
membranes are ___________ barriers and have ____________ for communication and and chemical reactions.
Selectively permeable
scaffolds
What is the fluid mosiac model?
Both lipids and protiens coexist in the membrane and molecules can move laterally in the membrane.
Fluid lipid bilayer:
Most phospholipid molecules are independent, not attached to one an other, and free to move along the plane.
What are some different parts of the fluid mosiac model?
Carbohydrate groups: On the outside of the plasma membrane.
Glycoprotien: Carbohydrate+ protien.
Glycilipid: carbohydrate+lipid.
Intergral protiens: Cross the entire hydrophobic region of the membrane.
Peripheral protiens: do not cross the membrane but aid in process(mantian structure and speed up reactions).
What are the 4 factors that increase membrane fluidity?
1) Increase temp
2) Presence of sterols(cholesteral)
3) Presence of unsaturated fatty acids
4) Smaller chain length in the hydrocarbon tail.
How do sterols regulate membrane fluidity?
animal cells insert cholesterol into the bilayer to prevent excess viscosity(stops phospolipids from packing to tightly) and prevents excess fluidity by filling gaps between phospholipids.
Fluid membranes are ____ _____ and _______ ________ pass through the bilayer. .
More leaky
More solutes
Membrane ________ effects permeability.
Fluidity
________ membranes are better barriers and let ________ solutes pass through the membrane at a _________ rate.
Viscous
Less
Slower
Selective permeability:
1) Small non-polar can pass through
2) Small uncharged polar pass through slowly.
3. Large uncharged polar molecules and ions can’t.
What conditions are required for water to cross the membrane?
Hydrophilic interior, hrydophobic exterior, and a channel(aquoporins).
Diffusion:
Dissolved molecules move to evenly distribute, from high to low concentraions, until equilibruim is reached.
What are the two conditions achieved at equilibruim?
- The concentration gradient is eliminated.
-There is a lower energy state.
Diffusion only works if the __________ is able to move through the __________. If it is not a solution with reach equilibrium through ____________.
Solute
Bilayer
Osmosis
What is osmosis:
Diffusion of water, water moves from low to high concentration of solute, until solute reaches equilibruim.
Tonicity:
Relative solute concentration, difference across the lipid bilayer. Affects diffusion and osmosis across the membrane.
