ch6.lipids and bilayers

• Hydrophilic heads: face water
• Hydrophobic tails: stay away from water

together form a phophlipid bilayer

• -small nonpolar melecules pass through (permeability)
• -large polar (hydrophilic) molecules cannot.

• -single bonds like C-C are tightly packed
• -carrying max possible hydrogen
• -fatty acid tails

• -if its a double bond C=C
• -theres a kink
• -loosely packed

• -movement along concentration gradient
• -from high concentration to low

• -diffusion of water across lipid bilayer
• -high concentration to low
• -For osmosis of water to happen, two solutions have to beseparated by a selectively permeable membrane, that allows water to go through, but not thesolutes dissolved in it.

water moving outside the cell

the cell is submerged in a solution that has less concentration of solutes, water will move into the cell by osmosis

If solute concentrations of the cell and the outside solution are the same,water will move in and out at the same rate.

Hydrophilic side to face the water outside the membrane, hydrophobic side to face the interior of the membrane.

Proteins in the membrane may be inserted into the membrane

just attached loosely on the surface

• -ion channels are pores
• -move from high to low
• -passive transport (no energy)
• -gated channels (can open or close)

• -passive transport
• -connect to molecule to push through
• -ex. glucose

• -active transport
• -energy comes from ATP
• -sometimes pumps only move one type of molecule or ion