kati 7

8nm

-selective permeability-allows some substance to cross it more easily than others

lipis and proteins

phospholipids

has both a hydrophilic region and a hydrophobic region

• -various proteins embedded in or attached to a double layer (bilayer) of phospholipids.
• -lipis (phospholipids) has cholesterol lipids stuck in between
• -proteins
• -carbohydrate (outside)-establish identity foe cell
• -cholesterol helps stabilize lipid bilayer

inbetween lipid bilayer

• on one side or other,
• -often to expose parts of integral protein

• sugar units covalently bonded to lipids
• -on extracellular side of the plasma membrane use them to distinguish one cell from another

only hydrophobic and slightly charged molecules are permeable

a protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute

• transport protein for water
• -the passage of water molecles through the membrane in certain cells is greatly facilitated by channel proteins

• -no energy needed
• -diffusion of a substance across a membrane with no energy investement

• holds on to their passengers and change shape in a way that shuttles them across the membrane.
• -made for only a certain kind of substance that it will shuttle

the movement of molecules of any substance so that they spread out evenly into the available space

the region along which the density of a chemical substance decreases

diffusion of water molecules along semipermeable membrane

• the ability of a solution to cause a cell to lose or gain water.
• (remember opposited, goes to solute)
• -hypertonic-shriveled, plasmolyzed
• -isotonic-normal, flaccid
• hypotonic-lysed, turgid (normal)

polar molecules and ions imoeaded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane

uses energy to move solutes against their gradients

a single ATP powereed pump that transports a specific solute can indirectly drive the active transport of several other solutes in a solution.