Bio Chapter 7

• Allo some substance to cross plasma membrane more easily
• Polar substance like glucose and water pass slower than nonpolar  like oxygen ,co2 and hydrogencarbon

• have both hydrophililic region and a hydrophobic region.
• Ex: phopholipid and other membranes

Model of plasma membrane

Phospholipid bilayer heads, hydrophobic tail inside, Hyrophoci region between the heads

membrane prteins  that penetratr the hydrophobic interior of lipid bilaye

• no embedded in the lipid bilayer
• loosely bound to the surface of the membrane
• exposed to part of intergral proteins

• Transport
• Enzymatic activity
• Signal transduction
• cell cell recognition
• intercellular joining
• attachment to the cytoskeleton and ECM

channel protein, hydrophilic channel that certain molecukes use it as tunnel through the membrane

• the movement of molecules of any substance so that they spread out evenly into avaliable space
• concentration gradient - substance diffuse down
• no work is needed
• passive transport - no energy
• active transport - yses energy

the diffusion of free water across a selectively permeable membrane

• the ability of a surrounding solution to cause a cell to gain or lose water
• isotonic - same , no net movement of the water
• hypertonic - cell lose water, shrivel, and probably die
• hypotonic into cell - water enter cell fast make it swell and lyse(burst)

plant cell place in a hypertonic environment -> CELL SHRIVELS and lose water to surrounding -> die

voltage across a membrane

single ATP powered pump that transports a specific solutes in a mechanism called  a cotransport.

cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane

the cell takes in biological molecules and particulate matter by forming new vesicles from the plasm membrane