Membranes

• Lipid Bilayer
• transmembrane proteins
• Network of supporting fibers
• Exterior Proteins and Glycoproteins

Proteins embedded in phospholipid by layer

membrain is fluid-mosaic

proteins/phospholipids move freely in membrane

diversity of proteins to exist in the membraine

switch from fluid state to solid state

temp depends on lipids

Unsaturated fatty acids are more fluid than saturated fatty acids

must be fluid to work properly (looks like salad oil)

Some substances pass easily/blocked completely

some allowed in/out only through specfic transport protens

• Passive Transport
• Active Transport
• Bulk Transport

Moves substances down concentration gradient

• Diffuson
• Facilitated diffusion
• osmosis

Molecules constantly in motion/spread out

like distance between each other

diffuse from higher>lower concentration until equally spread out

Hydrocarbon,oxygen,carbon dioxide, some hydrophobic membrane

involves proteins embedded in plasma membrane

depend on 2 proteins to shuttle substances:

• channel proteins
• carrier proteins

membrane proteins form channels line with polar amino acids

non polar (hydrophobic amino acids face outside channel toward fatty acid tails of lipid molecules

Gates can be open/closed-many mechanism for controlling this

polar aa's lining interior of channel only attract one specific type of ion

channels ions interact with the protein

allow diffusion in both directions-one way sugars/amino acid transported

movement depends on concentration of gradient

how solvents/water crosses

higher concentration of solute

animall-shrivel and die

lower concentration of solute

-animal cells swell and burst

equal concentrtion of solute on either side of membranes

reason why plants stand up

pressure the cytoplam exers on the cell membrane creating a turgid cell

-plants happy with pressure/not enough water becomes floppy

makes cells firm

maintaining water balance important in animal cells

• requires energy powered by ATP
• move agains concenration gradient

high to high referred transferring up gradient

low to low referred to establishing down gradient

3

move single type of solution 1 direction

single membreane protein moving 2types of solution at a time

• symport
• antiport

move 2 solutes in the same direction

move 2 solutes in opposite directions one into cell and other in outer cell

sodium potassium pump> moves sodium out and potassium into it

cells use to secrete large substances outside cel

cells use to make material into cell

cell takes in liquid

cell takes in particles

• specific
• trigger by bingding molecules to their receptors