Biology - Ch.7 & 8

Front 1

selective permeability

Back 1

allows some substances to pass more easily than others -
b/c of hydrophobic core

Front 2

amphipathic

Back 2

has both hydrophillic and hydrophobic regions

Front 3

currently accepted membrane model

Back 3

fluid mosaic model
-phospholipid bilayer
-embedded proteins, which are also amphipathic
-fluid - able to move

Front 4

membranes are held together by...

Back 4

hydrophobic interactions in the core, allows phospholipids to move laterally quite rapidly, but rarely do they flip-flop; larger membrane proteins may drift but slowly

Front 5

membrane fluidity

Back 5

-influenced by temp.
-as temp. decreases the membrane becomes less fluid and can eventually solidify(not good)
-presence of unsaturated fatty acid chains in membrane phospholipids make membranes more fluid
-cholesterol resticts fluidity at warmer temperatures but prevent solidification at warmer temperatures

Front 6

peripheral proteins

Back 6

-not embedded
-loosely bounded to the surface

Front 7

integral proteins

Back 7

-penetrate the hydrophobic core, span the entire membrane
-they also have a hydrophobic core; usually made of alpha helices
-where they are in contact with the aqueous environment, they are hydrophillic

Front 8

membrane sidedness

Back 8

-membranes have distinct inside and outside faces
-layers may differe in lipid composition and proteins have specific directions
-outer surface has carbohydrates
-means the ER must synthesize the membrane from the inside out

Front 9

functions of membrane proteins

Back 9

-transport
-enzymatic activity
-signal transduction
-intracellular jioning
-cell to cell recognition
-attachment to cytoskeleton/extracellular matrix

Front 10

glycolipid

Back 10

-sugar and lipid

Front 11

glycoprotein

Back 11

-sugar attached to membrane protein

Front 12

oligosaccharide

Back 12

membrane carbohydrates usually branched these --simple sugars

Front 13

permeability

Back 13

-depends on molecules interaction with the hydrophobic core
-non-polar/hydrophobic molecules pass easily
-polar/hydrophillic/ions have more difficulty passing

Front 14

transport proteins

Back 14

-these proteins carry out facilitated diffusion
-allow specific ions/polar molecules to cross the membrane through itself
-every transport protien is specific to one kind of substance

Front 15

diffusion

Back 15

tendency of molecules to spread out in the available space

Front 16

passive transport

Back 16

-diffusion of a substance across a biological membrane
-w/concentration gradient
-no energy need, includes transport proteins

Front 17

Osmosis

Back 17

passive transport of waterin selectively permeable membranes

Front 18

tonicty

Back 18

hypertonic-more solute concentration
isotonic - equal solute concentration
hypotonic - lower solute concentration

Front 19

reactions to tonicity

Back 19

hypertonic - cells will lose too much water and shrivel and die, plasmolysis in plants
isotonic- no net gain of water(plants are flaccid)
hypotonic - cell will take on too much water and animal cells lyse (burst) but plant cell walls exert a pressure back on the water and the cell becomes turgid(good!)

Front 20

aquaporins

Back 20

facilitate massive amounts of diffusion of water

Front 21

gated channels

Back 21

-open or close dependingon the presense or absence of a physical or chemical stimulus

Front 22

active transport

Back 22

-cell must spend energy to transport substances against their gradient

Front 23

Energy supplied by...

Back 23

phosphorylation of ATP

Front 24

exocytosis

Back 24

transport vesicle from golgi fuses with the membrane and spills contents

Front 25

endocytosis

Back 25

brings in large molecules which couldn't otherwise cross the membrane

Front 26

phagocytosis

Back 26

-"cellular eating"
-large "food" particles engulfed by pseudopodia

Front 27

pinocystosis

Back 27

-"cellular drinking"
-vesicle around droplet of extracellular fluid
-non-specific
-used to get ions in the surrounding ECF

Front 28

receptor-mediated endocytosis

Back 28

-ligands bind to protein receptors which trigger the formation of a vesicle
-allows cells to acquire bulk quantities of specific materials