Week 4 (cell membranes) Flashcards
fluid mosaic model
-membranes are not rigid
-proteins are embedded and float freely
-selectively permeable
which way do lipid molecules move in a membrane
laterally <->
why are cell membranes said to be fluid
lipid bilayers are not bonded to one another allowing movement like a fluid
sterols
maintain constant fluidity of the membrane
are membranes symmetrical?
no
each half is different
3 types of membrane proteins
Integral- go right thru membrane
Peripheral- either side
Amphitropic - right thru
integral membrane proteins interact with what?
hydrophobic core
peripheral membrane proteins interact with what?
hydrophilic surface
what molecules are able to pass thru the phospholipid bilayer?
-non polar molecules (O2,CO2)
-small uncharged polar molecules (hydrophobic)
what molecules are not able to pass thru the phospholipid bilayer?
-large uncharged polar molecules (sugars) (hydrophilic)
-Ions (have a charge)
facilitated diffusion
-facilitated by membrane proteins
-follows concentration gradient
carrier proteins
-bind specific solutes and transfer them across the lipid bilayer
isotonic
-equal solutes in the cell and outside
hypertonic
more solutes outside the cell (water rushes out )
hypotonic
more solute inside the cell (water rushes in )
active transport
-pumps solutes against their concentration gradient NEED ATP
primary active transport
moves one molecule with direct use of ATP
secondary active transport
moves two different molecules with indirect use of ATP (uses concentration gradient as well)
symport
the two molecules are moving the same direction
antiport
two molecules are moving in opposite directions
