Membrane Transport Pt 2 Flashcards
channels or carriers: form a pore that can be open or closed
channels
channels or carriers: can be highly selective for individual ions or they can be nonselective
channels
channels or carriers: bind specific substrates and allow them to move across the membrane only when they undergo conformation changes
carriers
channels or carriers: binding sites must become available to bind (or release) a transported molecule on one membrane side and then also on the other side
carriers
we call this form of transport is called an “alternating access model” of transport
carriers
channels or carriers: limited in how fast they can operate bc they must recognize and bind their substrates during the transport process
both!
facilitated diffusion takes place by ( )
uniporters
facilitates diffusion of a solute across a membrane
uniporters
movements of one ion type through the membrane drive (or push) the movement of another ion tyoe or a solute, often against its gradient
secondary active transport
which carrier is the simplest
uniporters
2 types of secondary active transport:
1) symporters (cotransporters)
2) antiporters (exchangers)
energy is invested, usually by ATP hydolysis, to carry out transport
active transport
channel types:
1) water channels
2) ion channels
carrier types:
1) uniporters
2) symporters
3) antiporters
4) pumps
facilitated diffusion types
GLUT1-GLUT4 Transporters
a specific solute (glucose) is bound on one side of the membrane, translocated across the membrane, and released on the other side of the membrane. The empty binding sites then rearrange to bind another substrate.
facilitated diffusion
all of the reactions are reversible and only the energy of the solute gradient across the membrane drives the reaction in one direction
facilitated diffusion
facilitated diffusion: glucose can be taken up in to hepatocytes through ( ). How is it stored?
- GLUTs
- glycogen
if glucose concentrations are high both inside and outside of cells, the transporter exhanges one glucose insode for one glucose outside
glucose glucose self-exchange; facilitated diffusion
how cotransporters transport solutes against their gradient
secondary active transport
symporters/cotransporters function similarly to uniporters excep that ( )
two substrates must bind for transport steps to take place
driving force of cotransport
energy of one substrate gradient can be used to drive the transport of the other substrate
10:1 (Na)(glucose) thing
cotransports
law of mass action
[glucose]in= [glucose]out * ([Na]out/[Na]in)^2
