-does not require energy -transport driven by diffusion -e.g. blood cell typically have higher [glucose] outside than inside so there is no need to waste energy bringing it in
transport that requires energy and moves at least one molecule against the gradient
-provide channels for movement of material thorough them -only allow very specific molecules to enter
- requires ATP energy - uses phosphoaspartate intermediate - moves calcium in, ATP bind and gets transferred to aspartic acid. ADP Leaves, protein changes shape and allows Ca+ through. Rest of process invovles the removal of the phosphaste from the aspartic acid (hydrolysis). once reomoved can do again. driven by hydrolysis of ATP
- cells create a [difference] that is is used to keep the osmotic balance while also providing a way for cells to move thing in
-uses [difference] and electrical potential across membrane to move glucose with Na -is performing active transport w/o directly using ATP. glucose is moving against gradient - is a symporter
- poison used in tiny amounts for heart patience -knocks out the Na/K pump and messes with the Na/Ca Pump - by blocking the pumping of Na it lowers Na gradient so less Na comes in thus less Ca out - used to treat conjestive heart failure (heart is not pumping hard enough) as Ca causes muscle contraction.
Sym- vs. Antiporter
-Antiporter moves molicules in opposite directiions -Symporter moves molecules in the same direction
- used by bacteria to move lactose into cells -uses proton gradient to move molecules across membrane - once a proton binds to the carboxyl the charge changes and thus the shape of the protein and lactose is then able to bind. Once bound the protein changes shape again and allows the lactose in. H+ wanted to come in and comes off carboxyl readily in the cell.
Na/ Ca Pump
-Found in muscle and heart tissue uses Na gradient to drive Ca out of a cell -is an antiport -Na gradient is dependent upon Na/K ATPase
Always have an intermediate w/ covalent bond between phosphate and asaprtic acid
-have common set of domains labeled ABC -e.g. multidrug-resistance protein (MDR) found in a variety of cells and drugs administered will become less effective (kicks drug out)
-Relies on Na & K gradients -normal sit: low [Na] in, high [Na] out, high [K] in, low [K] out. -Burn Finger begins stimulus for nerve signal (pain). 1)As signal starts Na gates open and Na comes rushing in and depolarization occurs (a voltage change) 2) open K gates to balance charge - repoarization - but it overshoots 3) restoration of chare balance (recovery) - signal starts @ one end and moves to the other
-found in part of the puffer fish. is fatal. - is a Na channel inhibitor. prevents movement of sodium into cells
at a nerve junction there are synaptic vesicles. as a signal comes down vesicles fuse to membrane and release neurotransmitters into the synaptic cleft and cause gates to open in next cell
Na/ K Channels
-K > Na thus K channel must be physically bigger. -K must be desolvated (shedding of water) in order to be the correct dimensions to pass through the channel and also be energetically favorable - K movement through the channel is optimized by close range interactions inside the channel
Want to see the other 16 Flashcards in Membrane Transport?JOIN TODAY FOR FREE!