Active membrane transport Flashcards
(24 cards)
Active transport
movement of molecules from high to low concentration and requires energy
which ion has the lowest concentration in the extracellular space?
K
NA having high concentration outside the cell, what happens?
cell needs constant energy to complete its procedures therefore NA moves from outside to inside (high to low concentration)
K has a high concentration inside the cell, what happens?
K moves from inside to outside (along the concentration gradient)
what does active transport require
similar to facilitated diffusion, it requires carriers that combines specifically and reversibly with transported substances
what are the two types of active transport
primary active and secondary active
primary active transport uses _____ as a source of energy.
ATP, by burning glucose then used to carry body function
hydrolysis of ATP results in
Phosphorylation of the transport protein
example of primary active transport
NA/K pump - also called NA-K ATPase
channel binding to ATP before hydrolysis of phospho-regulation stimulates the channel to change its ____
shape
mechanism of NA-K ATPase:
1- The pump is in “open inside, high NA-low K affinity”. three NA ions bind and trigger the ATPase activity
2- bound ATP is hydrolyzed to ADP and P
3- Released chemical energy causes the transition of the pump molecule to the “open outside, low NA- high K affinity”
4- 2 K ions bind to the pump
5- release of dephosphorylation is triggered (p)
6- dephosphorelated pump binds to another ATP molecule, decreasing the pumps affinity to K -> relase to K into the cytoplasm
repetition of this cycle creates gradients of NA and K concentrations across the membrane
NA gradient created by primary active transport can serve as a source of energy for
secondary active transport
symport system
two substances are moved across the membrane in the same direction
antiport system
two substances are moved across the membrane in opposite directions
primary active mechanism produces
mechanisms
secondary active transport
against gradient that was created by primary active transport
example of symport system
amino acid transport
example of antiport system
sodium-hydrogen exchange
vesicular transport meaning and types
primary active transport which is driven by energy source ATP or GTP. large particles or macromolecules are transported by it.
types are exocytosis and endocytosis
exocytosis meaning proccess and examples
- mechanism that moves substances out the cell
- substance to be released is first enclosed in a vesicle which then migrates to the plasma membrane, fuses with it, ruptures and spills contents
- hormone secretion, neurotransmitter release, mucous secretion and ejection of some waste products
endocytosis meaning, proccess and types
- for large macromolecules or particles to enter cells.
- substance to be taken is progressively enclosed by an infolding potion of the plasma membrane, after the membranous vesicle is formed, it pinches off from the plasma membrane and moves into the cytoplasm where the contents are digested
- phagocytosis, bulk-phase endocytosis, receptor mediated endocytosis
phagocytosis
large external particle is surrounding and becomes enclosed in a plasma membrane sac
bulk phase endocytosis
plasma membrane sinks beneath an external fluid droplet containing small solutes; membrane edges fuse forming a fluid-filled vesicle
receptor-mediated endocytosis
selective process; external substance binds to membrane receptors and coated pits are formed
