Membrane transport Flashcards
Types of gating
- Ligand-gated
- Voltage-gated
- Mechanically-gated
TRUE OR FALSE
Passive transporters can be symport
FALSE
They are only function as uniport through an ‘alternative access mechanism’.
Properties
Passive transporters
- Highly selective
- Slow
- Saturable (reaches Vmax)
- Molecule must BIND to the binding site.
What is the mechanism that passive transporters use?
Alternating access mechanism
TRUE OR FALSE
Primary active transporters are channels
FALSE
They are pumps!
P-type transporter mechanism
- ATP hydrolysis.
- Results in ADP + Pi
- The protein pump is phosphorylated causing a conformational change
P-type transporter examples
- NA+ , k+ -ATPase (antiport)
- Ca2+ - ATPase (uniport) [->out of the cell]
- H+ ,K+ -ATPase (antiport)
What do P-type transporters transport?
Cations
(e.g. H+, K+, Na+, Ca+)
Where are V-type transporters
Found in vesicles (ergo are intracellular)
V-type transporters
- Primary active transporter
- found in vesicles
- Pump H+ into organelles
- Function via ATP hydrolysis
F-type transport
- Primary AT
- found in inner mitochondrial membrane
- Pump H+
- Funcion via ATP synthesis
F-type transporter mechanism
The movement of H+ down its gradient causes the ATP synthesis.
Creates energy
ABC transporters
- Primary active transporter
- All ABC transporters are dimers
- Requires two ATP molecules
Dimer
A molecular complex consisting of TWO proteins.
In molecular transport, dimers are PROTEIN PUMPS that consist of two proteins not one.
ABC transporter mechanism
- Two molecules of ATP bind to the dimer causing conformational change.
2 . Molecule diffuses into the otherside.
3 . ATP are hydrolysed, the pump goes back into its original conformation.
However, the pump is NOT PHOSPHORYLATED! at any point.
