Unit 1 - Membrane Transport Flashcards
what is the driving force of a cell membrane?
electrochemical gradient
what two equations can be used in calculating potential of cell membrane?
- Nernst: equilibrium potential of a single ion
- Goldman: resting membrane potential of any cell
what type of core do membranes have?
hydrophobic
how is movement of water regulated?
aquaporins - selective in differents parts of the body - regulates influx/efflux
what is gating in a cell membrane?
-fluctuation between open/closed states
what is the term for agents that open/close channels?
extracellular agonists/ antagonists
what are non-selective cation channels?
allow variety of (+) ions to pass through but no (-) ions
what is the difference between ionotropic and metabotropic receptors?
activation causes flow of ions in ionotropic but n metabotropic does not cause flow of ions but causes conformational change in protein and initiates intracellular signalling
what are the three types of carrier proteins?
- uniporters
- symporters
- antiporters
what is the difference between primary and secondary active transport?
Primary: uses a source of chemical energy (e.g., ATP) to move molecules across a membrane against their gradient.
Secondary active transport: uses electrochemical gradient as an energy source to move molecules against their gradient
what are the four types of primary active transport pumps/transporters and their functions?
1) F-ATPase (coupling factor) - prime enzyme in oxidative metabolism producing ATP from electrochemical gradient of H+ ions
2) V-ATPase (vacuolar)- acidifies cytoplasmic vesicles - important for optimum pH of lyzozymes
3) P-ATPase (phosphorylation) - forms phosphorylated intermediates that drive ion translocation
4) ABC transporter (ATP-binding cassette) - variery of functions - e.g. excretion of toxic metabolites
