Transport = plasma membrane Flashcards
What are the types of transport across the plasma membrane?
simple diffusion
facilitated diffusion
osmosis
active transport
What is simple diffusion? What are the features of it?
no energy is required
- driven by chemical potential
moves from high concentration to low concentration towards equilibrium
What is facilitated diffusion? What are the features of it?
passive transport aided by proteins
- speeds up the passive movement
membrane becomes semi-permeable with proteins
protein carriers
- gated - closed until it receives a chemical or electrical signal
- non-gated = always open
protein channels
there can be more than one transporter for the same molecule
- glucose can have GLUT 1, 2, 3, 4 and 5 transporters
What is osmosis? What are the features of it? What are the types of solution?
process by which water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration to balance the solute concentrations
Hypotonic solution : solute concentration outside cell < inside the cell = cell gains water
Isotonic solution : solute concentration outside cell = inside cell = no net water movement
Hypertonic solution : solute concentration outside cell > inside cell = cell loses water
What is active transport? What are the features of it?
requires energy input
moves substances from a low to high concentration against a concentration gradient
allows cells to maintain concentration gradients that differ from their surroundings
What causes cystic fibrosis?
caused by a mutation in chloride channel that controls efflux of chloride ions and water into the lung cavity
- loss of function of the chloride channel results in reduced efflux of water by osmosis into the lung cavity
- results in a failure to hydrate the mucus secreted into the lung cavities which becomes thick and cannot be moved out of the lungs easily
- accumulating of mucus causes breathing difficulties and increased risk of infections
can be fixed with ion channels
