3B Passive Transport Flashcards
Why is it important for the plasma membrane to be selectively permable?
Cytosol can preserve a specialised internal environment separate from the extracellular fluid
What is passive transport?
The movement of molecules through a semi-permeable membrane and down the concentration gradient, without the input of energy
What is simple diffusion?
The passive movement of molecules from areas of high concentration to areas of low concentration occurs due to the kinetic energy stores in a molecule, which causes them to randomly move around and bounce off each other
What types of molecules can pass through with diffusion?
- non-polar, uncharged, or hydrophobic, small molecules
eg. oxygen and carbon dioxide
What is facilitated diffusion?
A type of passive transport where molecules move through a phospholipid bilayer with the aid of a membrane protein (protein channel or carrier protein)
What is a protein channel?
A transmembrane protein pore in a phospholipid bilayer that selectively enables the transport of large or polar molecules
What is a carrier protein?
A membrane protein that undergoes conformation change to transport molecules across a membrane
What is osmosis?
The passive transport of water through the cell membrane from a region of law solute to a region of high solute (so less solution)
What is tonicity?
A measure of the relative concentration of solutes on either side of the cell membrane
What is hypertonic mean?
There is a higher solute concentration
What is adenosine triphosphate (ATP)?
A high energy molecule that when broken down, provides energy for cellular processes
What molecules can osmosis?
water molecules
What molecules are transported through facilitated diffusion?
polar/hydrophilic, large molecules
eg. carbohydrates, amino acids
