Forces Acting Across Membranes Flashcards
Basic structure of membranes
Composed of phospholipids
Hydrophobic/lipophilic fatty acid tail
Hydrophilic/lipophobicphosphate head
Membrane proteins
Integral membrane proteins:
Receptors
Transporters (carrier and channel proteins)
Enzymes
Peripheral proteins
Receptors
Allow communication of an extracellular signal to the intracellular space to create a cellular response
Transporters
Carriers - do not create a continous pore (generally for larger molecules eg. glucose)
Channels - create a pore through the membran, usually for ions, open or gated
Enzymes
Biological catalysts
Peripheral membrane proteins
Maintain cell stucture by anchoring the membrane to the intracellular cytoskeleton
Attach cells to ECM
Perform signalling functions within proteins
Diffusion through lipid bilayer
Small
Uncharged
Hydrophobic/lipophilic
Electrical gradient
Ions creating conc. gradient are charged => also a difference in charge across membrane
Electrochemical gradient
Net effect of conc. gradient and electrical gradient
Drives direction of passive movement
Osmolarity
Total number of particles in solution (not the nature of the particles)
Tonicity
Total number of non-penetrating particles in solution (determines cell volume)
Osmolality
No. of osmoles of solute in 1kg of solvent
Endo- and exocytosis
Mechanisms for moving macromolecules across membranes without disrupting them
Isosmotic
Same total number of particles as ECF (plasma)
Hypo-osmotic
Fewer total solute particles than ECF
