Membrane Transport 2 Flashcards
What is simple diffusion and carrier mediated transport comparison
Carries facilitate the transport of substances by diffusion increasing the rate at which this process occurs over, simple, unaided diffusion
Transport rate is nonetheless much slower
What is facilitated diff and active trans
Carrier mediated transport takes two forms:
- facilitated diff - uses carrier to facilitate transfer of sub downhill from high to low conc
- activ trans - need carrier to expend energy directly or indirect to move sub uphill
What is the model of facilitated diffusion
Alternating access model
Carrier undergone spontaneous conformational changes at binding sites never at same time
Transport of solute can occur in both directions but only down corn grad
Exofacila and endo facial state
What a re the two forms of active transport
Primary and secondary
What is primary active transport
Energy directly used to move sub uphill ag conc grad
What su secondary active trans
Energy required but not directly to move sub ag conc grad
Carrier doesn’t hydrolyses atp instead over sub with second hand energy
What su the sodium a nd potasium pump
More complicated active transport - primary
In plasma mems basolateral
3 sodium out and 2 pottasium in - electogenic
What are the three important roles for sodium and pottasium ATPase
Maintains sodium a do pottasium conc grad across plasma mem of all cells
Helps reg cell vol by controlling concentration of solutes inside cell
Energy stored in electrochem gradient established by the pump can be harnessed to drive SECINDARY active transport by coupling the movement of solutes
What is secondary active transport definition
Transfer of a solute across the mem is always coupled with the transfer of the ion that supplies the driving force
What are the mechanisms which can do secondary transports
Symport - co transport - the solute and sodium move in same direction
Anti port - counter transport - solute and sodium move in opposite directions
How are glucose and galactose abs
Secondary active trans mediated by SGLT1
How is fructose abs
Facilitated diff by GLUT5
What is vesicular transport
Requires energy for vesicle formation and movement within the cell
Endocytosis - pinch off
Exocytosis - vesicle fuses with plasma mem release contents to ECF
Sec enzyme and neurotransmitters way of adding channels
What is carrier mediated transport
Substance binds to a specific carrier which undergoes conformational change allowing the transport of the substance across the mem
3 imp characteristics
- selectivity
- saturation
- competition
