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Flashcards in Membrane Transport 2 Deck (14):

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
- competition