Membrane Transporters

Question 1

Primary vs Secondary Active Transport

Answer 1

Primary transport directly uses ATP hydrolysis to move ion against concentration gradient
Secondary uses a non-ATP energy source, such as another ion’s concentration gradient, to move an ion against its concentration gradient

Question 2

Cotransport

Answer 2

Secondary active transport where all ions move in same direction across the PM

Question 3

Exchange Transport

Answer 3

Secondary active transport where ions move in opposite directions across the PM

Question 4

Conceptual H/K exchanger

Answer 4

Infusing extra K causes acidema, infusing extra H causes hyperkalemia
This occurs via multiple pumps in parallel
Ex Hyperkalemia activates Na/K pump, but cell is slowly depolarized form increased K so bicarbonate/Na pump does not work and bicarbonate is not pumped into blood to reduce [H]
Would be nice to have K/H pump since they need to be on opposite side of membrane

Question 5

Glucose transport

Answer 5

Glucose passively enters cell down concentration gradient via glucose transporter, gets phosphorylated to glucose-6-phosphate which cannot utilize transporter to leave

Question 6

Hyperkalemia Treatments

Answer 6

CBIGK: calcium, bicarbonate, insulin&glucose, Kayexalate

Adding bicarbonate alkylzes blood causing K uptake
insulin and glucose gives energy to Na/K pump
Kayexalate is ion exchanger that initially binds Na but has higher affinity for K and is excreted.