Question

20) A diseased cell has an intracellular calcium concentration of 1 mM. The extracellular solution has a normal amount of calcium. The mitochondria has its normal level of internal calcium. If many calcium channels were opened in a mitochondria were opened up, what would the voltage of the interior of the mitochondria likely be compared to the cytoplasm of the cell?

a) -90mV

b) -60mV

c) -30mV

d) 0mV

e) +30mV

22) A nerve cell with normal levels of intracellular calcium is treated with intracellular IP3, which opens calcium channels in the endoplasmic reticulum. What would the transmembrane voltage across the plasma membrane of the cell (that is, the voltage of the cytoplasm relative to the extracellular solution bathing the cell) if this occurs and calcium has no other effects on the cell?

a) -90 mV

b) -60 mV

c) -30 mV

d) 0mV

e) +30mV

30) A molecular biologist replaces all normal leak channels with a type of leak channel that is permeable to calcium. What would the resting voltage of this cell likely be?

a) -90mV

b) -60 mV

c) 0 mV

d) +60 mV

e) +90 mv

40) A molecular biologist eliminates all normal leak channels and blocks all other voltage-gated conductances in a cell. She then puts in two new channels, which are both normally open and not affected by voltage. One is permeable only to potassium and the other is open only to sodium. If there is 10 mM Na inside and 100 mM Na outside and 10 mM K outside and 100 mM K inside, what will the resting membrane voltage of the cell be?

a) 0mV

b) -60mV

c) +60mV

d) -120 mV

e) +120 mV

Answer 1