20) A diseased cell has an intracellular calcium concentrationof 1 mM. The extracellular solution has a normal amount of calcium.The mitochondria has its normal level of internal calcium. If manycalcium channels were opened in a mitochondria were opened up, whatwould the voltage of the interior of the mitochondria likely becompared 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 istreated with intracellular IP3, which opens calcium channels in theendoplasmic reticulum. What would the transmembrane voltage acrossthe plasma membrane of the cell (that is, the voltage of thecytoplasm 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 witha type of leak channel that is permeable to calcium. What would theresting 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 channelsand blocks all other voltage-gated conductances in a cell. She thenputs in two new channels, which are both normally open and notaffected by voltage. One is permeable only to potassium and theother is open only to sodium. If there is 10 mM Na inside and 100mM Na outside and 10 mM K outside and 100 mM K inside, what willthe resting membrane voltage of the cell be?

a) 0mV

b) -60mV

c) +60mV

d) -120 mV

e) +120 mV