Section A QUESTION 1 - Answer ALL PARTS of this question. [100 marks total] Experiments were designed to investigate how a potential therapeutic compound, Compound A123, affects the plateau and repolarisation phases of the ventricular action potential. In initial experiments, Channel D, which is known to play a significant role in the plateau and repolarisation phases of the ventricular action potential, was expressed in a cell line and whole-cell currents were measured. The results obtained are presented in Table 1.1 below. A mutant form of channel D was identified in patient X who presented with increasing episodes of syncope and abnormalities in their ECG. The mutant channel was expressed in the same the cell line as in part a) and the results from whole cell recordings shown in Table 1.2. Membrane potential (mV) Peak current (nA) -60 -0.01 -50 -0.03 -40 -0.09 -30 -0.24 -20 -0.63 -10 -1.40 0 -2.32 10 -2.48 20 -1.88 30 -1.19 40 -0.69 50 -0.38 -60 TT Membrane potential Peak current (MV) (NA) 0.00 -50 -40 -30 -20 -10 -0.01 -0.06 -0.31 -1.31 -3.51 -4.27 10 20 30 40 -3.20 -2.04 -1.22 -0.69 -0.38 50 Table 1.2. Peak currents measured at different membrane potentials for a mutant form of Channel D; the holding potential was -80 mV. Table 1.1. Peak currents measured at different membrane potentials after stepping from a holding potential of -80 mV. Q 1a. Generate a current-voltage relationship plot using these values. Describe the plot and discuss whether Channel D is more likely to represent the current-voltage relationship of a voltage-gated calcium channel or voltage-gated sodium channel. Q 1b. Generate a current-voltage plot using these values. Describe and compare your plot from part (b) with the plot generated in part (a). [20 marks] [20 marks]

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i found this past paper however i cannot find the solutions, please can you answer question 1b

Section A
QUESTION 1 - Answer ALL PARTS of this question.
[100 marks total]
Experiments were designed to investigate how a potential therapeutic compound,
Compound A123, affects the plateau and repolarisation phases of the ventricular action
potential. In initial experiments, Channel D, which is known to play a significant role in the
plateau and repolarisation phases of the ventricular action potential, was expressed in a cell
line and whole-cell currents were measured. The results obtained are presented in Table
1.1 below.
A mutant form of channel D was identified in patient X who presented with increasing
episodes of syncope and abnormalities in their ECG. The mutant channel was expressed in
the same the cell line as in part a) and the results from whole cell recordings shown in
Table 1.2.
Membrane potential
(mV)
Peak current (nA)
-60
-0.01
-50
-0.03
-40
-0.09
-30
-0.24
-20
-0.63
-10
-1.40
0
-2.32
10
-2.48
20
-1.88
30
-1.19
40
-0.69
50
-0.38
-60
TT
Membrane potential
Peak current
(MV)
(NA)
0.00
-50
-40
-30
-20
-10
-0.01
-0.06
-0.31
-1.31
-3.51
-4.27
10
20
30
40
-3.20
-2.04
-1.22
-0.69
-0.38
50
Table 1.2. Peak currents measured at different membrane potentials for a mutant
form of Channel D; the holding potential was -80 mV.
Table 1.1. Peak currents measured at different membrane potentials after stepping
from a holding potential of -80 mV.
Q 1a. Generate a current-voltage relationship plot using these values. Describe the plot
and discuss whether Channel D is more likely to represent the current-voltage
relationship of a voltage-gated calcium channel or voltage-gated sodium channel.
Q 1b. Generate a current-voltage plot using these values. Describe and compare your plot
from part (b) with the plot generated in part (a).
[20 marks]
[20 marks]
Transcribed Image Text:Section A QUESTION 1 - Answer ALL PARTS of this question. [100 marks total] Experiments were designed to investigate how a potential therapeutic compound, Compound A123, affects the plateau and repolarisation phases of the ventricular action potential. In initial experiments, Channel D, which is known to play a significant role in the plateau and repolarisation phases of the ventricular action potential, was expressed in a cell line and whole-cell currents were measured. The results obtained are presented in Table 1.1 below. A mutant form of channel D was identified in patient X who presented with increasing episodes of syncope and abnormalities in their ECG. The mutant channel was expressed in the same the cell line as in part a) and the results from whole cell recordings shown in Table 1.2. Membrane potential (mV) Peak current (nA) -60 -0.01 -50 -0.03 -40 -0.09 -30 -0.24 -20 -0.63 -10 -1.40 0 -2.32 10 -2.48 20 -1.88 30 -1.19 40 -0.69 50 -0.38 -60 TT Membrane potential Peak current (MV) (NA) 0.00 -50 -40 -30 -20 -10 -0.01 -0.06 -0.31 -1.31 -3.51 -4.27 10 20 30 40 -3.20 -2.04 -1.22 -0.69 -0.38 50 Table 1.2. Peak currents measured at different membrane potentials for a mutant form of Channel D; the holding potential was -80 mV. Table 1.1. Peak currents measured at different membrane potentials after stepping from a holding potential of -80 mV. Q 1a. Generate a current-voltage relationship plot using these values. Describe the plot and discuss whether Channel D is more likely to represent the current-voltage relationship of a voltage-gated calcium channel or voltage-gated sodium channel. Q 1b. Generate a current-voltage plot using these values. Describe and compare your plot from part (b) with the plot generated in part (a). [20 marks] [20 marks]
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