EXPERIMENT 1 EXPERIMENT 2 Step 3 1.5 Step 3 1.5 Step 1 Step 1 0.5 0,5 Step 2 V, mV V, mV Step 2 -100 -75 -50 -25 0 25 50 -100 -75 -25 0 25 -50 50 EXPERIMENT 3 Step 1 EXPERIMENT 4 Step 1 Step 3 Step 3 Step 4 0.6 0.8 Step 2 76.2 0.2 V, mV v, mv Step 2 -100 -75 -50 -25 0 25 50 -100 -75 -50 -25 0 25 50 I, nA I, nA I, nA I, nA
(Plant Physiology)
Electrophysiological measurements were carried out on bean guard cells to measure outwards K+ currents and how they are modified by various factors. Assume that the K+ currents shown here are proportional to the net changes in the intracellular K+ concentration.
Currents (I) across the plasma membrane at different voltages (V) were determined after each step of four different experiments.
Experiment 1
Step 1: Incubated in washing buffer. Step 2: Exposed to exogenous nitric oxide (NO). Step 3: Washed in washing buffer
Experiment 2
Step 1: Injected with buffer to set cytoplasmic pH to 7.4. Step 2: Exposed to exogenous nitric oxide (NO). Step 3: Washed in washing buffer.
Experiment 3
Step 1: Incubated in washing buffer. Step 2: Exposed to exogenous nitric oxide (NO). Step 3: Exposed to BAL, a reducing agent that is known to reduce disulphide bridges in proteins. Step 4: Exposed to exogenous nitric oxide (NO).
Experiment 4
Step 1: Incubated in washing buffer. Step 2: Exposed to PAO, an oxidising agent that localises to membranes within the cell. Step 3: Washed in washing buffer containing 0.3mM BAL
The attached figure shows the experimental results.
How does NO, cytoplasmic pH, BAL and PAO affect stomata movement?
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