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3 Cellular Respiration Virtual Lab 17 September 2020 Jason Bao Cellular Respiration Virtual Lab

Control Data Healthy Muscle Cells Pyruvate

0.12 mM

NADH

0.30 mM

Intermembrane H+

0.32 mM

Jared’s Cell Data

Pyruvate concentration stays constant.

NADH concentration increases.

Intermembrane H+ Concentration decreases.

Healthy Muscle Cells

Jared’s Muscle Cells

Pyruvate

0.12 mM

0.12 mM

NADH

0.30 mM

0.50 mM

Intermembrane H+

0.32 mM

0.05 mM

Hypothesis: Choose the poison you think was given to Jared: Cyanide Explain how the data supports your hypothesis: The data supports the hypothesis that Jared was poisoned with cyanide as Jared’s muscle cells severely lack H+ in the intermembrane space, protons that the Electron Transport Chain provide when NADH and FADH2 drop off their electrons. However, since the data indicates a high concentration of NADH and a low concentration of intermembrane H+, the ETC must have halted, which the poison cyanide does by attaching to the last enzyme of the ETC.

Experiments: Measuring changes in concentration of pyruvate, NADH, and intermembrane H+ after each poison injected into muscle cells 2-deoxyglucose – all decrease Arsenic – pyruvate increase, others decrease Cyanide – pyruvate no change, NADH increase, H+ decrease Oligomycin – pyruvate and NADH no change, H+ increase

Review: Final Hypothesis – Cyanide was used to poison to Jared’s cells. Antidote – antidote changes cyanide to molecule called thiocyanate, which the body can remove through urine.

Case Summary: Background Explain how cyanide caused Jared’s symptoms (e.g., muscle weakness). The cyanide attaches itself to the last enzyme of the ETC, which halts the processes of the chain. As such, the ETC is unable to pump the hydrogen ions across the inner mitochondrial membrane and create a proton gradient as evidenced in the low H+ concentration in the intermembrane. Because of this, very little if any ATP is produced when the protons flow back across the membrane through ATP synthase, which would contribute to Jared’s symptoms of muscle weakness, shortness of breath, and dizziness.

Data Explain how the data from your experiments showed that cyanide was used to poison Jared, and that 2-deoxyglucose, arsenic and oligomycin were not used. The data showed that cyanide poisoned Jared rather than the other 3 poisons as the relative changes in pyruvate, NADH, and intermembrane H+ concentrations in Jared’s muscle cells in comparison to the control (healthy) muscle cells of no change, increase, and decrease (respectively) only matched the changes seen in the cyanide trial. Specifically, 2-deoxyglucose created a decreased in pyruvate concentration, arsenic caused pyruvate concentration to increase and NADH concentration to decrease, and oligomycin created an H+ increase as seen in the data from the experiment step of the experiment. As such, only cyanide’s results paralleled the observations seen in Jared’s muscle cells so the scientist could determine that cyanide was used to poison Jared. Poisons For each molecule of glucose, glycolysis only makes 2 ATP, the Krebs cycle only makes 2 ATP and the ETC makes 34 ATP. If the suspects had given Jared the 2-deoxyglucose poison, would the decrease in ATP concentration be smaller, the same or larger as when they used cyanide? Explain your answer. The decrease in ATP concentration would be larger than if they used cyanide as with cyanide, only the final step of ATP production would be hampered in that the ETC is produce the 34 ATP from the proton movement through the ATP synthase. However, since 2-deoxyglucose attaches to the first enzyme of glycolysis, it halts the process and prevents the production of the 2 pyruvate molecules, which creates a loss of the 2 ATP released from glycolysis and Krebs cycle in addition to the 34 ATP of the ECT as without pyruvate and thus the NADH and FADH2 of the Krebs cycle, the ECT cannot perform its function. In fact, since ATP must be inputted into glycolysis for the first enzyme to operate, there would be a net loss of 34 + 2 + 2 + 1 = 39 ATP with 2-deoxyglucose poison versus the 34 ATP of cyanide so the decrease in ATP concentration would be much larger. Conclusions Describe how the antidote helped Jared's cells make ATP (include the ETC and H+ gradient in your answer). The antidote helped Jared’s cells make ATP again as the antidote changed cyanide into thiocyanate which the body can remove through urine. With the removal of cyanide from the ETC, the ETC can pump a sufficient number of protons across the H+ gradient which can later flow back through ATP synthase to create ATP once again.