Question 1 2 points possible (graded) Consider an experimental setup in which mi

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Question 1 2 points possible (graded) Consider an experimental setup in which mitochondria are placed in a buffer containing ADP and inorganic phosphate inside a chamber that allows the concentration of O2 to be continuously monitored. At the times indicated by each arrow, the reagent specified is added to the chamber. Note that after each addition of reagent, previously added reagents are still present and that the concentrations of these reagents does not significantly decrease over the course of the experiment.
Graph of oxygen concentration (y-axis) vs time (x-axis). NADH, rotenone, and FADH2 are sequentially added. Oxygen concentration is initially high, then declines on addition of NADH. Oxygen concentration stops declining when rotenone is added. Oxygen concentration declines again when FADH2 is added. Part 1. Why does the rate of O2 consumption increase upon addition of NADH?

A. NADH reduces complex I, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. B. NADH reduces complex II, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. C. NADH reduces complex III, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. D. NADH reduces complex IV, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. unanswered Part 2. Based on the experimental results, propose a mechanism by which rotenone inhibits O2 consumption. Remember to consider why oxygen consumption resumes when FADH2 is added.

A. Rotenone prevents electrons from flowing from complex I to complex II. B. Rotenone prevents complex III from receiving electrons. C. Rotenone prevents electrons from flowing from NADH to complex III. D. Rotenone prevents electrons from flowing from complex I to coenzyme Q.
Question 2 Tetramethylrhodamine (TMR) is a positively-charged fluorescent dye that easily crosses lipid membranes. It specifically labels mitochondria in living cells, but it does not label the mitochondria of dead cells. The difference in labeling is directly due to: A. differences in the reduction of complex I in the ETC. B. the loss of the pH gradient across the inner mitochondrial membrane. C. differences in the levels of ATP between the two cells. D. differences in the levels of pyruvate between the two cells.
Order the following events as they likely occurred in the evolution of eukaryotic organelles.
A. A significant rise in the percentage of oxygen in the earth’s atmosphere
B. Evolution of aerobic bacteria
C. Evolution of cyanobacteria (photosynthetic bacteria)
D. The appearance of mitochondria in eukaryotes
1. 1st event A, B, c, D 2. 2nd event A, B, c, D
3. 3rd event A, B, c, D 4. 4th event A, B, c, D

Question 1 2 points possible (graded) Consider an experimental setup in which mitochondria are placed in a buffer containing ADP and inorganic phosphate inside a chamber that allows the concentration of O2 to be continuously monitored. At the times indicated by each arrow, the reagent specified is added to the chamber. Note that after each addition of reagent, previously added reagents are still present and that the concentrations of these reagents does not significantly decrease over the course of the experiment.
Graph of oxygen concentration (y-axis) vs time (x-axis). NADH, rotenone, and FADH2 are sequentially added. Oxygen concentration is initially high, then declines on addition of NADH. Oxygen concentration stops declining when rotenone is added. Oxygen concentration declines again when FADH2 is added. Part 1. Why does the rate of O2 consumption increase upon addition of NADH?

A. NADH reduces complex I, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. B. NADH reduces complex II, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. C. NADH reduces complex III, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. D. NADH reduces complex IV, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. unanswered Part 2. Based on the experimental results, propose a mechanism by which rotenone inhibits O2 consumption. Remember to consider why oxygen consumption resumes when FADH2 is added.

A. Rotenone prevents electrons from flowing from complex I to complex II. B. Rotenone prevents complex III from receiving electrons. C. Rotenone prevents electrons from flowing from NADH to complex III. D. Rotenone prevents electrons from flowing from complex I to coenzyme Q.
Question 2 Tetramethylrhodamine (TMR) is a positively-charged fluorescent dye that easily crosses lipid membranes. It specifically labels mitochondria in living cells, but it does not label the mitochondria of dead cells. The difference in labeling is directly due to: A. differences in the reduction of complex I in the ETC. B. the loss of the pH gradient across the inner mitochondrial membrane. C. differences in the levels of ATP between the two cells. D. differences in the levels of pyruvate between the two cells.
Order the following events as they likely occurred in the evolution of eukaryotic organelles.
A. A significant rise in the percentage of oxygen in the earth’s atmosphere
B. Evolution of aerobic bacteria
C. Evolution of cyanobacteria (photosynthetic bacteria)
D. The appearance of mitochondria in eukaryotes
1. 1st event A, B, c, D 2. 2nd event A, B, c, D
3. 3rd event A, B, c, D 4. 4th event A, B, c, D

Question 1 2 points possible (graded) Consider an experimental setup in which mitochondria are placed in a buffer containing ADP and inorganic phosphate inside a chamber that allows the concentration of O2 to be continuously monitored. At the times indicated by each arrow, the reagent specified is added to the chamber. Note that after each addition of reagent, previously added reagents are still present and that the concentrations of these reagents does not significantly decrease over the course of the experiment.
Graph of oxygen concentration (y-axis) vs time (x-axis). NADH, rotenone, and FADH2 are sequentially added. Oxygen concentration is initially high, then declines on addition of NADH. Oxygen concentration stops declining when rotenone is added. Oxygen concentration declines again when FADH2 is added. Part 1. Why does the rate of O2 consumption increase upon addition of NADH?

A. NADH reduces complex I, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. B. NADH reduces complex II, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. C. NADH reduces complex III, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. D. NADH reduces complex IV, after which electrons are passed down the ETC until they ultimately reduce oxygen to generate water. unanswered Part 2. Based on the experimental results, propose a mechanism by which rotenone inhibits O2 consumption. Remember to consider why oxygen consumption resumes when FADH2 is added.

A. Rotenone prevents electrons from flowing from complex I to complex II. B. Rotenone prevents complex III from receiving electrons. C. Rotenone prevents electrons from flowing from NADH to complex III. D. Rotenone prevents electrons from flowing from complex I to coenzyme Q.
Question 2 Tetramethylrhodamine (TMR) is a positively-charged fluorescent dye that easily crosses lipid membranes. It specifically labels mitochondria in living cells, but it does not label the mitochondria of dead cells. The difference in labeling is directly due to: A. differences in the reduction of complex I in the ETC. B. the loss of the pH gradient across the inner mitochondrial membrane. C. differences in the levels of ATP between the two cells. D. differences in the levels of pyruvate between the two cells. Question 2 Tetramethylrhodamine (TMR) is a positively-charged fluorescent dye that easily crosses lipid membranes. It specifically labels mitochondria in living cells, but it does not label the mitochondria of dead cells. The difference in labeling is directly due to: A. differences in the reduction of complex I in the ETC. B. the loss of the pH gradient across the inner mitochondrial membrane. C. differences in the levels of ATP between the two cells. D. differences in the levels of pyruvate between the two cells.
Order the following events as they likely occurred in the evolution of eukaryotic organelles.
A. A significant rise in the percentage of oxygen in the earth’s atmosphere
B. Evolution of aerobic bacteria
C. Evolution of cyanobacteria (photosynthetic bacteria)
D. The appearance of mitochondria in eukaryotes
1. 1st event A, B, c, D 2. 2nd event A, B, c, D
3. 3rd event A, B, c, D 4. 4th event Order the following events as they likely occurred in the evolution of eukaryotic organelles.
A. A significant rise in the percentage of oxygen in the earth’s atmosphere
B. Evolution of aerobic bacteria
C. Evolution of cyanobacteria (photosynthetic bacteria)
D. The appearance of mitochondria in eukaryotes
1. 1st event A, B, c, D 2. 2nd event A, B, c, D
3. 3rd event A, B, c, D 4. 4th event A, B, c, D

Explanation / Answer

Part 1.

Answer A.

NADH reduces complex to get converted into NAD+. These electrons transferrred from NADH functions in the reduction of Oxygen molecule.

Thus on Addition of NADH rate of consumption of Oxygen increases. The correct answer is option A, NADH reduces complex I, after which electrons are passed down the ETC until they ultimately reduce Oxygen to generate water.

Answer B. Rotenone is a metabolic inhibitor which work by interfering the electron transport chain. It interfere transfer of electrons from iron-sulfur center in complex I to Ubiquinone. Hence correct option is D, Rotenone prevents electrons from flowing from complex I to coenzyme Q.

Question 2:

Part A: Tetramethylrhodamine (TMR) is a positively-charged fluorescent dye that easily crosses lipid membranes. It specifically labels mitochondria in living cells, but it does not label the mitochondria of dead cells. This dye is dependent on membrane potential for its fluroscence and thus do not appear in mitcochondira of dead cells. Hence to correct option is B, the loss of the pH gradient across the inner mitochondrial membrane.

Part B:

During early earth all living froms were anaerobic, with the evolution of cyanobacteria, atmosphere become rich with Oxygen resulting in evolution of aerobic life. Thus the correct sequence would be.

C. Evolution of cyanobacteria (photosynthetic bacteria)

A significant rise in the percentage of oxygen in the earth’s atmosphere

B.Evolution of aerobic bacteria

D.The appearance of mitochondria in eukaryotes

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