Exam 14: Energy Conversion: Mitochondria and Chloroplasts

Consider the remarkable structure of the F1Fo ATP synthase shown in the following schematic drawing. Answer the following question(s) based on the structure. -As seen from the F? head in the matrix, the rotation of the c ring is counterclockwise in the ATP-synthesis mode of the motor and clockwise in the ATP-hydrolysis mode of the motor. As shown in the above drawing, the "a subunit" (labeled 2) is part of the stator embedded in the membrane, and it forms the entry and exit sites for the protons that are bound by the rotating c ring. How do you think the two half-channels of the a subunit are arranged as seen from the c ring? Write down A or B from the following schematic diagram as your answer.

What is the main reason why atmospheric oxygen levels did not rise immediately after the mass production of the gas by photosynthetic bacteria?

Which of the following is true regarding light-harvesting complexes in plant chloroplasts?

In actively respiring mitochondria, where in the following schematic drawing of the inner and outer mitochondrial membranes would you expect to find the lowest local pH?

For mitochondria that are active in respiration, indicate whether the movement of each of the following molecules into (I) or out of (O) the matrix is thermodynamically favorable. Your answer would be a four-letter string composed of letters I and O only, e.g. IOOI. ( ) O² ( ) H⁺ ( ) ADP ( ) CO₂

Who has a different mitochondrial DNA in a family?

Which of the following is NOT universally encoded by the mitochondrial DNA?

Indicate whether each of the following descriptions better applies to photosystem I (1) or photosystem II (2). Your answer would be a four-digit number composed of digits 1 and 2 only, e.g. 2212. ( ) It reduces plastoquinone. ( ) It uses a manganese cluster to oxidize water. ( ) It is confined to unstacked thylakoids. ( ) It contains the special pair P???.

Indicate whether each of the following descriptions better applies to the light (L) or dark (D) reactions in plant chloroplasts. Your answer would be a five-letter string composed of letters L and D only, e.g. DDDLD. ( ) It produces the sugar glyceraldehyde 3-phosphate. ( ) It involves the electron-transfer chain embedded in the thylakoid membrane. ( ) It involves O₂ production. ( ) It involves fixation of CO₂. ( ) It generates ATP.

In the following schematic drawing of the inner and outer mitochondrial membranes, in what region (A to D) would you expect to find more ATP synthase dimers?

In addition to their respiratory function, mitochondria have other important roles in cellular metabolism. Which of the following processes is NOT carried out mainly by mitochondria?

Sort the following molecules to reflect the order in which they carry electrons in the respiratory chain. Your answer would be a seven-letter string composed of letters A to G only, e.g. GFADCBE. (A) NADH dehydrogenase complex (B) Cytochrome c oxidase complex (C) Cytochrome c reductase complex (D) Cytochrome c (E) Ubiquinone (F) NADH (G) H?O

In the following simplified diagram of the Calvin cycle, which step (A to E) is catalyzed by the abundant enzyme Rubisco?

Two haploid budding yeast cells are allowed to mate. One of them carries a mutation in its mitochondrial DNA that makes the yeast cell resistant to an antifungal drug. If the resulting diploid zygote is allowed to propagate (in the absence of the drug), how do you predict that the fraction of drug-resistant cells will change over time in the population? Choose the best curve (A to F) from the following graph. Note that the "population" is only composed of one cell at the beginning of the experiment. The curves are smoothened to cancel stochastic fluctuations that happen at such low population sizes.

Consider the remarkable structure of the F1Fo ATP synthase shown in the following schematic drawing. Answer the following question(s) based on the structure. -In Escherichia coli, the c ring of ATP synthase is composed of 12 c subunits. For one fully productive revolution of this ring, how many protons are transported across the membrane for each molecule of ATP produced? Write down your answer as a number, rounded to the nearest integer, e.g. 17.

Which of the following molecules can serve as the terminal electron acceptor in bacterial electron-transport chains?

The free-energy change for ATP hydrolysis to ADP inside the cell is about -50 kJ/mole. The complete cellular oxidation of glucose to carbon dioxide and water has a free-energy change of about -3000 kJ/mole. What is the efficiency of the cellular metabolism in harvesting this amount of free energy in the form of ATP synthesis?

The water-splitting step in photosynthesis …

Indicate whether each of the following descriptions better applies to the genome of mitochondria (M) or nuclei (N) in vertebrates. Your answer would be a four-letter string composed of letters M and N only, e.g. MNMN. ( ) It has a higher percentage of noncoding DNA. ( ) It has a stricter codon usage. ( ) Its genes are present at higher copy numbers per cell. ( ) Its evolutionary clock ticks much faster.

Consider the remarkable structure of the F1Fo ATP synthase shown in the following schematic drawing. Answer the following question(s) based on the structure. -With about 7000 c-ring revolutions per minute, on average how many moles of these pumps should be working at each moment in an entire human body to make about 50 kilograms of ATP per day? The molecular weight of ATP is about 500.