Exam 14: Energy Conversion: Mitochondria and Chloroplasts

Mitotic segregation of organelles can lead to so-called homoplasmy, when all organelles in each cell carry the same genome. In contrast, heteroplasmy describes the presence of organelles within the same cell that are different with respect to their genomic sequences. Would you expect a defect in the mitochondrial fusion machinery to favor homoplasmy (M) or heteroplasmy (T)? Write down M or T as your answer. Answers

A hypothetical electron-transport chain contains an electron donor (1), an electron carrier (2), and an electron acceptor (3). Which of these molecules has the highest redox potential? Write down 1, 2, or 3 as your answer.

Sort the following molecules to reflect the order in which they transfer electrons in noncyclic photophosphorylation in plants. Your answer would be an eight-letter string composed of letters A to H only, e.g. FCDEHGBA. (A) Ferredoxin-NADP? reductase (B) Plastoquinone (C) Ferredoxin (D) Cytochrome b?-f complex (E) H?O (F) Plastocyanin (G) Photosystem I (H) Photosystem II

The electrons used in carbon fixation by chloroplasts ultimately come from …

Some photosynthetic bacteria have only one type of photosystem in their plasma membrane. Which of the following is likely to be true regarding such bacteria?

Which of the following probably occurred first on Earth?

Indicate whether each of the following descriptions better applies to chloroplasts (C) or mitochondria (M). Your answer would be a five-letter string composed of letters C and M only, e.g. MMMMC. ( ) Extensive editing occurs on their RNAs. ( ) They utilize dynamin-like GTPases to divide from the outside. ( ) The organization of gene clusters in their genome is strikingly similar to cyanobacteria. ( ) They typically have larger genomes. ( ) They have a more ancient endosymbiotic relationship with their host.

A facultative anaerobic bacterium can survive both aerobic and anaerobic conditions. Under both conditions, the cell maintains a proton-motive force across the plasma membrane that drives many cellular processes including nutrient import. Under aerobic conditions, the proton-motive force is produced by a respiratory chain. What is the mode of action of the plasma membrane ATP synthase in this bacterium under aerobic conditions: ATP-hydrolysis mode (H) or ATP-synthesis mode (S)? Write down H or S as your answer.

ATP synthase molecules in mitochondria form dimers that are localized mostly to sharp cristae ridges. What should happen if subunits of the synthase that are required for dimerization are mutated in yeast?