Some of the electron transport carriers (the cytochromes) absorb light at characteristic wavelengths when they are carrying the extra electron from NADH but not when they give up the electrons to the next carrier. Thus, light absorption bands are all present when mitochondria are incubated in the absence of oxygen or when tyanide is present. Cyanide blocks the transfer of electrons from the last cytochrome to oxygen. When cyanide is absent and oxygen is introduced, the cytochromes stop absorbing light. There are three cytochromes in animal mitochondria, called a, b, and c. Another inhibitor of mitochor rial electron transfer is urethane. When urethane is added to aerobic mitochondria, cytochrome b begins to absorb light, but a and c do not. Finally, purified cytochrome c, even in the presence of oxygen, continues to absorb light. Use these observations to decide the order in which the cytochromes occur in the mitochondria.

TOM A given enzyme is able to utilize five different substrates. The Km's have measured for each substrate. Which substrate is most likely the biochemi relevant one in the cell? In other words, which one is most likely the pred vivo substrate for this enzyme? (Choose the one best answer). Substrate 1 with KM= 4.7 × 10-1 M. Substrate 2 with Km = 1.5 × 10-2 M. Substrate 3 with KM = 1.5 x 10-8 M. × Substrate 4 with Km= 4.7 × 10-³ M Substrate 5 with KM = 4. 7 × 10-5 M

Describe the process of the electron transport chain. Include the role of the poton motive force, electron carriers, terminal electron acceptor. Where is the ETC located in euakryotes? where is it located  in some prokaryotes? Do all organisms possess ETC?

oxidation of NADH by nitrate produces 5 ATP, by H2S is 2 ATP, by O2 is 3 ATP. Why oxidation of NADH by nitrate could produce more ATP, whereas by H2S is less.

The anaerobic, chemoautotrophic archaeobacterium Methanococcus jannaschii uses which of the following carbon-fixation pathways to obtain organic carbon from CO2? the Hill reaction the reductive acetyl-CoA pathway the Calvin cycle oxygenic photosynthesis the Krebs cycle

Cancer cells need more DNA synthesis but the NADPH/ NADP* ratio is high. Which of the following statement is TRUE? Flux through the oxidative reactions is low and the nonoxidative reactions are reversed in order to form ribose 5-phosphate. O b. The oxidative reactions and the isomerase supply both ribose 5-phosphate and NADPH with little flux through the nonoxidative branch. O C. Flux through the oxidative reactions increases and ribose 5-phosphate is shunted into glycolysis by the nonoxidative reactions. Od. The ribose 5-phosphate is recycled through the oxidative steps via the nonoxidative reactions and gluconeogenesis.

Name the three processes circled, say where they occur/how they relate, and what their significant contribution is?

Cell membranes are required for electron transfer phosphorylation. Thylakoid membranes in chloroplasts serve this purpose in photosynthetic eukaryotes. Prokaryotic cells do not have this organelle, but many are photosynthesizers. How do you think they carry out the light-dependent reactions, given that they have no chloroplasts? (What structure do they use instead?) Please and Thank You

The electron transport train relies on electron carriers NADH and FADH2 to function normally. An experiment was conducted to determine the efficiency of both carriers. In the first trial, NADH was removed, and in the second trial, FADH2 was removed. If both trials were given the same amount of substrate, which is likely to produce more energy and why? Include the role of the various ETC complexes.

In chloroplasts, protons are pumped out of thestroma across the thylakoid membrane, whereas in mito-chondria, they are pumped out of the matrix across thecrista membrane. Explain how this arrangement allowschloroplasts to generate a larger proton gradient acrossthe thylakoid membrane than mitochondria can generateacross the inner membrane.