The electron carry chains that bacteria (prokaryotes) run in plasma membrane (mitochondria are missing in prokaryotes). Some bacterial electron deliver chains resemble the mitochondrial electron deliver chain. Paracoccus denitrificans is a gram-negative, facultative anaerobic soil bacterium.

It is a model prokaryote for research studies of respiration. Once this bacterium grows aerobically, the electron transfer chain possesses four complexes the correspond come the mitochondrial chain.

But, once this bacterium grow anaerobically v nitrate as its electron acceptor, the chain is structured rather differently. Due to the fact that most bacteria flourish anaerobically making use of different range of electron acceptor substances, the bacter electron carry chains room frequently an extremely different.

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Bacterial electron deliver chains vary in your electron carrier (e.g., in your cytochromes) and are usually extensively branched. Electrons often go into at numerous points and also leave through several terminal oxidases. Bacterial electron transfer chains are usually shorter and possess lower phosphorus come oxygen (P/O) ratios than mitochondrial deliver chain.

Thus bacter (prokaryotic) and mitochondrial (eukaryotic) electron move chains differ in details of construction although they operate employing the same basic principles. For convenience, a streamlined view that the electron move chain of Escherichia coli is being provided here regarding show these differences (Fig. 24.7).


Although the electron transfer chain of E. Coli transports electrons from NADH (NADH is the electron donor) come acceptors and moves protons (H+) throughout the plasma membrane similar to mitochondrial electron transfer chain, it is quite different from the latter in the construction. E. Coli carry chain is short, is composed of 2 branches (cytochrome d branch and cytochrome o branch), and a quite different variety of cytochromes (e.g., Cyt b558, Cytb562, Cyt d, Cyt o).

Coenzyme Q (ubiquinone) carries electrons and donates them to both branches, yet the branches run under different growth conditions. The cytochrome d branch shows really high affinity because that oxygen and operates at low oxygen level (low aeration) usually when the bacterium is in stationary step of growth.

This branch is not as efficient as the cytochrome o branch since it does not actively pump proton to periplasmic space.

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The cytochrome o branch shows moderately high efficiency for oxygen and operates in ~ high oxygen concentrations (high aeration). This branch operates typically when the bacterium is in log phase of its development (i.e., cultivation rapidly), and actively pumps protons (H+) in the periplasmic space.