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Americans are fatter than ever and processed food is to blame
Before diving into this article we need to clarify how being obese is measured. There are many ways to...
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Through the Microscope updates
An important feature of Through the Microscope is the animations that depict important processes. Often...
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Obesity and the Microbiome
A large body of evidence is emerging showing that the microbiome has a role in obesity and I cover some...
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New updates to Why Microbes Matter
Chapters 4, 5, 8, 10, and 14 of Why Microbes Matter have been updated to reflect some new information...
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The very real danger of alfatoxins
Food products, especially harvested grains, need to be stored carefully. Proper management means storing...
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Figure 9.10. Electron transport in Rhodobacter sphaeroides. Light is collected through the light-harvesting complexes and excites a special pair of BChl that sits near the periplasm. As this excites, the special pair relaxes and an electron is ejected, reducing the nearby bacteriopheophytin. From here the electron travels toward the cytoplasm where it eventually reduces quinone B near the cytoplasmic side of the membrane. The reduction of quinone B also consumes one proton from the cytoplasm. A second round of excitation of the special pair brings a second electron to quinone B that picks up another proton from the cytoplasm and diffuses away from the reaction center and into the quinone pool of the membrane. This reduced quinone then is oxidized at the cytochrome b/c1 complex in a similar fashion as to what is observed in oxidative phosphorylation. The reduction of quinone B and its oxidation at the cytochrome b/c1 complex results in the generation of a proton motive force. That is used to generate ATP using the ever-familiar ATP synthase we discussed earlier. The low energy electrons from the b/c1 complex are then donated to cytochrome c2, and finally end up reducing the Mg atom in the special pair to complete the cycle. This process is termed cyclic photophosphorylation because the electrons travel a close circuit. Contrast this with oxidative phosphorylation where the electrons are eventually donated to oxygen.