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Electron Carriers
Electron carriers accept electrons from substrates that are being oxidized and donate
them to the electron transport chain.
Reduction is when a compound gains one or more electrons, while oxidation is when a
compound loses one or more electrons.
Nicotinamide nucleotide-linked dehydrogenases remove 2 hydrogen atoms from
substrates, transferring one as a hydride ion (:H-) to NAD+ and the other as H+ into the
medium.
Flavoproteins accept 1 or 2 electrons, forming semiquinone or FADH2/FMNH2
respectively.
There are three types of membrane-bound electron carriers: Ubiquinone, Cytochromes, and
Iron-sulfur proteins.
Ubiquinone, also known as Coenzyme Q, is a lipid-soluble benzoquinone that transports
electrons and protons from Complexes I and II to Complex III.
Cytochromes are proteins with heme prosthetic groups containing iron, and they undergo
1-electron transfers.
Iron-sulfur proteins contain iron in association with inorganic sulfur or sulfur of Cys
residues, and they also undergo 1-electron transfers.
Electron Transport Chain and ATP Synthesis
The sulfur of Cys residues of the protein, or both, are involved in electron flow.
The direction of electron flow can be either low or high, as indicated by Fig 19-5.
Table 19-2 provides information on the four electron carrier complexes and cytochrome c.
Exergonic electron flow drives the endergonic movement of protons, generating a proton
gradient. This is shown in Fig 19-16.
In electron transport, all electrons are transferred to ubiquinone, as mentioned in Fig 19-15.
ROS production occurs in the electron transport chain, as depicted in Fig 19-18.
The proton gradient in ATP synthesis is composed of a chemical potential (pH) and
electrical potential, as shown in Fig 19-17.
The chemiosmotic model explains ATP synthesis, as described in Fig 19-19.
The chemiosmotic theory provides a simplified version of the chemiosmotic model for
ATP synthesis, as indicated in Fig 19-1.
Proton motive force drives ATP synthesis as protons flow passively back into the matrix
through the pore associated with ATP synthase.
Electron Carriers
Electron carriers accept electrons from substrates that are being oxidized and donate
them to the electron transport chain.
Reduction is when a compound gains one or more electrons, while oxidation is when a
compound loses one or more electrons.
Nicotinamide nucleotide-linked dehydrogenases remove 2 hydrogen atoms from
substrates, transferring one as a hydride ion (:H-) to NAD+ and the other as H+ into the
medium.
Flavoproteins accept 1 or 2 electrons, forming semiquinone or FADH2/FMNH2
respectively.
There are three types of membrane-bound electron carriers: Ubiquinone, Cytochromes, and
Iron-sulfur proteins.
Ubiquinone, also known as Coenzyme Q, is a lipid-soluble benzoquinone that transports
electrons and protons from Complexes I and II to Complex III.
Cytochromes are proteins with heme prosthetic groups containing iron, and they undergo
1-electron transfers.
Iron-sulfur proteins contain iron in association with inorganic sulfur or sulfur of Cys
residues, and they also undergo 1-electron transfers.
Electron Transport Chain and ATP Synthesis
The sulfur of Cys residues of the protein, or both, are involved in electron flow.
The direction of electron flow can be either low or high, as indicated by Fig 19-5.
Table 19-2 provides information on the four electron carrier complexes and cytochrome c.
Exergonic electron flow drives the endergonic movement of protons, generating a proton
gradient. This is shown in Fig 19-16.
In electron transport, all electrons are transferred to ubiquinone, as mentioned in Fig 19-15.
ROS production occurs in the electron transport chain, as depicted in Fig 19-18.
The proton gradient in ATP synthesis is composed of a chemical potential (pH) and
electrical potential, as shown in Fig 19-17.
The chemiosmotic model explains ATP synthesis, as described in Fig 19-19.
The chemiosmotic theory provides a simplified version of the chemiosmotic model for
ATP synthesis, as indicated in Fig 19-1.
Proton motive force drives ATP synthesis as protons flow passively back into the matrix
through the pore associated with ATP synthase.
