In the Reoxidation of QH₂ by Purified Ubiquinone-Cytochrome C Reductase

question 33

Multiple Choice

In the reoxidation of QH₂ by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH₂ because:

• A) cytochrome c is a one-electron acceptor, whereas QH₂ is a two-electron donor.
• B) cytochrome c is a two-electron acceptor, whereas QH₂ is a one-electron donor.
• C) cytochrome c is water soluble and operates between the inner and outer mitochondrial membranes
• D) heart muscle has a high rate of oxidative metabolism, and therefore requires twice as much cytochrome c as QH₂ for electron transfer to proceed normally.
• E) two molecules of cytochrome c must first combine physically before they are catalytically active.

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Definitions:

Salivary Amylase

Salivary amylase is an enzyme secreted by the salivary glands that begins the digestive process by breaking down starch into simpler sugars.

Starch Digestion

The process by which dietary starch is broken down into simpler sugars, like glucose, by the action of enzymes.

Parotid Glands

The largest salivary glands, located near the ears, that produce saliva to aid in digestion.

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The process involving cells responsible for bone formation and mineralization.