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Flashcards in Biochemistry-ETC Deck (14)

Why is quinone able to freely migrate through the inner membrane of mitochondria?

It has a long lipophilic side chain.


Why isn't Hb considered a cytochrome if it has a heme group?

A heme is a protein that contains heme and carries out electron transport


Which cytochrome is the only one without His ligand that block O2 binding to heme Fe?

Cytochrome a3. This is because this is the site where the ETC reduces oxygen


How does Cyt C transfer electrons to O2?

It first moves them to the Cu of the cytochrome oxidase. The electrons then move to Cyt a within cytochrome oxidase and on to Cyt a3. These then move to O2, reduce it, produces H2O and releases 4H.


How many electrons are needed to reduce O2 on cytochrome oxidase?



How does oxygen get reduced in stepwise fashion by cytochrom oxidase?



At what points in the ETC do rotenone/amytal, antimycin A, and CN/N3/CO inhibit electron transport?

Rotenone/amytal block complex 1. Antimycin blocks complex 3. CN/N3/CO inhibit complex IV.


Why is there not a sharp decline in [O2] upon addition of NADH to mitochondria?

Almost instantly upon addition of NADH, H+ generates a back pressure.


Why is there a rapid increase in O2 consumption upon addition of ADP?

Acceptor control. Addition of ADP allows complex V to open, allow H+ to enter create ATP and proceed with oxidative phosphorylation.


How does dinitrophenol, a diet drug, affect mitochondria and respiration when added?

Dinitrophenol is an uncoupler. It makes the membrane permeable to H+ and causes continuous flow of electrons through the system. Although electrons are flowing and energy is being burned from fat, ATP is not produced because back pressure is eliminated.


How does Maggie's oxidative respiration system change when she kicks her blankets off in the night?

The hypothalamus senses cold, activates a lipase that releases fatty acids from brown fat for oxidation. Brown fat mitochondria have thermogenin which allows free passage of H+ in and out of the mitochondrial membrane. Energy from oxidative phosphorylation is not conserved as ATP and is released as heat.


Describe the structural components of ATP synthase.

The headpiece consists of three alpha, beta pairs. The gamma subunit allows for rotation of ATP synthase.


What do hydrogens bind to in ATP synthase and get into the matrix?

Glutamate. Once glutamate is bound, it is neutral and can migrate to the matrix.


What different conformations can the binding site of ATP synthase exist in?

Loose, tight and open