Biochemistry-ETC Flashcards

1
Q

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

A

It has a long lipophilic side chain.

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2
Q

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

A

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

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3
Q

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

A

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

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4
Q

How does Cyt C transfer electrons to O2?

A

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.

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5
Q

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

A

4

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6
Q

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

A

*

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7
Q

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

A

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

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8
Q

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

A

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

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9
Q

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

A

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

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10
Q

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

A

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.

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11
Q

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

A

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.

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12
Q

Describe the structural components of ATP synthase.

A

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

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13
Q

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

A

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

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14
Q

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

A

Loose, tight and open

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