CH 21: The Proton-Motive Force

Flashcards on Chapter 21: The Proton-Motive Force in Biochemistry.

The proton-motive force.

What is the proton gradient generated by the oxidation of NADH and FADH2 called?

Δp = chemical gradient (ΔpH) + charge gradient (ΔΨ).

What is the equation for proton-motive force (Δp)?

ATP synthases that bind to one another to form dimers.

What contributes to the formation of cristae?

F0 component (proton-conducting unit) and F1 component (catalytic unit).

What are the two components of ATP synthase?

Embedded in the inner mitochondrial membrane.

Where is the F0 component of ATP synthase located?

Three forms: Open (O), Loose (L), and Tight (T).

What do the three catalytic β subunits of the F1 component exist in?

Nucleotides and orthophosphate can bind or be released.

What happens during the open (O) conformation of the β subunit?

Nucleotides are trapped in the active site.

What occurs during the loose (L) conformation of the β subunit?

ATP from ADP and Pi.

What is synthesized during the tight (T) conformation of the β subunit?

The rotation of the c ring driven by the proton gradient.

What powers ATP synthesis around the c ring?

The number of c subunits in the c ring.

What determines the number of protons required to synthesize a molecule of ATP?

Glycerol phosphate shuttle.

Which shuttle is used by electrons from cytoplasmic NADH in muscle?

They are transferred to FADH2.

What is the fate of electrons transferred from NADH in the glycerol phosphate shuttle?

Malate-aspartate shuttle.

Which shuttle is involved in generating mitochondrial NADH from cytoplasmic NADH in the heart and liver?

Exchange of cytoplasmic ADP for mitochondrial ATP.

What does the ATP–ADP translocase enable?

The proton-motive force.

What regulates the entry of ADP into mitochondria?

30 molecules of ATP.

What is the net yield of ATP from the complete oxidation of glucose?

2 ATP (net).

How much ATP is formed via glycolysis after subtracting the ATP input?

28 ATP (net).

How many molecules of ATP are formed in oxidative phosphorylation?

+2 ATP.

What is the ATP yield per molecule of glucose during glycolysis?

They donate electrons to the electron transport chain.

What roles do NADH and FADH2 play in oxidative phosphorylation?

Regulation of oxidative phosphorylation by the availability of ADP.

What is acceptor control or respiratory control?

Heat generation, a process called nonshivering thermogenesis.

What is the result of uncoupling electron transport from ATP synthesis?

Uncoupling protein 1 (UCP-1) or thermogenin.

Which protein facilitates regulated uncoupling in mitochondria?

It prevents the formation of the proton-motive force.

What effect does the inhibition of the electron-transport chain have on oxidative phosphorylation?

Proton flow is inhibited, preventing electron transport.

What happens if ATP synthase is inhibited?

They carry protons across the inner mitochondrial membrane, preventing the formation of a proton gradient.

What do uncouplers do in the context of oxidative phosphorylation?

Inhibition of the ATP–ADP translocase.

What blocks oxidative phosphorylation by preventing ATP–ADP exchange?

Eight subunits.

How many c subunits are present in the c ring of vertebrates?

It yields two more molecules of ATP per molecule of glucose oxidized.

What is the result of using malate-aspartate shuttle compared to glycerol phosphate shuttle?

It regulates the flow of fuels used in metabolism.

How does an increase in energy charge affect cellular respiration?

Nonshivering thermogenesis.

What is the process by which heat is generated due to uncoupling of oxidative phosphorylation?

The earlier value of 36 molecules of ATP.

Where does the ATP yield of 30 molecules from glucose oxidation supersede?

Acceptor control.

What metabolic control is evidenced by ADP requirement?

It directly influences how much ATP is synthesized per proton flow.

How does the proton gradient affect ATP synthesis efficiency?

It participates in proton flow to power ATP synthesis.

What is a key function performed by the c ring?