Andrea: Exam 4 Oxidative Phosphorylation

This set of flashcards covers the key concepts related to oxidative phosphorylation, including the processes of cellular respiration, electron transport, and ATP synthesis.

What is cellular respiration?

A process of metabolic reactions that take place in cells to convert chemical energy from nutrients and oxygen to ATP, H2O, and CO2.

What are the three stages of cellular respiration?

Acetyl-CoA production, Acetyl-CoA oxidation, and the Respiratory chain.

What role does the mitochondria play in eukaryotic aerobic metabolism?

It plays a central role in oxidative phosphorylation and ATP synthesis.

What are the main electron donors in oxidative phosphorylation?

NADH and FADH2.

What is the final electron acceptor in oxidative phosphorylation?

O2 (oxygen).

What is the role of the respiratory chain?

Electrons flow through a series of membrane-bound carriers to reduce O2 to H2O and drive ATP production.

What is the chemiosmotic model?

It suggests that the proton motive force drives ATP synthesis.

How does ATP synthase function?

It synthesizes ATP from ADP and inorganic phosphate as protons flow down their electrochemical gradient.

What is the overall driving force for ATP synthesis?

The proton-motive force.

What are the four types of electron carrying molecules?

NAD and flavoproteins, Ubiquinone (coenzyme Q), cytochromes, and iron-sulfur proteins.

What is the role of ubiquinone in the respiratory chain?

It shuttles reducing equivalents between less mobile electron carriers and plays a central role in coupling electron flow to proton movement.

What is the Q cycle?

A mechanism in Complex III that describes the transfer of electrons and protons between ubiquinone and cytochrome c.

What is Complex I of the mitochondrial respiratory chain?

It transfers electrons from NADH to ubiquinone, also known as NADH:ubiquinone oxidoreductase.

What is the role of Complex II?

It transfers electrons from succinate to ubiquinone.

Where do most electrons for oxidative phosphorylation come from?

From dehydrogenase activity.

What is the importance of the proton gradient?

It drives ATP synthesis via the movement of protons through ATP synthase.

How does the respiratory chain create a proton gradient?

By pumping protons from the mitochondrial matrix into the intermembrane space.

Which complex does not pump protons?

Complex II.

What drives the movement of protons in ATP synthesis?

The electrochemical gradient.

What is the initial substrate for ATP synthesis by ATP synthase?

ADP and inorganic phosphate (Pi).

What happens to ATP synthesis if the proton gradient is dissipated?

ATP synthesis will stop as there's no driving force for the protons to flow back into the matrix.

What is the effect of cyanide on cellular respiration?

It blocks electron transfer between Complex IV and O2, halting respiration and ATP synthesis.

What function does DNP serve in cellular respiration?

It acts as an uncoupler, allowing respiration to continue without ATP synthesis.

What is the process of converting succinate in the citric acid cycle?

It involves succinate dehydrogenase, which is Complex II of the respiratory chain.

What can happen to individuals with mutations in heme b or Q binding sites?

They may develop hereditary paraganglioma, a benign tumor.

What characterizes iron-sulfur proteins?

They are associated with sulfur atoms and can transfer one electron at a time.

How do protons affect ATP synthase?

Protons moving through the Fo complex cause conformational changes that drive ATP synthesis.

What are the key components of an ATP synthase complex?

Fo component (integral membrane part) and F1 component (peripheral part that synthesizes ATP).

What is the relationship between ATP synthesis and electron transport?

Both processes are coupled; electron transport creates a proton gradient needed for ATP synthesis.

How do the different conformations of F1 subunits affect ATP synthesis?

They provide distinct binding sites for ATP and ADP, cycling between states during ATP production.

What is the importance of the Eʹo values in electron transfer?

They determine the direction of electron flow from lower to higher reduction potentials.

What happens when there is a high concentration of protons outside the mitochondrial matrix?

It creates a strong electrochemical gradient promoting the flow of protons back into the matrix.

What indicates that ATP synthase is a reversible enzyme?

It can catalyze ATP synthesis and hydrolysis, with zero net change in free energy.

What is the expected proton motive force for ATP synthesis?

It is driven by a transmembrane H+ gradient resulting from electron transport.

What happens during the uncoupling of oxidation and phosphorylation?

Electron transfer continues, but ATP synthesis stops due to a loss of the proton gradient.

What is the typical rate of rotation for the ATP synthase c ring?

About 6,000 revolutions per minute (rpm).

What does the P/O ratio indicate?

It denotes the number of ATP molecules synthesized per amount of oxygen consumed.

What is the role of Mg2+ in ATP synthesis?

It stabilizes the interaction between ATP and the active sites of ATP synthase.

In the binding-change model, how does the g subunit influence ATP synthesis?

Its rotation helps different beta subunits assume states that bind ADP or release ATP.

What is the outcome of the complete rotation of the g subunit in ATP synthase?

It's capable of synthesizing three ATP molecules per full rotation.

What factors can cause the mitochondrial membrane to be disrupted?

Chemical uncouplers or physical shearing can disrupt the inner mitochondrial membrane.