Energy Generation in Mitochondria and Chloroplasts

These flashcards cover key concepts related to energy generation in mitochondria and chloroplasts, focusing on structures, processes, and evolutionary significance.

What are the three main components of a mitochondrion?

Outer membrane, inner membrane, and two internal compartments.

What cycle generates high-energy electrons required for ATP production?

The Citric Acid Cycle.

What does the movement of electrons in mitochondria couple with?

The pumping of protons.

How many large enzyme complexes do electrons pass through in the inner mitochondrial membrane?

Three.

What does proton pumping produce across the inner mitochondrial membrane?

A steep electrochemical proton gradient.

What is the main function of ATP synthase in mitochondria?

To produce ATP using the energy stored in the electrochemical proton gradient.

What drives the transport of molecules across the inner mitochondrial membrane?

The electrochemical proton gradient.

What ratio does the rapid conversion of ADP to ATP maintain in cells?

A high ATP/ADP ratio.

Which activated carriers power ATP production during the citric acid cycle?

NADH and FADH2.

What molecule is produced when acetyl CoA is oxidized in the citric acid cycle?

CO2.

What are high-energy electrons from NADH passed along to?

The electron-transport chain in the inner membrane.

What is the net equation for the oxidation of NADH during oxidative phosphorylation?

2NADH + O2 + 2H+ → 2NAD+ + 2H2O.

What happens to protons when electrons are transferred to oxygen in mitochondria?

They are pumped across the inner mitochondrial membrane.

What is the role of ubiquinone and cytochrome c in the electron transport chain?

They serve as mobile carriers that ferry electrons between complexes.

What creates the proton-motive force in mitochondria?

The combination of membrane potential (∆V) and the pH gradient (∆pH).

How does ATP synthase function?

It converts the energy of protons flowing down their electrochemical gradient into chemical-bond energy in ATP.

What is the structure of ATP synthase?

It consists of a stationary head (F1 ATPase) and a rotating portion (F0).

What is an important characteristic of ATP synthase regarding its function?

It is a reversible coupling device.

How does the electrochemical proton gradient assist with importing pyruvate?

Pyruvate is transported into the matrix along with protons down their gradient.

What are the two processes by which ADP and ATP are exchanged across the membrane?

ADP is pumped into the matrix, while ATP is pumped out by an antiport process.

What does a higher concentration of protons in the intermembrane space indicate?

A slightly more acidic environment compared to the matrix.

What is the total ATP yield from the complete oxidation of one glucose molecule?

About 30 ATP.

What role do uncoupling agents play in mitochondrial function?

They make the inner mitochondrial membrane permeable to protons.

What happens in artificial lipid vesicles when bacteriorhodopsin is added?

It generates a proton gradient that drives ATP synthesis.

What is the result of the proton gradient being abolished in vesicles?

Elimination of light-induced ATP synthesis.

What was the first stage of evolution regarding ATP synthase?

The evolution of an ATPase that pumped protons out of the cell.

How are electrons transported through the electron transport chain?

They are transferred through three respiratory enzyme complexes.

What happens to protons during the operation of cytochrome c oxidase?

They are pumped across the membrane as electrons pass through.

What does electron transfer in the electron transport chain release?

Large amounts of energy.

What type of molecule do cytochrome c oxidase and other proton pumps utilize?

They use a conformational change to pump protons.

How do proton pumps operate regarding electron transport?

They couple proton pumping to the transport of electrons.

In which environment are the proton pumps located?

In the inner mitochondrial membrane.

What serves as the energy source for ATP synthesis in the mitochondria?

The proton-motive force generated by proton pumping.

What is formed when a tightly bound O2 molecule receives four electrons?

H2O.

What is the significance of cytochrome c oxidase's structure in relation to its function?

It is a dimer formed from multiple different protein subunits.

What process illustrates the efficiency of mitochondrial respiration?

Bioenergetics of ATP production from ADP and Pi.

What is the relationship between electron flow and proton pumping in mitochondria?

They are coupled; electron flow causes protons to be pumped out.

What is the proton gradient's effect on thermodynamic processes in mitochondria?

It drives various transport processes across the inner mitochondrial membrane.

How does protons' negative charge influence their transport into mitochondria?

Their movement is opposed by the negative membrane potential.

What does a high ΔpH indicate in the mitochondrial matrix?

A lower pH and higher proton concentration compared to the intermembrane space.

How are electron carriers oriented within the membrane?

They are embedded in a way that allows driving proton pumping as electrons are transferred.

What do artificial vesicles demonstrate about the requirement for ATP synthesis?

They need both bacteriorhodopsin and ATP synthase to produce ATP.

What do the experiments with bacteriorhodopsin confirm about proton gradients?

They can directly drive ATP production in conditions mimicked in the lab.

What evolutionary advantage did early cells with the ATP synthase system have?

They had a larger selective advantage over cells lacking this energy-generating mechanism.