Lecture 21b

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What is the main purpose of the malate-aspartate shuttle system?

To generate 2.5 ATP per pair of electrons passed from NADH to oxygen
To transport electrons from NADH in the cytoplasm to complex I in the mitochondria
To indirectly convey cytosolic NADH into mitochondria for oxidation (correct)
To directly transport NADH from the cytoplasm into the mitochondrial matrix

Why is the malate-aspartate shuttle considered the most active shuttle mechanism?

It can generate 2.5 ATP per pair of electrons passed from NADH to oxygen
It can transport electrons from NADH in the cytoplasm to complex I in the mitochondria
It depends on two transporters that allow for the exchange of malate and aspartate across the inner mitochondrial membrane (correct)
It can directly transport NADH from the cytoplasm into the mitochondrial matrix

How does the malate-aspartate shuttle system indirectly convey cytosolic NADH into the mitochondrial matrix?

By using the exchange of malate and aspartate across the inner membrane to shuttle the electrons (correct)
By transferring electrons from NADH in the cytoplasm to complex I in the mitochondria
By directly transporting NADH across the inner mitochondrial membrane
By generating 2.5 ATP per pair of electrons passed from NADH to oxygen

What is the role of complex I in the malate-aspartate shuttle system?

Complex I receives the electrons shuttled from the cytoplasm to the matrix via the malate-aspartate system (A) Signup and view all the answers

What is the purpose of shuttling the electrons from cytosolic NADH into the mitochondrial matrix?

To allow NADH to be reoxidized to NAD+ in the mitochondria (C) Signup and view all the answers

What is the composition of the F1 subunit of the ATP synthase complex?

33 (D) Signup and view all the answers

What is the role of the two b subunits (b2) in the Fo subunit of the ATP synthase complex?

They associate firmly with the and subunits of F1, holding them fixed relative to the membrane. (B) Signup and view all the answers

What is the role of the $eta$ subunits in the ATP synthase complex?

It is part of the mechanism that couples the rotation of the cylinder and $eta$ shaft to the synthesis of ATP. (C) Signup and view all the answers

What is the primary driving force for ATP synthesis in mitochondria?

The proton-motive force generated by the electron transport chain (D) Signup and view all the answers

Which of the following is NOT a component of the proton-motive force?

The difference in electron concentration across the inner mitochondrial membrane (A) Signup and view all the answers

What is the correct formula for calculating the free energy (ΔG) of the proton-motive force?

ΔG = RT ln (C2/C1) + ZFΔψ (C) Signup and view all the answers

In the chemiosmotic model for ATP synthesis, what is the role of the electron transport chain?

To generate a proton gradient across the inner mitochondrial membrane (D) Signup and view all the answers

Which of the following statements about the proton-motive force is correct?

It represents the temporary storage of energy from electron transfer reactions (D) Signup and view all the answers

In the formula for calculating the free energy (ΔG) of the proton-motive force, what does the term 'ZFΔψ' represent?

The electrical gradient component of the proton-motive force (C) Signup and view all the answers

What is the primary mechanism that regulates oxidative phosphorylation?

Availability of NADH and ADP/Pi (B) Signup and view all the answers

What is the function of the F-type ATPases?

They catalyze the hydrolysis of ATP to drive proton pumping (D) Signup and view all the answers

What is the role of the inhibitor of F1 (IF1) protein?

It prevents the hydrolysis of ATP by ATP synthase during hypoxia (C) Signup and view all the answers

What happens when oxidative phosphorylation is inhibited?

NADH accumulates, leading to feedback inhibition of glycolysis (A) Signup and view all the answers

Under what conditions is the IF1 protein active?

At lower pH levels encountered during hypoxia (B) Signup and view all the answers

What is the purpose of the coordinated regulation of ATP-producing pathways?

To ensure efficient energy production (A) Signup and view all the answers

What is the primary role of the adenine nucleotide translocase in the mitochondrial inner membrane?

It transports ADP into the matrix and ATP out of the matrix in an antiport mechanism. (B) Signup and view all the answers

How does the proton-motive force contribute to ATP synthesis and substrate transport in the mitochondrial matrix?

It provides the energy for ATP synthesis and facilitates the transport of ADP and Pi into the matrix. (B) Signup and view all the answers

What is the role of the phosphate translocase in the mitochondrial inner membrane?

It transports H2PO4- and H+ into the matrix in a symport mechanism. (A) Signup and view all the answers

What is the significance of the conformational change in the F1 beta subunits of the ATP synthase complex?

It causes a cooperative change that prevents ATP release until ADP and Pi are bound. (B) Signup and view all the answers

What is the net charge movement across the mitochondrial inner membrane during the transport of ADP and Pi into the matrix?

One negative charge is moved out of the matrix. (C) Signup and view all the answers

What is the driving force for the transport of H2PO4- into the mitochondrial matrix by the phosphate translocase?

The relatively low proton concentration in the matrix. (D) Signup and view all the answers