proton motor force

Question 1

Where does ATP synthesis occur?

Answer 1

Inner mitochondrial membrane

This is the site where ATP is generated during oxidative phosphorylation.

Question 2

What drives the synthesis of ATP?

Answer 2

Proton motor force

The proton motor force is established by the flow of protons across the mitochondrial membrane.

Question 3

What enzyme catalyzes the formation of ATP from ADP and inorganic phosphate?

Answer 3

ATP synthase

ATP synthase is located in the inner mitochondrial membrane and consists of two parts.

Question 4

What are the two parts of ATP synthase?

Answer 4

• Fo: Protons flow back into the matrix through this pore
• F1: Spherical head on which phosphorylation of ADP occurs

These components work together to synthesize ATP.

Question 5

What is the role of cristae in mitochondria?

Answer 5

Caused by dimerization of 2 ATP synthase molecules

Cristae increase the surface area for ATP synthesis.

Question 6

How much ATP is produced per NADH?

Answer 6

2.5 ATP

NADH is a key electron carrier in the electron transport chain.

Question 7

How much ATP is produced per FADH2?

Answer 7

1.5 ATP

FADH2 enters the electron transport chain at a different point than NADH.

Question 8

How is ATP produced in mitochondria moved to the cytosol?

Answer 8

ATP-ADP Translocase

This transporter exchanges ATP produced in the mitochondria for ADP from the cytosol.

Question 9

What are the two shuttles that transport NADH into mitochondria?

Answer 9

• Malate-aspartate shuttle (2.5 ATP/NADH) → liver/heart
• Glycerol 3-phosphate shuttle (1.5 ATP/NADH) → muscle

These shuttles facilitate the movement of NADH to support oxidative phosphorylation.

Question 10

What is non-shivering thermogenesis?

Answer 10

Electron transport uncoupled from ATP synthesis, heat gets generated instead of ATP

This process allows for heat production without ATP generation.

Question 11

What happens as protons pass through the pore in ATP synthase?

Answer 11

The ring of epsilon subunits (from Fo) rotates

This rotation is crucial for ATP synthesis.

Question 12

What are the three states of the beta subunits in ATP synthase?

Answer 12

• L (loose): binds ADP and P
• T (tight): ATP is synthesized
• O (open): low affinity for ATP, released

These states facilitate the binding and release of ATP during synthesis.

Question 13

Do beta subunits in ATP synthase rotate?

Answer 13

No, beta subunits do not rotate

The y subunit spins, causing conformational changes in the beta subunits.