Chapter 9.3.2 (Exam 2) ETC

Question 1

What is the ETC dependent on?

Answer 1

The impermeability of the inner mitochondrial membrane to H+ ions

Question 2

What happens if the inner mitochondrial membrane becomes permeable to protons?

Answer 2

Electron transport and chemiosmosis become uncoupled because the proton-motive force is no longer possible

Energy crosses the membrane and is released as heat rather than forming bonds for ATP

Question 3

What is one example of the inner mitochondrial membrane becoming permeable to protons?

Answer 3

In brown fat cells, a protein called UCP1 inserts into the mitochondrial membrane and makes it permeable to protons

Question 4

ATP synthase is the same in all living organisms. Describe its structure.

Answer 4

It is a molecular motor with two parts:

F0 unit

F1 unit

Question 5

Describe the F0 unit of ATP synthase.

Answer 5

a transmembrane H+ channel

Question 6

Describe the F1 unit of ATP synthase.

Answer 6

Projects into the mitochondrial matrix

Rotates to expose active sites for ATP synthesis

Question 7

How does ATP synthase function?

Answer 7

When H+ diffuses through the F0 channel, the potential energy is converted to kinetic energy, causing the central polypeptide to rotate

The energy is transmitted to the catalytic subunits of F1, resulting in ATP synthesis

Question 8

How do many bacteria respirate efficiently in the absence or scarcity of oxygen?

Answer 8

Anaerobic respiration:

Many bacteria and archaea use alternate electron acceptors such as SO4-2, Fe3+, and CO2