Module 1: Carbohydrates III Part 2

Question 1

Proton motive force - electrochemical gradient

Answer 1

• The ETC causes translocation of H+ from the matrix side to the cytosolic side of inner membrane
• Results in a pH difference across the inner membrane
• Delta pH = pH matrix – pH cytosolic side = positive number = +1 pH units
• Causes an electrical potential difference (Delta Psi) across the inner membrane
• Delta Psi = Psi matrix – Psi cytosolic side = negative number = -0.18 volts
• This is because matrix side has a more negative charge than the cytosolic side

Question 2

A chemical reaction that adds free energy to a molecule is

Answer 2

-Reduction

Question 3

Removing free energy from a molecule is called

Answer 3

-Oxidation

Question 4

The transfer of energy is called a ____ _____ because…

Answer 4

• Redox reaction

- Because one or more molecules is reduced (gains energy) while one or more is oxidized (loses energy)

Question 5

How do e-‘s flow from one redox couple to the other?

Answer 5

The reduced form of the redox couple of more negative reduction potential will donate e-‘s to the oxidized form of the redox couple of more positive reduction potential

Question 6

What is ROS?

Answer 6

• Reactive oxygen species

- AKA free radicals

Question 7

Which ETC complexes generate ROS? When do they produce them?

Answer 7

• Complex I ROS from the FMN site, facing in.

- Complex III ROS from semiquinone, on both sides of the membrane

Question 8

Reasons for H+ Leak

Answer 8

• Thermogenesis
• Metabolic “Idling” -> to continue the flow of e- (runs slowly)
• Metabolic “Switch”
• Regulation of Free Radicals -> free radicals increase w/ inactivity due to buildup of H+ gradient