Coupling and uncoupling of Oxidative phosphorylation

Question 1

What is uncoupling of oxidative phosphorylation

Answer 1

Uncoupling of oxidative phosphorylation occurs when protons are returned to the matrix by other means then the ATP synthase.

Chemical uncouplers or endogenous uncoupling proteins allow protons to bypass ATP synthase and return to the matrix by other routes.

Question 2

What is uncoupling of oxidative phosphorylation

Answer 2

Uncoupling of oxidative phosphorylation occurs when protons are returned to the matrix by other means then the ATP synthase.

Chemical uncouplers or endogenous uncoupling proteins allow protons to bypass ATP synthase and return to the matrix by other routes.

Question 3

What is chemiosmotic coupling

Answer 3

The general mechanism for ATP generation by oxidative phosphorylation is chemiosmotic coupling

Question 4

Explain thermogenin (uncoupling protein)

Answer 4

-Expressed in brown adipose tissue (BAT= adipose stores energy, so brown adipose burns this energy for heat production)
-Found in the inner mitochondrial membrane.
-Allows the production of heat through proton dissipation (Protons go back through UCP1 instead of ATP synthase to dissipate the proton energy in heat )
-Plays a role in non-shivering thermogenesis:
Regulation of heat of infants
Mammals waking up after hibernation

Question 5

Thermogenin in infants

Answer 5

Heat is generated through nonshivering thermogenesis in kids until they turn about 1 year old

Question 6

Explain squirrel hibernation in terms of UCP1 (how it could potentially relate to space travel)

Answer 6

UCP1 level is high in the brain and the spinal cord as shown in figure A when they are in hibernation. So it keeps the brain in some state where its not in hibernation and somewhat awake. The increase in temperature will signal them through UCP1 to wake up.

When they come out of hibernation it takes them a few hours for them to function. Vs squirrels they can go wake up, gather food, and then go back into hibernation, they are ready to function unlike other animals because they contain UCP-1 in the brain. Use brown fat adipose tissue usage to wake up and warm up the body after hibernation, then when in hibernation they use less brown adipose tissue

**maybe inject UCP1 in human brain to hibernate for space travel

Question 7

2,4-dinitrophenol (uncoupling mechanism)

Answer 7

-Uncoupling agent or uncoupler
-Transport of protons across the membrane (DNP acquires a proton, crosses membrane to mitochondrial membrane to drop off proton, then moves back across membrane (this mechanism also produces heat)
-This transport generates heat (same as UCP1).

Question 8

What was DNP 2,4-dinitrophenol used for in the 1930’s

Answer 8

DNP was used in the 1930s as a weight loss supplement, unfortunately, it had major side effects; causing blindness (development of cataract), hyperthermia and even death.

This is just burning energy to lose weight by using DNP, not producing ATP (so body doesn’t get energy) so body has to burn fats and carbohydrates to produces energy