ATP Formation and Oxidative Phosphorylation

Flashcards on ATP formation, oxidative phosphorylation, and the electron transport chain.

What is the chemical structure of ATP?

A nucleoside triphosphate containing adenine, ribose, and three phosphate groups.

What does ATP do for you?

It supplies energy and is the energy currency of the cell.

What cycle is responsible for continuously consuming and regenerating ATP?

ADP-ATP Cycle

What process produces most of the ATP?

Oxidative phosphorylation

Where is the electron transport chain located?

Inner mitochondrial membrane

What is the primary function of the electron transport chain?

Transport of electrons from reducing equivalents (NADH and FADH) to O2 to produce H2O.

What are enzyme complexes in the electron transport chain composed of?

Integral membrane proteins with groups capable of accepting and donating electrons.

What is the permeability of the outer mitochondrial membrane?

Highly permeable

What is the permeability of the inner mitochondrial membrane?

Highly impermeable

What are the sources of reduced coenzymes?

Glycolysis, Fatty Acid Oxidation, Amino Acid Oxidation, Citric Acid Cycle

Define oxidation.

Addition of oxygen or removal of hydrogen/electron.

Define reduction.

Addition of an electron or hydrogen or removal of oxygen.

What is the relationship between oxidation and reduction reactions?

They are always coupled

What molecules drive the pumping of protons out of the mitochondrial matrix?

NADH and FADH2

What is the primary function of Complex I in the electron transport chain?

It catalyzes oxidation of NADH+H, with reduction of coenzyme Q.

What components make up Complex I?

NADH dehydrogenase, FMN, and Fe-S centers

What molecule do electrons eventually transferred to via Complex I?

Coenzyme Q

What is the main function of Complex II?

It catalyzes oxidation of FADH2, with reduction of coenzyme Q.

What components make up Complex II?

Succinate Dehydrogenase, FAD, and Fe-S centers

What is the role of Coenzyme Q?

It acts as a mobile component of the respiratory chain.

What is the function of Complex III?

It accepts electrons from reduced Co Q and electrons flow through cytochrome b,c1.

How are electrons carried through Complex III?

Heme iron oscillates between Fe+++ and Fe++

What is the role of cytochrome b,c1 in Complex III

Electrons are carried on Heme iron which oscillates between Fe+++ and Fe++

Which complex contains cytochrome a and a3?

Complex IV

Which complexes act as proton pumps?

Complexes I, III, and IV

What enzyme is scattered on the surface of the inner mitochondrial membrane?

ATP-synthase (complex V)

Define the P:O ratio.

No. of ATP molecules produced / No. of Oxygen atoms consumed

What is the P:O ratio if starting from NADH?

2.5:1

What is the P:O ratio if starting from FADH2?

1.5:1

Name inhibitors of Complex I.

Barbiturates (Amytal) and the insecticide rotenone.

Name an inhibitor of Complex III.

The antibiotic: antimycin A.

Name inhibitors of Complex IV.

H2S, CO and cyanide.

Name an inhibitor of ATP Synthase (Complex V).

Oligomycin.

What happens if Complex I is inhibited?

It will allow the mitochondria to use succinate.

How do uncouplers abolish the coupling between oxidation and phosphorylation?

Increasing the permeability of the IMM to H+.

What is the effect of uncouplers on ATP formation and oxidation?

ATP formation stops while oxidation proceeds.

Name examples of uncouplers.

2,4 dinitrophenol, Bilirubin, Thyroxine, and Thermogenine

What is the function of Thermogenine?

It allows protons to pass the mitochondrial matrix without passing F0-F1 complex, releasing energy as heat.

What is the effect of adding dinitrophenol on O2 utilization?

Complete utilization of oxygen.

What is the effect on O2 utilization with the addition of amytal or rotenone to malate?

Inhibition of O2 utilization