ETC Flashcards
What is bioenergetics?
Bioenergetics is the study of energy flow and energy transformations in biological systems.
What are high energy compounds?
High energy compounds are chemical compounds that store energy, which is released during hydrolysis of high energy bonds.
How is energy released from high energy compounds?
Energy is released when high energy bonds in compounds are hydrolyzed, resulting in products that are in a lower energy state.
What types of bonds are considered high energy bonds?
High energy bonds include phosphoanhydride, enolphosphate, acylphosphate, guanidine phosphate, and thioester bonds.
What is the phosphoanhydride bond?
A phosphoanhydride bond is formed between two molecules of phosphoric acid, liberating approximately 30.5 KJ/mol upon hydrolysis.
Example: ATP, di- and triphosphates of purine and pyrimidine nucleosides.
What is the enolphosphate bond?
An enolphosphate bond is formed when a phosphate group is attached to a hydroxyl group on a carbon with a double bond, liberating 61 KJ/mol upon hydrolysis.
Example: Phosphoenolpyruvate.
What is the acylphosphate bond?
An acylphosphate bond is formed by the reaction of a carboxylic acid with a phosphate group, liberating approximately 49 KJ/mol of energy upon hydrolysis.
Example: 1,3-bisphosphoglycerate.
What is the guanidine phosphate bond?
A guanidine phosphate bond is formed when a phosphate group is attached to a guanidine group, with a hydrolysis energy of 43 KJ/mol.
Example: Phosphocreatine.
What is the thioester bond?
A thioester bond is formed between a carboxylic acid and a sulfhydryl group, liberating 41 KJ/mol upon hydrolysis.
Example: Acetyl-CoA.
What is ATP?
ATP (adenosine triphosphate) is a nucleoside triphosphate containing adenine, ribose, and three phosphate groups.
What is the significance of ATP in cellular processes?
ATP plays a central role in transferring free energy from exergonic to endergonic processes and acts as a phosphate donor.
What are coupled reactions?
Coupled reactions occur when an energetically unfavorable reaction is linked to an energetically favorable reaction, often through ATP hydrolysis.
What is biological oxidation?
Biological oxidation is the transfer of electrons from reduced coenzymes (NADH and FADH2) to oxygen, releasing energy that is trapped as ATP.
What is oxidative phosphorylation?
Oxidative phosphorylation is the process by which ATP is synthesized as electrons pass from NADH and FADH2 to oxygen.
Where does electron transport occur?
Electron transport occurs on the inner membrane of the mitochondrion.
What are the components of the electron transport chain (ETC)?
The components include coenzyme Q (ubiquinone), cytochromes, and iron-sulfur proteins.
What is the chemiosmotic theory?
The chemiosmotic theory states that as electrons are transported, H+ ions are pumped out of the mitochondrion, creating a proton gradient that drives ATP synthesis.
What is the stoichiometry of ATP synthesis?
Synthesizing one ATP requires the re-entry of 4 H+ ions, with different ATP equivalents produced from NADH and FADH2 reoxidation.
What are electron transport inhibitors?
Electron transport inhibitors are compounds that inhibit electron transport and oxidative phosphorylation, such as carbon monoxide and cyanide.
What is oligomycin?
Oligomycin is an inhibitor of ATP synthase that indirectly inhibits electron transport by steepening the proton gradient.
What are site-specific inhibitors of the ETC?
Site-specific inhibitors target specific complexes in the ETC, such as rotenone for Complex I and cyanide for Complex IV.
What are uncouplers of oxidative phosphorylation?
Uncouplers collapse the chemiosmotic gradient, dissipating protons across the inner mitochondrial membrane and releasing energy as heat.
Example: Dinitrophenol (DNP).
What is thermogenin?
Thermogenin is a natural uncoupling protein found in brown adipose tissue that decreases the proton gradient and releases energy as heat.
What is the P/O ratio?
The P/O ratio indicates the number of moles of inorganic phosphate taken up per oxygen atom consumed, with values of 2.5 for NAD-linked substrates and 1.5 for FAD-linked substrates.
What are shuttle systems in cellular respiration?
Shuttle systems allow NADH and NADH + H+ to transfer reducing equivalents across the inner mitochondrial membrane, facilitating ATP production.
