Bioenergetics Flashcards
How does pyruvate enter the mitochondria?
Through the Mitochondrial Pyruvate Carrier (MPC)
What catalyzes the conversion of pyruvate to AcetylCoA?
The Pyruvate Dehydrogenase Complex
What is the clinical importance of PDC?
A deficiency in phosphatase can lead to increased production of lactate instead of Acetyl-CoA. Leads to lactic acidosis.
What do the enzymes PDC and alpha-ketoglutarate dehydrogenase have in common?
They both require the same 5 coenzymes to function.
What are the two major anaplerotic reactions for the TCA cycle?
- Degradation of amino acids
2. Carboxylation of pyruvate
What is 2-Oxoglutaric aciduria?
Deficiency in alpha-ketoglutarate dehydrogenase. Leads to neurological problems and metabolic acidosis.
What are the oncometabolites of the TCA cycle?
Citrate and 2-hydroxyl glutarate
What are the two factors that constitutes the the proton-motive force (pmf)?
- pH gradient
2. Membrane potential
What is a potent inhibitor of complex V of the ETC?
Oligomycin
Describe the electron movement in the ETC when NADH is the electron donor.
Complex I —> CoQ —> Complex III —> Cyt-c —> Complex IV —> O2
Describe the electron movement in the ETC when FADH2 is the electron donor.
Complex II —> CoQ —> Complex III —> Cyt-c —> Complex IV —> O2
Which complexes of the ETC pump protons into the intermembrane space?
Complexes I, III, and IV
How and where does thermogenesis occur?
Occurs in brown adipose tissue. Uncoupling ATP synthase from ETC allows the energy from the proton gradient to be converted to heat via UCP-1 (thermogenin). UCP-1 is activated by long chain fatty acids binding.
What is DNP?
Uncoupling agent that prevents OxPhos from occuring by depleting the pmf in the form of heat production.
What is the purpose of the Malate-Aspartate shuttle and the Glycerophosphate shuttle?
To bring the NADH electrons from the cytoplasm into the mitochondrial matrix for use in the ETC.
What is the difference between the Malate-Asartate shuttle and the Glycerophosphate shuttle pathways?
The MA shuttle is reversible and can occur in either direction (such as in gluconeogenesis). The Glycerophosphate shuttle is not reversible, so it can occur under most conditions. The MA shuttle also generates NADH in the mito-matrix, where it enters the ETC at Complex 1. The Glycerophosphate shuttle generates FADH2, making it less energy efficient, and enters the ETC at CoQ.
Where does the Malate-Aspartate shuttle and Glycerophosphate shuttle occur?
The MA shuttle operates in the heart, liver, and kidneys. The Glycerophosphate shuttle occurs in the muscle and brain.
What are the products of the TCA cycle?
2 CO2, 1 FADH2, 1 GTP, and 3 NADH
What complex of the ETC do barbiturates inhibit?
Complex 1
What effect does high [Ca2+] have on PDC?
Increases its activity
What cofactor is used by PDC?
Thiamine pyrophosphate (Vitamin B1)
