ETC Flashcards
standard free energy of hydrolysis of ATP
-7300 cal/mol
How many electron pairs generated from one molecule of glucose?
12: 2 from glycolysis, 2 from PDH, and 8 from TCA
electron pairs are transferred to _
10 NADH and 2 FADH2 molecules to be transferred to O2 in ETC
access to glycolytically produced cytosolic NADH
to get into the inner mitochondria membrane, NADH from glycolysis must be transported through glycerophosphate shuttle and malate/aspartate shuttle
glycerophosphate shuttle
glycerol-3-phosphate dehydrogenase oxidizes NADH to form glycerol-3-phosphate which is then oxidized by flavoprotein dehydrogenase to form FADH2 which supplies electrons for ETC
Where is glycerophosphate shuttle (NADH shuttle) located?
in the brain and skeletal muscle
malate/aspartate shuttle
NADH oxidized by malate dehydrogenase, converting oxaloacetate to malate –> malate taken into matrix in exchange for alpha-KG –> malate reoxidized to oxaloacetate, regenerating NADH (by malate dehydrogenase)
Where is malate/aspartate shuttle located?
heart, liver, and kidneys
How many ATP does glycerophosphate shuttle yield?
2 ATP
How many ATP does malate/aspartate shuttle yield?
3 ATP
complex I generates
4 H+
complex III generates
4 H+
complex IV generates
2 H+
complex I
NADH dehydrogenase (NADH-coenzyme Q reductase)
NADH dehydrogenase
passes electrons from NADH to coenzyme Q
NADH can donate _ electrons
two
cytochromes can only accept _ electrons
one
complex II
succinate dehydrogenase
succinate dehydrogenase
FADH2 to FAD and passes electrons to coenzyme Q
coenzyme Q (ubiquinone)
accepts protons from complex I and complex II and transports them to complex III
complex III
cytochrome bc1
complex IV
cytochrome c oxidase
cytochromes
contain a heme group to carry electrons (electron binding converts Fe+3 to Fe+2)
mechanism of ATP synthesis
proton motive force across the mitochondrial membrane is harnessed in the synthesis of ATP by proton-translocating ATP synthase (F0 and F1)
F0
water-insoluble transmembrane protein composed of 8 types of subunits that contain a proton translocation channel
F1
water-insoluble peripheral membrane protein composed of 5 types of subunits; ATP-synthesizing portion of enzyme
How many protons must pass for each ATP synthesized?
3 protons
F1-F0 ATPase
gamma subunit within the F1 protein functions as a molecular cam shaft in linking the proton-motive force-driven rotational motor to the conformational changes in catalytic sites of F1
DNP and FCCP
uncouple processes because they render the IMM permeable to protons; allow electron transport to proceed even when ATP synthesis is inhibited
defects in oxidative phosphorylation are due to _
mutations in mitochondrial DNA, affecting tissues with the greatest ATP requirements (CNS, liver, kidney, skeletal & cardiac muscle)
diseases associated with mtDNA alterations
Leber’s, Leigh, myoclonic epilepsy with ragged red fibers (MERRF), and NARP syndrome
neurodegenerative diseases associated with oxidative damage to mitochondria
Parkinson’s, Alzheimer’s, and amyotrophic lateral sclerosis
Leber’s hereditary optic neuropathy (LHON)
due to mtDNA mutation causing amino acid change in NADH dehydrogenase –> leads to bilateral loss of central vision as a result of neuroretinal degeneration
Leigh disease (subacute necrotizing encephalopathy)
mutation in 1 of more than 75 different nuclear or mitochondrial DNA genes involved in energy production in mitochondria –> leads to progressive swallowing problems, poor weight gain, hypotonia, weakness, ataxia (death within 3 years)
