Lecture 20: Anaerobic Fermentation Flashcards
How much energy is harvested from conversion of one glucose to 2 pyruvate molecules?
-2 ATP
-2NADH
Oxidative phosphorylation
- oxidation: electrons transferred from NADH and FADH2 to O2
-harvest ATP
-electron transfer coupled with transfer of protons across membrane to generate proton-motive force - Phosphorylation: ATP synthase produce ATP using proton motive force
Where does oxidative phosphorylation occur?
mitochondrial inner membranes
Energy yield of oxidative phosphorylation
-2.5 ATP per NADH
-1.5 ATP per FADH2
Energy yield of complete oxidation of glucose to CO2 and H20 by glycolysis, TCA cycle, and oxidative phosphorylation
32 ATP
Anaerobic Fermentation
-oxidative phosphorylation cannot occur without oxygen
-instead pyruvate must be REDUCED to lactate using 2 NADH
-cytosol
= 2 lactate + 2 ATP
ATP generation in red blood cells
-only by anaerobic fermentaition
-they have no mitochondria
Lactate
-decreases INTRAcellular pH which inhibits glycolysis
-too much may decrease BLOOD pH
lactic acidosis
-decrease of blood pH bc of excess lactate
-hypoxia, exercise, liver disease, ethanol, thiamin deficiency
Fate of Lactate
-transported with H+ to blood stream
-converted to pyruvate again where O2 supply is sufficient
lactate-H+ symporter
-transfers lactate and H+ from cytosol to blood stream
Ethanol Fermentation
-yeast converts pyruvate to ethanol when no oxygen
-ethanol later converted to acetate (used as energy source) when oxygen available
-bread and alcohol
Pyruvate decarboxylasse
-pyruvate to ethanol
-NADH to NAD+
Pyruvate dehydrogenase complex
-mitochondria
-catalyzes pyruvate to acetyl CoA
-IRREVERSIBLE
-INHIBITED by Aceytl CoA
-3 enzymes
Pyruvate dehydrigenase enzymes
E1: pyruvate dehydrogenase
E2: dihydrolipoyl TRANSacetylase
E3: hihydrolipoyl DEHYDROGENASE
Acetyl CoA
-produced from glucose, fatty acids, some amino acids (ketogenic)
-fuel TCA cycle
-material for fatty acid synthesis and ketogenesis
-CANNOT make glucose
Acetyl CoA produced by:
-pyruvate
-fatty acids
-ketogenic amino acids
Acetyl CoA produces
-CO2
-ketone bodies
-fatty acids
-cholesterol
Tricarboxylic Acid (TCA) cycle
-mitochondria
= 2 CO2
= 3 NADH, 1 FADH2, 1 GTP
-TOTAL concentration of intermediates does not change
TCA intermediates
-building blocks for gluconeogenesis and amino acid synthesis (neurotransmitters)
-decrease in concentrations slow down utilization of acetyl CoA and energy production
Citrate use
-fatty acid and sterol synthesis
a-Ketoglutarate use
-amino acid synthesis
-neurotransmitters
Succinyl CoA use
-heme synthesis
Malate use
gluconeogenesis
Oxaloacetate use
-amino acid synthesis
Anaplerotic reactions
-supply TCA intermediates
-when amino acids are not sufficient (growing cells), pyruvate is main source
Pyruvate carboxylase
-catalyzes most important anaplerotic reaction
-NEED for gluconeogenesis
-High in liver and nervous tissue
-pyruvate to oxaloacetate
Pyruvate carboxylase deficiency
-severe lactic acidosis
-infant death
-triheptanoin treatment
Triheptanoin
-treat pyruvate carboxylase deficiency
-triglycerid with fatty acid
-converted to succinyl CoA
Glycolysis and TCA summary
-in: glucose
-out: 6 CO2
-energy harvested: 2 ATP, 2 GTP, 10 NADH, 2 FADH2
