Glucose Oxidation & Shuttles Flashcards
Mention the three principal phases of cellular respiration
- Oxidation of fuels
- Conversion of energy from fuel oxidation into high energy phosphate bond
- Utilization of high phosphate bond energy
The convergent product of oxidation of most fuels
Acetyl CoA
Complete oxidation of acetyl CoA occurs in …… and produces ….&….
Tricarboxylic acid cycle
NADH & FADH2
Define the electron transport chain
A process in which electrons are transferred from NADH and FADH2 to O2.
Enumerate processes requiring ATP
Muscle contraction, maintaing intracellular Na concentration, anabolic pathways & detoxification.
The ETC occurs in ….., while …..&….. occur in mitochondrial matrix.
Inner mitochondrial membrane
TCA & oxidation of fatty acids
Compare aerobic & anaerobic glycolysis fate of NADH & pyruvate
A: NADH reoxidized in ETC, pyruvate completely oxidized in TCA cycle.
An: NADH reoxidised by conversion of pyruvate to lactate.
Examples of anaerobic glycolysis
In RBCs , kidney medulla & exercising muscle
NADH is indirectly transferred to inside the mitochondria by …..
Shuttle mechanism (malatae aspartate shuttle & glycerophosphate shuttle)
Describe the steps of malate shuttle
Electrons from NADH convert oxaloacetate to malate by cytosolic malate dehydrogenase.
Malate crosses the inner mitochondrial membrane by special translocase.
Electrons of malate reform NADH, and oxaloacetate is reformed (by mitochondrial malate dehydrogenase) which is converted by AST to aspartate which is transported out by aspartate/glutamate exchange translocase.
The major shuttle is
Glycerol phosphate shuttle
Describe the mechanism of glycerol phosphate shuttle
Cytoplasmic Glycerol 3-phosphate dehydrogenase uses electrons from NADH to convert DHAP to GAP which diffuses to mitochondria then its electrons are donated to give FADH2 (gives 2 ATP in ETC)
PDC reaction is one of
Oxidative decarboxylation
Mention the 3 enzymes of PDC
Pyruvate dehydrogenase, dihydrolipoyl transacetylase & dihdrolipoyl dehydrogenase
Mention the coenzymes of PDC
Thiamin pyrophosphate, lipoic acid, CoASH, FAD and NAD+.
…….. inhibits pyruvate dehydrogenase while ….. activates it. (Covalent modification)
Phosphorylation
Dephosphorylation
PDC kinase is inhibited by ….&…., while it is activated by ….&…… .
ADP & pyruvate
Acetyl CoA & NADH
Mention the regulation of PDC phosphatase in the heart
Calcium is required for its activity
Increased mitochondrial Ca++ during rapid contraction activates the phosphatase, thereby increasing the amount of active PDC.
Describe the hormonal regulation of PDC
Insulin favor the active, dephosphorylated form, while glucagon favors the phosphorylated, inactive form.
Mention the fates of pyruvate
Converted to: alanine, lactate, acetyl CoA, oxaloacetate.
…..&…. Are irreversible enzyme acting on pyruvate, while ….&…. Are reversible
Pyruvate carboxylase, PDC
LDH, transamination
Dietary deficiency of thiamin pyrophosphate results in the following diseases:
Beriberi
Wernicke-Korsakoff syndrome
Alcohol addiction result in deficiency of ….
Thiamin pyrophosphate
…. Inhibits lipoic acid containing enzymes such as …..&….. .
Arsenite
PDC & alpha-ketoglutarate dehydrogenase complex
Abnormalities in the PDC lead to accumulation of ….
Lactate
