Flashcards in pathways Deck (23)
Function: Provide blood glucose (liver). Provide glucose to produce energy for muscle contractions (muscle).
Substrates: Glycogen, Free phosphates
Products: free glucose and g-1-p or g-6-p
glycogenolysis (glycogen degradation)
Control Enzyme: glycogen synthase
Regulation: Insulin/Glucagon ratio and amount of glucose present (liver), epinephrine can also inhibit. Muscle insulin level (muscle).
Compartment: cytosol tissues: liver and muscles
Control: debrancher enzyme, glycogen phosphorylase
Reg: G phosphorylase, also epi has an effect. (Phosphorylation activates control enzyme.) In muscle, GNL is regulated via activation of glycogen phosphorylase by [AMP], [Ca2+],presence of epi C: Cytosol
Glycogenolysis (glycogen degradation)
Functions: To make NADPH (used for detoxification [ie. glutathione synthesis] and Reductive Biosynthesis [ie. fatty acid synthesis]) and Ribose 5 phosphate (nucleotide synthesis) .
Pentose Phosphate Pathway
Irreversible PPP Pathway.
Pathway synthesizes ribose 5-phosphate.
Non oxidative PPP
Functions: Produce energy and produce substrates for other anabolic pathways.
Substrates: Glucose (or G-6-P),ADP,NAD+
Product: ATP, pyruvate
2 primary control enzymes: Isocitrate dehydrogenase and a-Ketoglutarate dehydrogenase
Regulation: ATP/ADP ratio and the rate of ATP use
Compartment(s): Mitochondrial matrix Tissues: all except rbc
What happens to citrate in the TCA cycle?
Isomerized by aconitase to isocitrate
What are the electron carriers of the ETC?
NADH, FADH2, coenzyme Q, cytochrome C, O2
NADH & FADH2 are reducing or oxidizing agents?
strong reducing agents
Water-soluble electron carriers
electrons passed from succinate to FAD in TCA cycle, electrons are transferred from FADH2 to three Fe-S centers and then to Q, two protons are taken up to from QH2
Complex II:succinate dehydrogenase
FMN (riboflavin) accepts electrons and protons from NADH+H to become FMNH2, FMNH2 contains an iron/sulphur center which takes two hydrogen and transfers them to coenzyme Q = QH2 (4 protons transferred into intermembrane space of mito)
Complex I:NADH Dehydrogenase action
Q bind CytoB and heme accepts e-, e- transferred to CytoC1, CytoC1 (membrane bound) transfers e- to CytoC (water soluble/mobile) which can diffuses and donate it's electrons to complex IV, 4 protons pumped
Complex III: cytochrome C oxidoreductase
iron atoms of the heme groups in the cytochromes and copper atoms are oxidized and reduced as electrons flow from cyto C to O2 to make water, 2 protons pumped
Complex IV: cytochrome oxidase
Where does superoxide USUALLY come from?
leaks from complex I
What type of metabolic pathway is Gluconeogenesis?
* generates glucose from non carb carbon substrates
What type of metabolic pathway is Glycogenesis?
* generates glycogen from glucose molecules
What type of metabolic pathway is Glycolysis?
* converts glucose to pyruvate
What type of metabolic pathway is Citric acid cycle?
* converts CHO, fat, protein into CO2 and water
This pathway synthesizes ribose 5-phosphate.
PPP Non oxidative pathway