Glucose metabolism & cellular respiration Flashcards
(36 cards)
in the presence of oxygen, glycolysis is the first step of cellular respiration. T or F.
T
Glycolysis is also known as?
The Embden-Meyerhof-Parnas (EMP) pathway
note: has 10 steps
rate limiting step/ committed step of glycolysis?
Reaction 3: phosphorylation
PFK-1 catalyses the reaction- fructose-6-phosphate to fructose 1,6-biphosphate
what is glycolysis (simple)?
1 glucose → 2 pyruvate + 2 ATP + 2 NADH
(takes place in the cytoplasm in eukaryotes)
what regulates glycolysis?
3 irreversible steps
- step 1: hexokinase (phosphorylation)
- step 3: PFK 1 (phosphorylation)
- step 10: pyruvate kinase (substrate-level phosphorylation)
what are the 3 steps of cellular respiration?
- glycolysis (in cytosol)/anaerobic
- citric acid cycle (in mitochondrial matrix)/aerobic
- electron transport chain (inner mitochondrial matrix)/aerobic
if glycogen stores are depleted then liver cells will synthesise glucose by what?
gluconeogenesis
note: liver can replenish blood glucose levels through gluconeogenesis
Gluconeogensis is what?
the synthesis of glucose from non-carbohydrate precursors
what is the importance of glycogen?
maintain blood glucose levels
what are the major sites that store glycogen?
- liver (10% of weight)
- skeletal muscle (2%)
note: glycogen is stored in cytosolic granules in vertebraes
whats the key molecule in glycogen synthesis?
UDP-glucose (glucose 1-phosphate + UTP)
What is the pentose phosphate pathway?
- alternative route for the metabolism of glucose (it’s a shunt) which takes place in the cytosol
- glucose 6-phosphate is metabolised and net result is 2 NADPH and 1 ribose-5-phosphate
what happens when the citric acid cycle is deficient in oxaloacetate or any other intermediates?
pyruvate is carboxylated to produce more oxaloacetate (anaplerotic reaction)
what happens in the krebs cycle? simple
acetyl groups are fed into the citric acid cycle, which enzymatically oxidizes them to CO2. The energy released is conserved in the reduced electron carriers NADH and FADH2
what happens in the electron transport chain? simple
reduced co-factors are oxidized (giving up protons (H+) and electrons). The electrons are transferred along a chain of electron-carrying molecules (electron transport chain) to O2, which they reduce to form H2O
note: oxidative phosphorylation
Most of the electrons entering the mitochondrial respiratory chain arise from the action of dehydrogenases that collect electrons from the oxidative reactions of ?
- the pyruvate dehydrogenase complex,
- the citric acid cycle,
- the β-Oxidation pathway,
- oxidative steps of amino acid catabolism
what are the main functions of the ETC?
- regenerates electron carriers: The oxidized forms of these electron carriers (NAD+ & FAD) are reused in glycolysis and the citric acid cycle
- builds a proton gradient: across the inner mitochondrial membrane; this gradient represents a stored form of energy which is used to make ATP.
whats chemiosmosis?
process in which energy from a proton gradient is used to make ATP
which process produces most of the ATP made in cells?
oxidative phosphorylation
concentrations of ATP and ADP control the rates of?
- electron transfer
- oxidative phosphorylation
- TCA cycle
- pyruvate oxidation
- glycolysis
note: high levels of ATP will decrease everything while low levels of ATP will increase everything
ATP is an allosteric inhibitor of which enzymes?
phosphofructokinase-1 and pyruvate dehydrogenase
what are the four complexes of the ETC?
- NADH dehydrogenase
- succinate dehydrogenase
- cytochrome c reductase
- cytochrome oxidase
how many electrons are needed to reduce each molecule of O2?
4 baby!!!
What is the cori cycle?
the process where glucose is converted to lactate (glycolysis) in the active muscle then in the liver this lactate is re-converted to glucose (glucogenesis).
