Glycolysis, the catabolism of glucose Flashcards
more than half of all organic carbon is in two polysaccharides, what are they
Starch and cellulose
Glucose is our primary energy source, what is it oxidised to
CO2 and H2O
What cell types require glucose as an energy source
erythrocytes
retina
renal medulla
brain
what are the intracellular stages of metabolism
stage 2, Acetyl-CoA production
stage 3, Acetyl CoA oxidation
Electron transfer and oxidative phosphorylation
how does glucose transport into cells
Na+/glucose symporters
Outside the cell high Na+ concentration and low K+ concentration
inside the cell low Na+ and high K+ concentration
explain glucose binding
1) glucose binding to the outside causes conformation change so that the binding site faces inwards
2) Glucose can be released in the inside
3) Conformational change regenerates the binding site on the outside
what is the overall glycolysis reaction
glucose + 2ADP + 2Pi +2NAD+—-> 2 pyruvate + 2ATP + 2H2O + 2NADH + 2H+
what is the overall glycolysis pathway
glucose (2ATP -> 2ADP) –> fructose-1,6- bisphosphate –> 2 triose phosphates (4 ADP –> 4 ATP) (2NAD+ –> 2NADH + 2 H+) —> 2 pyruvate
3 stages of glycolysis simplified
stage 1: glucose is trapped and destabilized
stage 2: two inconvertible three-carbon molecules are formed
stage 3: generation of ATP
what are 2 major cellular needs
production of ATP
provision of building blocks for synthetic reactions
what is the function of hexokinase
catalyzes the phosphorylation of glucose, rate limiting first step
glucose + ATP –> glucose-6-phosphate + ADP + H+
what is the function of phosphofructokinase
fructose-6-phosphate + ATP —> fructose 1,6-bisphosphate + ADP + H+
pyruvate kinase
phospoenolpyruvate + ADP + H+ —> pyruvate + ATP
what are the positive and negative modulators
negative modulators:
ATP
citrate
H+ - prevents excessive formation of lactic acid
positive modulators:
AMP
fructose 2,6 -bisphosphate
