glycolysis + gluconeogenesis Flashcards
what are the 3 irreversible steps of glycolysis/gluconeogenesis?
glucose -> g-6-p
fructose-6-phosphate -> fructose 1,6 bisphosphate
phosphoenolpyruvate -> pyruvate
what are the enzyme pairs for the irreversible reactions?
hexokinase + glucose 6 phosphatase
PFK1 + fructose 1,6 bisphosphatase
pyruvate kinase + (pyruvate carboxylase + PEP carboxykinase)
what determines the direction in which the pathway runs?
proportion of ATP molecules to AMP molecules (energy charge)
what does a high proportion of ATP to AMP mean for the reaction?
gluconeogenesis
since cell has enough ATP to meet needs
what does a high proportion of ATP to AMP mean for the reaction?
glycolysis
ATP is required
what are the key substrates of gluconeogenesis?
alanine, lactate, glycerol
what to include in description of metabolic pathways?
its substrates, finish products
notable steps/features
control points + regulatory enzymes
regulation including endocrine aspects
location: tissue and intracellular compartment
[abnormalities, metabolic diseases etc]
where does gluconeogenesis occur?
liver (+ limited capacity in kidney)
what tissues are invoked in gluconeogenesis? why?
muscle and adipose (Cori cycle and glucose-alanine cycle)
liver (alanine exported here) (where the pathway occurs)
what amino acids other than alanine are involved in gluconeogenesis?
glutamine: exported to kidney for processing there
what is the importance of different substrates in gluconeogenesis under differing metabolic conditions?
gluconeogenesis is active in starvation and exercise: both catabolic but with different profiles
the inter-tissue relationships of the substrates maintain glucose supply
glucagon and insulin regulate the pathway by regulating gluconeogenic enzyme transcription
mention diabetes as pathological state in which pathway is ‘inappropriately affected’
