Gluconeogenesis Flashcards
(26 cards)
what happens if glucose level in our body is low
examples of tissues that require glucose
brain
RBC
kidney medulla
lens and cornea
testes
exercising muscle
which tissues synthesise glucose
liver (90%) and kidney (10%)
what are precursors of glucose
lactate
pyruvate
glycerol
glucogenic amino acids - alanine
what are sources of precursors of glucose
diet
liver/muscle glycogen store
what results after glycogen reserves are exhausted in starvation
breakdown of muscle proteins to glucogenic amino acids
around 30% in the form of alanine
where does oxaloacetate synthesis for gluconeogenesis exclusively occur
mitochondrion
in which type of cells must oxaloacetate be transported through one of two routes to the cytosol
cytosolic-exclusive PEPCK cells
cells which contain PEPCK in the cytosol only and not in the mitochondria also
what are the two routes though which oxaloacetate can cross the mitochondrial membrane
conversion to either malate or aspartate
transport via transporter protein
conversion back to oxaloacetate
which enzyme converts between oxaloacetate and malate
malate dehydrogenase
which enzyme converts between aspartate and oxaloacetate
aspartate aminotransferase
what type of acids cannot be used for gluconeogenesis
fatty acids
e.g. acetyl CoA
what are the three steps of glycolysis that are different in glycolysis and gluconeogenesis
glucose -> G6P
F6P -> FBP
PEP -> pyruvate
G6P -> glucose enzyme
glucose-6-phosphatase
FBP -> F6P enzyme
FBPase
pyruvate -> PEP enzymes
pyruvate carboxylase then PEP carboxyl kinase (PEPCK)
why is alanine an inhibitor of glycolysis
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something to do with its use in gluconeogenesis
what is the first layer of regulation of gluconeogenesis
what is secondary level of regulation of gluconeogenesis
why is PFK the major flux-controlling enzyme in muscle
why is phosphofructokinase 1 the major flux controlling enzyme in muscle
how is phosphofructokinase 1 regulated by allosteric modulators
which states does each bind
ATP (upstream substrate) binds exclusively in T-state preventing F6P binding
F6P (substrate) bind exclusively in R state
AMP (downstream product) binds R-state preferentially and counters inhibitory effect of T-state
what is the first committed step of glycolysis and why
T-state vs R-state of PFK
T- ‘tense’ and R- ‘relaxed’
relaxed in active form of the enzyme
refers to active site, relaxed is more open and favours substrate binding
two ATP binding sites: one substrate and one inhibitor (exposed only in T-conformation)
