week 1- Carbohydrate and metabolism Flashcards
what is catabolism
processes in which complex substances are degraded to simpler molecules
what is anabolism
processes concerned primarily with the synthesis of complex organic molecules
what is catabolism associated with
net release of chemical energy
what is anabolism associated with
net input of energy required
what is glycolysis
releasing energy from glucose
what is gluconeogenesis
process in which body maintains glucose levels from non-carbohydrate sources (reverse glycolysis)
what is the 6th step of glycolysis
GADPH reduces NAD+ to NADH
why is NADH re oxidised
because cytoplasm has a finite supply of NAD+
what is a fermentation
an energy-yielding metabolic pathway with no net change in the oxidation state of products compared to substrates
where does homolactic fermentation occur
animal cells, and lactic acid bacteria
where does alcoholic fermentation occur
in yeast
what does anaerobic glycolysis lead to
pyruvate
what happens to pyruvate produced in anaerobic glycolysis
it is reduced, so no net oxidation of glucose occurs
what is lactate formed by
active skeletal muscle
what are the primary gluconeogenic tissues?
liver and the kidney cortex
when does the body make glucose
- long periods in the absence of carbohydrates
- intense exercise
what does gluconeogenesis use to bypass irreversible reactions of glycolysis
enzymes
which enzymes does gluconeogenesis use to bypass the conversion of pyruvate to phosphoenol-pyruvate
- pyruvate carboxylase
- phosphoenolpyruvate carboxykinase
what is pyruvate converted to by pyruvate carboxylase
oxaloacetate
what is oxaloacetate converted to by phosphoenolpyruvate carboxykinase
phosphoenol-pyruvate
what reaction converts fructose-1,6-bisphosphate to fructose-6-phosphate
hydrolytic reaction catalysed by fructose-1,6-bisphosphatase
what non-carbohydrate precursors can glucose be synthesises by
Amino acids
Glycerol
Lactate
what does the hydrolysis of triacylglycerol yield
glycerol and fatty acids
can animals convert fatty acids into glucose
no
what mechanism is involved in the synthesis of glucose from lactate
the cori cycle
what is the cori cycle
Lactate produced in glycolysis during muscle exertion is transported to the liver, for resynthesis of glucose by gluconeogenesis.
Transport of glucose back to muscle for synthesis of glycogen, and its reutilization in glycolysis, completes the cycle.
how is glycolysis and gluconeogenesis regulated
reciprocally
what is glycolysis determined by
glucose availibility
what is gluconeogenesis determined by
precursor availability
what are the enzymes involved in the regulation of glycolysis and gluconeogenesis
phosphofructokinase
fructose-1,6-bisphosphatase
pyruvate kinase
pyruvate carboxylase
phosphoenolpyruvate carboxykinase
what is phosphofructokinase stimulated and activated by
stimulated by high levels of AMP
activated by fructose-1,6-bisphosphate
what is phosphofructokinase inhibited by
high levels of ATP and citrate
what is Fructose-1,6-Bisphosphatase stimulated by
high levels of citrate
what is Fructose-1,6-Bisphosphatase inhibited by
high levels of AMP and Fructose-2,6-Bisphosphate
what is pyruvate kinase activated by
Fructose-1,6-Bisphosphate
what is pyruvate kinase inhibited by
high levels of ATP and alanine
what is pyruvate carboxylase activated by
high levels of acetyl-CoA
what is carboxylase inhibited by
high levels of ADP
what is Phosphoenolpyruvate carboxykinase (PEPCK)
high levels of ADP
which state is insulin released in
when there are high blood sugar levels (the fed state)
what does insulin stimulate
expression of genes encoding the proteins of glycolysis
what does insulin inhibit
glyconeogenesis by switching off expression of Phosphoenolpyruvate carboxykinase
what does glucagon stimulate
glyconeogenesis by switching on expression of phosphoenolpyruvate carboxykinase & Fructose 1,6, Bisphosphatase
what does glucagon inhibit
expression of genes encoding the proteins of glycolysis
