Metabolism pathways Flashcards
glycogenesis
conversion where enzymes (3) activate (1) inhibit (2)
glycogen synthesis
glucose -> glycogen in cytosol in fed state
glycogen synthase (activated by high glucose)
UDP-glucose phosphorylase
amylotransglycosylase
↓ glucagon and adrenaline (inhibit glycogen synthase by phosphorylation)
↑ insulin (stimulate glycogen synthase by dephosphorylation)
glycogenolysis
conversion where enzymes (3) activate (4) inhibit (2)
glycogen metabolism
glycogen -> glucose in cytosol of muscle and liver
glycogen phosphorylase
debranching enzyme
hexokinase
↑ glucagon, adrenaline (stimulate glycogen phosphorylase by phosphorylation), Ca2+ and AMP (allosterically)
↓ insulin and glucose
glycolysis
conversion
where
enzymes (3)
glucose -> 2 pyruvate + 2ATP + 2NADH in cytosol
7ATP
hexokinase
phosphofructokinase
pyruvate kinase
Cori cycle
conversion
enzymes (1)
glucose -> pyruvate -> lactate -> pyruvate -> glucose
anaerobic
lactate hydrogenase
Link reaction
conversion
enzymes (1)
inhibit (1)
stimulate (1)
pyruvate + CoA -> acetyl coA + CO2 in mitochondrial matrix
PDH (pyruvate dehydrogenase)
PDH kinase inhibits and phosphorylises PDH
PDH phosphatase stimulates and dephosphorylises PDH
TCA cycle
conversion
enzymes (2)
acetyl coA -> 20ATP in mitochondrial matrix
citrate synthase
isocitrate dehydrogenase
alpha-ketoglutarate dehydrogenase
pentose phosphate pathway (PPP)
conversion
enzymes (1)
glucose -> pyruvate to make NADPH in cytosol
glucose-6-P dehydrogenase
gluconeogenesis
conversion
where
enzymes (2)
activate (3)
non-carbohydrate -> glucose in liver
pyruvate carboxylase
phosphoenoylpyruvate
↑ glucagon, acetyl coA, cortisol
transamination
conversion
examples of a substrate (3)
example of conversion (2)
enzymes (2)
transfer of α-amino acid to α-ketoacid -> amino acid
α-ketoacid e.g. oxoaloacetate, pyruvate, α-ketoglutarate
e. g. α-amino group + oxaloacetate -> glutamate
e. g. α-amino group + pyruvate -> alanine
aminotransferase
pyridine (B6)
removal of ammonia from brain
conversion
enzymes (3)
ammonia -> glutamine
glutamate dehydrogenase
glutamine synthase
to liver for oxidative deamination
glutamine -> glutamate + NH4+
glutaminase
removal of ammonia from muscle
conversion
enzymes (1)
ammonia -> alanine
glutamate dehydrogenase
aminotransferase
to liver
urea cycle
conversion
where
rate limiting step with enzyme
another step with enzyme
ammonia -> urea in liver
rate limiting step: NH4+ + CO2 + H2O -> carbamolyl phosphate (carbamolyl phosphate synthase)
arginine -> urea + ornithine (arginase)
1 lipolysis of triglycerides
converison
enzymes (1)
activate (2)
inhibit (1)
triglyceride -> glycerol + 3 fatty acids
lipase
↑ glucagon and adrenaline
↓ insulin
2 fate of glycerol in liver
conversion
enzymes (1)
glycerol -> dihydroxyacetone phosphate (DHAP)
glycerolkinase
3 fatty acids activated in cytosol
conversion
enzymes (1)
transport where and how
fatty acid + coA -> fatty acyl coA (activated fatty acid)
fatty acyl coA synthase
to mitochondria by CAT shuttle
↑ palmityol coA for CAT II
↓ maolonyl coA for CAT I
4 activated fatty acid undergoes β-oxidation
fatty acyl coA -> fatty acyl coA (shortened by 2C) + acetyl coA
5 acetyl coA in HMG-CoA cycle
ketogenesis: acetyl coA -> ketone bodies
catabolism
break down large molecules to forming small substances and release energy using enzymes
oxidation of nutrients (hydrogenation)
anabolism
use useful forms of energy and small molecules to make large molecules
reduction of nutrients (dehydrogenation)
regulation of reactions (3)
enzyme (substrate supply, rate limiting step, allosteric control)
hormone-mediated reversible phosphorylation of key control enzyme
hormone affecting rate of pathway by enzyme induction/ stimulating enzyme stimulation
oxidative deamination
conversion
use
amino acid -> ketoacid + NH4+
ketoacids oxidised for energy for TCA cycle and ketogenesis
stages of fatty acid synthesis
transport of citrate into cytosol from mitchondria by citrate shuttle
citrate -> acetyl coA + oxaloacetate
activation using acetyl coA carboxylase
acetyl coA -> malonyl coA
addition of 2C in 4 steps all by fatty acid synthase
formation of cholesterol
HMG CoA reductase stimulated by insulin dephosphorylating
acetyl coA -> cholesterol
chhylomicrons (CM)
transport lipids from gut to rest of body by blood via lymphatics
