Post absorption processing of proteins Flashcards
what are 5 uses of amino acids
proteini synthesis synthesis of nitrogen containing metabolites energy fatty acids/ketone bodies glucose/glycogen
what are these amino acids used to turn into (nitrogen containing compounds glycine tyrosine tyrptophan histidine glycine/arginine glycine/aspartate/glutamine
gly - haem ty - dopamine, NA, A trypto - serotonin his - histamine gly/arg - creatine gly/asp/glut - purine bases
what is kwashiorkor
low protein high fibre diet in children of developing countries
poor growth from lack pf proetin and well as immunosuppression as low IG’s
lack of melanin = skin changes
lack of albumin causes lower limb oedema
abdominal bloating from accumulation of fat in the liver and fluid build up
what must happen if amino acids are to be stored as energy
the nitrogen must be excreted as can cause tremor, vomiting, cerebral oedema and death
what are the 3 steps of removal of ammonia
transamination - transfer of amino group from amino acid to a-ketoglutarate forming glutamate (in most tissues)
deamination - release of ammonia from glutamate (mainly in the liver)
urea synthesis - urea cycle (in the liver)
what molecule must be used to transport ammonia to the liver and describe this process
as glutamate or glutamine
amino group from a-KG forms glutamate and another amino group forming glutamine
the reaction is then reversed in the liver to release ammonia
describe the disposal of ammonia
step 1 - transfer of amino group from amino acids in a-KG to form glutamate - requires pyridoxal phosphate
step 2 - release of ammonia from glutamate
what is the other name for pyridoxal phosphate
Vit B6
what is vitamin B6 used for
transamination and synthesis of non-essential amino acids
decarboxylation reactions required for neurotransmitter synthesis
haem synthesis
some aspects of energy metabolism and lipid synthesis
what can lack of vitamins B6 cause
anaemia (lack of haem)
neurological symptoms (lack of NT and lipid syn)
poor growth, skin lesions, poor immune reposes (lack of protein syn)
what stimulates the activation of the urea cycle
high levels of amino acids
what is the control step in urea synthesis
carbamoyl phosphate synthesis
it is allosterically activated by N-acetylglutamate, which is formed when glutamate levels are high
what happens in the mitochondrion and then the cytosol in the urethras cycle
mito - carbamoyl phosphate formed from ammonia and bicarbonate (CO2)
carbamyol group transferred to ornithine to form citrulline
in the cytosol – second amino group added from aspartate, arginine formed - urea released
what is the difference between uric acid and urea
uric acid is derived from prune nucleotides rather than protein
what is the result of high uric acid in the blood
hyperuricaemia leads to deposition of sodium urate crystals in the kidneys (kidney stones) and in the joints (gout)
what is hyperuricaemia due to
over production of urate or poor excretion via the kidneys
high purine foods such as beer, red meat and seafood
what 3 metabolic pathways use the carbon skeleton of amino acids
krebs - makes Atp
fatty acid and ketone synthesis
glucose synthesis - gluconeogenesis
which two amino acids can only be ketogenic
lysine and leucine
when does gluconeogenesis occur
during fasting or exercise
where does gluconeogenesis usually occur
cytosol of the liver and kidney
what are the precursors of glugoneogenesis
kept acids (derived from amino acids - mainly alanine) lactate - from anaerobic glycolysis glycerol from triglycerol breakdown
how long do glycogen stores last
about 18 hours
what are the three steps of gluconeogenesis
pyruvate - phosphoenolpyruvate
(requires many stages)
fructose 1-6 bisphosphate - fructose 6 phophate
(requires fructose 1,6 bisphosphatase)
glucose 6 phosphate - glucose
(requires glucose 6 phophatase)
what causes glycolysis vs gluconeogenesis
high glucose and or low energy = glycolysis
low glucose and or high energy = gluconeogenesis
what is type 1 diabetes affect on glycolysis and gluconeogenesis
no insulin is produced
glycolysis is inhibited therefore blood glucose levels rise
gluconeogenseis is stimulated and blood glucose rise even further
why is there rapid weigh loss in type 1 diabetes
to provide substrates for gluconeogenesis muscle protein is broken down to provide amino acids
what is the cori cycle used for
converts lactate from rapidly respiring tissues back to glucose which occur sin the liver
how does alcohol make you hungry
inhibits gluconeogenesis and lowering blood glucose
high NADH tends to cause conversion of pyruvate and alanine to lactate
this prevents conversion of glycerol to glyceraldehyde 3 phosphate which inhibits gluconeogensis
