Post absorption processing of proteins Flashcards

1
Q

what are 5 uses of amino acids

A
proteini synthesis 
synthesis of nitrogen containing metabolites 
energy 
fatty acids/ketone bodies 
glucose/glycogen
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2
Q
what are these amino acids used to turn into (nitrogen containing compounds 
glycine
tyrosine
tyrptophan 
histidine
glycine/arginine
glycine/aspartate/glutamine
A
gly - haem
ty - dopamine, NA, A
trypto - serotonin 
his - histamine
gly/arg - creatine
gly/asp/glut - purine bases
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3
Q

what is kwashiorkor

A

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

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4
Q

what must happen if amino acids are to be stored as energy

A

the nitrogen must be excreted as can cause tremor, vomiting, cerebral oedema and death

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5
Q

what are the 3 steps of removal of ammonia

A

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)

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6
Q

what molecule must be used to transport ammonia to the liver and describe this process

A

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

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7
Q

describe the disposal of ammonia

A

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

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8
Q

what is the other name for pyridoxal phosphate

A

Vit B6

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9
Q

what is vitamin B6 used for

A

transamination and synthesis of non-essential amino acids
decarboxylation reactions required for neurotransmitter synthesis
haem synthesis
some aspects of energy metabolism and lipid synthesis

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10
Q

what can lack of vitamins B6 cause

A

anaemia (lack of haem)
neurological symptoms (lack of NT and lipid syn)
poor growth, skin lesions, poor immune reposes (lack of protein syn)

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11
Q

what stimulates the activation of the urea cycle

A

high levels of amino acids

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12
Q

what is the control step in urea synthesis

A

carbamoyl phosphate synthesis

it is allosterically activated by N-acetylglutamate, which is formed when glutamate levels are high

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13
Q

what happens in the mitochondrion and then the cytosol in the urethras cycle

A

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

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14
Q

what is the difference between uric acid and urea

A

uric acid is derived from prune nucleotides rather than protein

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15
Q

what is the result of high uric acid in the blood

A

hyperuricaemia leads to deposition of sodium urate crystals in the kidneys (kidney stones) and in the joints (gout)

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16
Q

what is hyperuricaemia due to

A

over production of urate or poor excretion via the kidneys

high purine foods such as beer, red meat and seafood

17
Q

what 3 metabolic pathways use the carbon skeleton of amino acids

A

krebs - makes Atp
fatty acid and ketone synthesis
glucose synthesis - gluconeogenesis

18
Q

which two amino acids can only be ketogenic

A

lysine and leucine

19
Q

when does gluconeogenesis occur

A

during fasting or exercise

20
Q

where does gluconeogenesis usually occur

A

cytosol of the liver and kidney

21
Q

what are the precursors of glugoneogenesis

A
kept acids (derived from amino acids - mainly alanine) 
lactate - from anaerobic glycolysis 
glycerol from triglycerol breakdown
22
Q

how long do glycogen stores last

A

about 18 hours

23
Q

what are the three steps of gluconeogenesis

A

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)

24
Q

what causes glycolysis vs gluconeogenesis

A

high glucose and or low energy = glycolysis

low glucose and or high energy = gluconeogenesis

25
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
26
why is there rapid weigh loss in type 1 diabetes
to provide substrates for gluconeogenesis muscle protein is broken down to provide amino acids
27
what is the cori cycle used for
converts lactate from rapidly respiring tissues back to glucose which occur sin the liver
28
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