Post absorption processing of proteins

Question 1

what are 5 uses of amino acids

Answer 1

proteini synthesis 
synthesis of nitrogen containing metabolites 
energy 
fatty acids/ketone bodies 
glucose/glycogen

Question 2

what are these amino acids used to turn into (nitrogen containing compounds 
glycine
tyrosine
tyrptophan 
histidine
glycine/arginine
glycine/aspartate/glutamine

Answer 2

gly - haem
ty - dopamine, NA, A
trypto - serotonin 
his - histamine
gly/arg - creatine
gly/asp/glut - purine bases

Question 3

what is kwashiorkor

Answer 3

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

Question 4

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

Answer 4

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

Question 5

what are the 3 steps of removal of ammonia

Answer 5

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)

Question 6

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

Answer 6

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

Question 7

describe the disposal of ammonia

Answer 7

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

Question 8

what is the other name for pyridoxal phosphate

Answer 8

Vit B6

Question 9

what is vitamin B6 used for

Answer 9

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

Question 10

what can lack of vitamins B6 cause

Answer 10

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

Question 11

what stimulates the activation of the urea cycle

Answer 11

high levels of amino acids

Question 12

what is the control step in urea synthesis

Answer 12

carbamoyl phosphate synthesis

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

Question 13

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

Answer 13

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

Question 14

what is the difference between uric acid and urea

Answer 14

uric acid is derived from prune nucleotides rather than protein

Question 15

what is the result of high uric acid in the blood

Answer 15

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

Question 16

what is hyperuricaemia due to

Answer 16

over production of urate or poor excretion via the kidneys

high purine foods such as beer, red meat and seafood

Question 17

what 3 metabolic pathways use the carbon skeleton of amino acids

Answer 17

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

Question 18

which two amino acids can only be ketogenic

Answer 18

lysine and leucine

Question 19

when does gluconeogenesis occur

Answer 19

during fasting or exercise

Question 20

where does gluconeogenesis usually occur

Answer 20

cytosol of the liver and kidney

Question 21

what are the precursors of glugoneogenesis

Answer 21

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

Question 22

how long do glycogen stores last

Answer 22

about 18 hours

Question 23

what are the three steps of gluconeogenesis

Answer 23

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)

Question 24

what causes glycolysis vs gluconeogenesis

Answer 24

high glucose and or low energy = glycolysis

low glucose and or high energy = gluconeogenesis

Question 25

what is type 1 diabetes affect on glycolysis and gluconeogenesis

Answer 25

no insulin is produced
glycolysis is inhibited therefore blood glucose levels rise

gluconeogenseis is stimulated and blood glucose rise even further

Question 26

why is there rapid weigh loss in type 1 diabetes

Answer 26

to provide substrates for gluconeogenesis muscle protein is broken down to provide amino acids

Question 27

what is the cori cycle used for

Answer 27

converts lactate from rapidly respiring tissues back to glucose which occur sin the liver

Question 28

how does alcohol make you hungry

Answer 28

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