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FMS > [FMS] NAM - amino acid metabolism > Flashcards

[FMS] NAM - amino acid metabolism Flashcards

1
Q

what is the average adult protein turnover?

What are the body’s protein requirements?

A

turnover 300-400g/day

recommendation: 50 – 70 g protein per day

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2
Q

what is the half-life of proteins?

A

most proteins have half-lives of several days

structural proteins have half-lives of years

Hormones & digestive enzymes are degraded very rapidly, with half-lives of minutes.

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3
Q

what is the recommendation of protein daily?

A

50-70g

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4
Q

how many essential amino acids are there?

A

20

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5
Q

which 10 amino acids can the body synthesize on its own

A

remember “private tim hall”

P = phenylalanine
V = valine
T = threonine
T = tryptophan
I = isoleucine
M = methionine
H = histidine
A = arginine
L = leucine
L = lysine

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6
Q

what is nitrogen balance?

A

N (intake) = N (excretion)

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7
Q

nitrogen excretions are in what form?

A
  • urea
  • uric acid
  • creatinine
  • NH4+
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8
Q

what is a positive nitrogen balance?

A

N (intake) > N (excretion)

intake more than excretion

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9
Q

when does a positive nitrogen balance occur

A
  • normal children growth
  • convalescence after serious illness
  • in pregnancy
  • after immobilisation after accident
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10
Q

what is a negative nitrogen balance?

A

N (intake) < N (excretion)

excretion more than intake

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11
Q

when does a negative nitrogen balance occur

A
  • in starvation
  • during serious illness
  • late cancer stages - cachexia
  • injury and trauma

^ If not corrected and becomes prolonged, there will be irreversible loss of essential body tissue
will ultimately lead to death.

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12
Q

what is the pathway of protein degradation for cellular proteins

A
  • If they are recognised as ‘old’ or damaged they are removed by the ubiquitin breakdown system
  • They are a mixture of the 20 amino acids
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13
Q

what is the pathway of protein degradation for exogenous proteins

A
  • ‘old’ or damaged sub cellular organelles are taken into vesicles by endocytosis, or autophagocytosis. The vesicle fuses with lysosomes and proteolytic enzymes degrade proteins into amino acids
  • Starvation and hormones (e.g. cortisol increase) rates of protein breakdown in muscle
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14
Q

what are amino acids degraded into? ie what are amino acids made of?

A

It is an oxo (keto) acid with an amine group.

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15
Q

what are the two processes of aa degradation?

A

oxidative deamination and transamination

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16
Q

What is transamination?

A

transfer of the amino group of an amino acid onto a keto acid to produce the amino acid of that keto acid and the keto acid of that amino acid.

17
Q

what does transmination need?

A
  • amino acid
  • keto acid
  • aminotransferase with pyridoxal phosphate
18
Q

outline what happens in deamination

A
19
Q

outline what happens in transamination

A

remember: TRANSamination = TRANSfer

20
Q

what is the fate of oxo-acids in starvation?

A

carbon skeletons of 13 amino acids converted back to glucsoe by liver, these are classified as ‘glucogenic’.

21
Q

what are ketogenic amino acids

A

Leucine and lysine

^ These can only be degraded to acetyl CoA, not pyruvate

22
Q

what are the 5 glucogenic and ketogenic amino acids?

A

phenylalanine, tyrosine, tryptophan, isoleucine, threonine

REMEMBER: PITTT

23
Q

what is the difference between glucogenic and ketogenic amino acids and its ability to be converted to glucose?

A

glucogenic = can be converted back to glucose by liver

ketogenic = cant be converted back to glucose, can only be degraded to acetyl coA, leucine, lysine

24
Q

What are the important amino acids in the inter-organ transport of nitrogen?

A
  • Alanine - can be deaminated into pyruvate but not directly
  • Glutamate - can be deaminated into pyruvate directly
  • Glutamine - can be deaminated into pyruvate but not directly, goes to glutamate to alpha-ketaglutarate.
  • Aspartate - can be deaminated into pyruvate but not directly, goes to oxaloacetate.
25
Q

3 Important features of glutamine

A

safe carrier of ammonia in the blood
^ Ammonia is toxic to the brain

Glutamine can carry 2 ammonia equivalents to the liver for urea formation

Glutamine can deliver ammonium ions to the kidney for pH regulation (buffering H+)

26
Q

where does urea cycle take place

A

cytosol/ mitochondrial matrix

27
Q

explain urea cycle and enzymes involved

A
28
Q

What are the 4 end products of nitrogen metabolism?

A
  • Urea - protein breakdown
  • Creatine - creatine phosphate breakdown
  • Uric acid - DNA and RNA breakdown
  • Ammonia (NH4+) - control of body pH
29
Q

What does the build up of ammonia cause?

A
  • Ammonia is neurotoxic
    • The exact mechanism is not known
    • It causes cerebral oedema, coma and death
    • Seems to involve cell death
30
Q
  • How do you get an impaired conversion of NH3 to urea (hyperammonaemia)?
A
  • Liver failure - (viral hepatitis, ischaemia, liver cirrhosis, toxins eg aflatoxin in mouldy peanuts)
  • Genetic defects - reduction in catalytic activity of any enzyme of the urea cycle
31
Q

what is the name of the condition for exessive ammonia concentration? what is the treatment

A

hyperammonaemia, treatment = dialysis

32
Q

what does urea do?

A

protein breakdown

33
Q

what does creatine do

A

creatine phosphate breakdown

34
Q

what does uric acid do?

A

DNA + RNA breakdown

35
Q

what does ammonia do?

A

body pH control

36
Q

Why are alanine and aspartate transaminases important diagnostically?

A

They are markers for liver damage.

37
Q

Plants and micro organisms can synthesise all 20 amino acids from what?

A

NH3 and CO2

38
Q

whats the difference between what happens to glucogenic amino acids and ketogenic amino acids?

A

glucogenic –> goes to pyruvate, TCA

keotgenic –> goes to acetyl CoA

FMS (33 decks)

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