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McG > Quiz 8 > Flashcards

Quiz 8 Flashcards

1
Q

what way can THF ox/red reactions go

A

methylene can go to methenyl OR methyl

methyl CANNOT be oxidized further

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2
Q

what AA can react with THF

A

serine+THF glycine + 3

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3
Q

what is the glutamic acid reaction

A

glutamate + NAD alphaKG + NADH+ NH3

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4
Q

how is glutamine produced

A

glutamate + NH3 + ATP –> Glutamine + ADP + Pi

*THIS is how we get ammonia from other cells to liver to it can undergo urea cycle

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5
Q

how is aspartate produced

A

transamination:

OAA –> Aspartate
Glutamate –> alphaKG

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6
Q

how is asparagine produced

A

Aspartate + glutamine + ATP –> Asparagine + glutamate + ADP + Pi

*GLUTAMATE can give aspartate and glutamine which can give asparagine

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7
Q

how is alanine produced

A

Amino transferase reaction

Pyruvate –> Alanine
Glutamate –> alphaKG

*exercising muscle is using a lot of glucose so lots of pyruvate being produced and exceeding capacity of PDH and LDH reactions. XS pyruvate converted to alanine, leaves muscle, goes to liver and gets converted back to pyruvate where it can undergo gluconeogenesis and then glucose can go back to muscle

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8
Q

what is the AA that cycles with gluc in exercising muscle

A

ALANINE. exercising muscle is using a lot of glucose so lots of pyruvate being produced and exceeding capacity of PDH and LDH reactions. XS pyruvate converted to alanine, leaves muscle, goes to liver and gets converted back to pyruvate where it can undergo gluconeogenesis and then glucose can go back to muscle

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9
Q

how is proline produced

A

glutamate –> gamma Glutamic semialdehyde –> ornithine and proline

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10
Q

what is ornithine produced from and what can it become

A

glutamate –> gamma glutamic semialdehude –> ornithine –> arginine (needs aspartate)

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11
Q

is arginine essential?

A

in adults, glutamate pathway is enough but in children it isnt so it is considered an essential AA

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12
Q

how is cysteine formed

A

methionine –> SAM –> SAH –> homocysteine + serine –> cysteine

*non essential as long as we have methionine and serine

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13
Q

how is tyrosine produced

A

phenylalanine –> tyrosine

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14
Q

how is serine produced

A

either from 3PGA in glycolysis or from reverse of folic acid reaction

glycine + THF –> serine (REVERSIBLE!)

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15
Q

how is glycine produced

A

glycine + THF –> Serine + methyleneN5N10THF

OR

de novo from CO2 + ammonia + methylene THF

(methylene can come from histidine or another serine)

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16
Q

what are catecholamines

A

DOPA, dopamine, norepi, epi

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17
Q

where are catecholamines synthesized

A

in brain as adrenals, function as neurotransmitters and regulators of blood flow, BP, metabolism, and E production

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18
Q

what is parkinsons caused by

A

deficiency in dopaminergic neurons in substantia nigra of brain. tx with DOPA which can cross BBB, while dopamine cannot

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19
Q

catecholamine path

A

tyrosine –> DOPA + DHB + H2O–>Dopamine –> Norepi –> Epi

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20
Q

dopa to dopamine

A

dopa decarboxilase with PLP (loses CO2)

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21
Q

dopamine to norepi

A

OH in, cofactor is vit C

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22
Q

norepi to epi

A

SAM, CH3 is put on

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23
Q

tyrosine to DOPA + DHB + H20

A

tyrosine hydroxylase, THB + O2

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24
Q

what is GSH produced from

A

3 Amino Acids (glutamate, cysteine, glycine)

Glutamate + cysteine + ATP –> glu-cys + glycine + ATP –> GSH

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25
Q

what can tryptophan produce (not in brain)

A

acetyl coA/NH4/CO2 via tryptophan deoxygenase

NOTE: some metabolites can produce NAD and NADP

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26
Q

what is pellagra caused by

A

deficiency in tryptophan

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27
Q

what does tryptophan metabolize to in the brain

A

5 hydroxytryptophan –> serotonin (neurotransmitter, vasoconstrictor, important for blood pressure) –> melatonin

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28
Q

how does serotonin become melatonin

A

SAM becomes SAH

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29
Q

how does 5HT become serotonin

A

decarbox with PLP as cofactor

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30
Q

how is creatine produced

A

glycine + arginine –> guanidoacetate + ornithine –> creatine

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31
Q

what can creatine produce

A

creatine +ATP –> creatine phosphate –> creatinine

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32
Q

what is important about creatine phosphate reaction

A

reversible so it can produce ATP, one of the ways that our body stores ATP for muscle and brain. different isoforms in diff tissues so can be diagnostic for heart attack, stroke, etc

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33
Q

decarbox of glutamate gives

A

GABA - inhibitory neurotransmitter (PLP cofactor)

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34
Q

decarbox of histidine gives

A

histamine - vasodilator, allergic rxns, protein digestion (PLP cofactor)

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35
Q

decarbox of serine

A

ethanolamine (base in phospholipid phosphatidyl ethanolimine) PLP cofactor

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36
Q

decarbox of ornithine

A

putrescine (precursor to DNA binding polyamine spermine) PLP cofactor

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37
Q

how is nitric oxide produced

A

ariginine + oxygen –> nitric oxide

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38
Q

what is function of nitric oxide

A

vasodilator, regulates BP, prevents platelet aggregation. given after heart attacks

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39
Q

nitric oxide and bacteria

A

reacts with heme enzymes to block oxygen activation but also affects mammalian anzymes

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40
Q

what can aginine become

A

citrulline, ornithine, nitric oxide

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41
Q

what is heme important for

A

carrier for oxygen carrier proteins (hb), electron transfer enzymes (mito cytochomes), cyt p450 for drug metabolism

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42
Q

where is heme synthesized

A

mainly in liver and erythropoetic tissues but all do some. (initially in mito and then goes out to cytosol)

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43
Q

shape of heme

A

ring shaped with iron in the center

44
Q

how is heme synthesized

A
  1. succinyl coA + glycine –> delta ALA - leaves matrix
  2. 2 ALA condense –> PBG
  3. PBG x 4 –> uroporphyrinogen III which decarboxylates to give coprophorinogen which decarboxylates to give protophorinogen (BACK TO MITO!)
  4. Protophyrinogen 9 oxidized to Protophyrin
  5. Protophyrin with ferrochelatase gives Heme
45
Q

what steps of heme synthesis are inhibited by lead

A
  1. ALA dehydratase when two ALA condense to give PBG

2. Ferrochelatase with protophyrin becomes Heme

46
Q

what is the RL step of heme synthesis

A

succinyl coA + glycine –> ALA (IN MATRIX!)

47
Q

how is iron in blood carrier, how is iron in blood stored

A

carried as apotransferrin, stored as ferritin

48
Q

what function does ferritin have

A

antioxidant, binds iron so it cant undergo fenton reaction

49
Q

what are prophyrias

A

deficiencies in each of the enzymes in heme biosynthetic pathway result in accumulation of porphyrin substrates. MANY double bonds can be oxidized by ROS singlet O2

50
Q

heme breakdown time

A

RBCs Hb every 120 days, cytochromes 10-20 days

51
Q

heme breakdown pathway

A

heme –> bilverdin + CO –> bilirubin –> bilirubin albumin –> bilirubindiglucorinide (conjugated) –> bile –> urobilinogin (urine) and stercobilin

52
Q

what causes jaundice

A

accumulation of bilirubin - can be caused by lack of conjugation enzymes or blockage of bile duct

*conjugated bilirubin excreted in bile

53
Q

where in the heme breakdown pathway does it enter liver

A

bilirubin –> bilirubin albumin step

54
Q

how is IMP synthesized

A

Ribose 5P from PPP —> PRPP
PRPP + glutamine —> 5 ribosyl 1 amine + glutamate
*catalyzed by amido phosphoribosyl transferase

THIS turns into IMP

55
Q

what does IMP become

A

IMP + GTP + aspartate –> adenylosuccinate –> adenylate (AMP)

IMP + NAD –> xanthyalate —> Guanylate (gluatmine gives amino, becomes glutamate)

56
Q

purine salvage pathway

A

RNA constantly being degraded - can be excreted as uric acid or salvaged

  1. Adenine phosphoribosyl transferase catalyzes: Adenine + PRPP –> AMP
  2. Hypoxanthine guanine phosphoribosyl transferase catalyzes:
    hypoxanthine + PRPP —> IMP
    guanine + PRPP –> GMP
57
Q

what is lesch nyhan syndrom caused by

A

absence of hypoxanthine guanine phosphoribosyl transferase … makes IMP so can reproduce AMP and GMP

58
Q

purine breakdown

A

GMP – guanosine – guanine – XANTHINE
AMP – IMP – inosine – hypoxanthine – XANTHINE

xanthine ultimately gets oxidized to uric acid which gets excreted

59
Q

gout

A

XS uric acid forms - can inhibit xanthine oxidase (and therefore uric acid) with allopurinol

*colchicine and methotrexate block inflammatory reaction which is activated in response to high uric acid

60
Q

how is UMP synthesized

A

glutamine + CO2 + 2 ATP —> carbamoyl phosphate –> orotic acid –> UMP

61
Q

what is carbamoyl phosphate synthase used in

A

urea cycle and synthesis of pyrimidines

62
Q

what is aspartates function in pyrimidine synthesis

A

reacts with carbamoyl phosphate to make orotic acid

63
Q

what could high levels of orotic acid be caused by

A

decreased ornithine transcarbamylase in urea cycle so carbamoyl phosphate enters into pyrimidine synthesis pathway

64
Q

how do you get from RNA to DNA

A

ribonucleotide diphosphate reacts with NADPH catalyzed by RR to give deoxyribonucleotide diphosphate

65
Q

steps in RR

A
  1. ATP binds active site, signals to synthesize pyrimidines
  2. dCMP and dUMP formed, eventually dTTP formed.
  3. dTTP in binding site signals purines to be synthesized
  4. dGMP synthesized, eventually triggers dAMP which converts to dATP
  5. dATP in activity site shuts down enzyme
66
Q

sites on RR

A
  1. active site where catalysis takes place, has thiol sites
  2. activity site
  3. substrate specificity site
67
Q

SCIDS

A

due to deficiency of adenosine deaminsae, important in degradation of ATP to dATP to hypoxanthine and xanthine, get low b and T cells and low immune response

68
Q

what would a test of high orotic acid in a newborn suggest

A

urea cycle deficiency

69
Q

what does thioredoxin do

A

supplies necessary electrons to RR. in this process it gets oxidized, gets reduced back by thioredoxin reductase which gets its electrons via FADH2

70
Q

glucogenic AA

A

produce pyruvate or any TCA cycle intermediate. All except leucine and somewhat lysine

71
Q

ketogenic AA

A

produce Acetyl coA or acetoacetate. Leucine, Lysine, Isoleucine, Tryptophan, Phenylalanine, Tyrosine

72
Q

C3 Family

A

5 OF THEM

Tryptophan 
Alanine 
Glycine 
Serine 
Cysteine

ALL GO TO PYRUVATE

“Try to get AL to take GLYstening SERiously for his CYS”

73
Q

C4 family

A

2 OF THEM

Asparagine and aspartate
*Aspartate removed to OAA into cycle

74
Q

C5 family

A

5 OF THEM

Histidine 
Proline
Arginine
Glutamine
Glutamate

ALL GET TRANSFERRED TO alpha KG

HIS PROblems ARe that his is too GLUttonous (x2)

75
Q

succinyl coA via AA

A

Valine
Isoleucine
Threonine
Methionine

All go to succinyl CoA

VAL IS only THREe and does METh which SUCks

rxn: methionine - homocysteine - alphaKB- propionyl coA - methylmalonyl coA - succinyl coA

76
Q

branched AA breakdown

A

valine, isoleucine, leucine

transamination to alpha keto acid, oxidative decarboxylation to produce CO2 and acyle coA product

77
Q

leucine breakdown

A

acyl coA from leucine only to acetyl coA and acetoacetate, ONLY KETOGENIC

78
Q

valine and isoleucine breakdown

A

goes to propionyl coA to methylmalonyl coA to succinyl coA so GLUCOGENIC

isoleucine can also produce acetyl coA so also ketogenic

79
Q

maple syrup urine disease

A

acyl coA dehydrogenase doesnt work so get build up of alpha keto acids which make urine smell like maple syrup

80
Q

what happens to phenylalanine during breakdown

A

turns into tyrosine + DHB which can turn into fumarate or acetoacetate – ketogenic and glucogenic

81
Q

what happens if you are mussing phenylalanine hydroxylase

A

phenylketonuria because phenylalanine accumulates and enters other side pathways it normally wouldnt enter

82
Q

what could cause black urine

A

tyrosine metabolism issue - accumulation of homogenestic acid which usually goes to fumarate

83
Q

what are ways we can treat inborn errors of metabolism

A
  • Restrict substrate
  • Provide cofactors
  • Provide product
  • Replace enzyme
  • Provide alternate routes of elimination
  • Treat secondary effects
84
Q

PKU

A

Phenylketonuria - happens when there is a backup of phenylalanine because it cant become tyrosine –> dopamine –> melanin

85
Q

what is the enzyme affected in PKU

A

phenylalanine hydroxylase with cofactor of tetrahydrobiopterin

86
Q

how to treat PKU

A

restrict substrate – diet with no phenylalanine.
ADD tyrosine

  • Can also give cofactor now
  • can also replace enzyme now – clinical trials underway right now
87
Q

outcome of treated PKU

A

PKU used to only be treated for 6 years of life - now have treatment for life

88
Q

maternal PKU outcome

A

microcephaly, congenital heart disease, craniofacial abnormalities, small for gestational age

89
Q

cofactor metabolism in PKU

A

tetrahydrobiopterin deficiency. Increased phenylalanine, decreased dopamine and serotonin because also involved in tyrosin and tryptophan metabolism

90
Q

malignant PKU

A

when there is an issue with the cofactor. cant metabolize phenylalanine, tyrosine, OR tryptophan

91
Q

organic acidemia

A

inborn error where pathway intermediate that is elevated is a non amino organic acid (no NH3)

92
Q

organic acidemia labs

A

HIGH plasma ammonia
severe metabolic acidosis
acid metabolites in urine

93
Q

metabolism of propionyl coA

A

propionyl coA carboxylase turns it into methylmalonyl coA. without this enzyme get back up!

*BIOTIN is cofactor

94
Q

treatment of propionic acidemia

A

restrict substrate - VOMIT free formula

VOMIT = Valine, OCFA, methionine, isoleucine, threonine.

Provide biotin cofactor

Can give alternate path of elimination (carnitine can bind and eliminate propionic acid)

Treat secondary affects - ammonia detox and add bicarb to neutralize the acid

95
Q

OTC deficiency

A

deficient in urea cycle - carbamoyl phosphate will go to pyrimidine synthesis. Ammonia will be extremely elevated

96
Q

OTC treatment

A

only essential AAs, provide product of citruline, replace the enzyme with a liver transplant, dialysis to remove ammonia + ammonia scavenging meds

97
Q

galactosemia

A

missing uridyl transferase - cant get from galactose 1 P to glucose 1P

98
Q

tx of galactosemia

A

restrict substrate (no lactose or galactose),

99
Q

GSD1

A

glycogen storage disease - glucose will be very low, lactate elevated, triglycerides elevated, uric acid elevated. blood sugars fall VERY fast after short fast

100
Q

enzyme in GSD1

A

G6Phosphatase - cant regenerate glucose

101
Q

medium chain acyl coA dehydrogenase deficiency (MCAD)

A

cant oxidize medium chain fatty acids, usually first manifestation is sudden death. fasting hypoketotic hypoglycemia because cant do beta ox of fatty acids

102
Q

how to treat MCAD

A

avoid fasting, lower fat, higher carb diet. Add carnitine to bind and eliminate FA, treat secondary effects

103
Q

Gauchers

A

accumulation of storage material in lysosomes - get erlenmeyere flask femur. ALL caused by mutations in B glucocerebrosidase. - cant make fatty acids which include plasma membrane sphingolipids

104
Q

heteroplasmy and threshold effect

A

relevant in mitochondrial diseases as have all diff mit and only some will express issue.

105
Q

replicative segregation

A

random allotment of daughter cells during cellular replication so some cells much more affected than others - some body parts more affected than others

McG (11 decks)

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