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Biochemistry - Victor > Dai 3 > Flashcards

Dai 3 Flashcards

0
Q

What cofactor is required for methylmalonyl –> succinyl coA

A

B12.

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1
Q

In the propionyl coA to succinyl coA pathway, what cofactor is required from propionyl to methylmalonyl coA

A

Biotin

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2
Q

What else requires B12?

A

homocysteine–>methionine. also needs THF cofactor

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3
Q

What is MMA methylmalonyl aciduria?

A

deficiency in methylmalonyl mutase. methylmalonyl coA increases, inhibits malonyl coA necessary for FA synthesis and myelination .

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4
Q

What carries CO2?

A

biotin

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5
Q

What carries CH3?

A

THF, SAM, B12

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6
Q

What carries methenyl, formyl, methylene?

A

THF

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7
Q

What is the methyl folate trap?

A

prevents methyl group deficiency when dietary methionine is low. methyl THF cant convert to other 1 C THF carriers.

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8
Q

folate to dihydrofolate to tetrahydrofolate. what enzyme

A

dihydrofolate reductase. during dihydrofolate deficiency, treat with formyl THF to bypass need for enzyme.

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9
Q

Why does alcoholism lead to thf deficiency.

A

alcoholism, causes impaired absorption.

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10
Q

How can you measure THF amount

A

direct test or figlu test (histidine-akg, uses thf as cofactor)

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11
Q

What processes are affected if THF is deficient?

A

defective purine pyr synthesis
homocys to met
glycine cleavage

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12
Q

What is required for transport and absorption of B12.

A

IF intrinsic factor.

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13
Q

What is pernicious anemia?

A

deficiency of IF.

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14
Q

Vitamin b12 is involved in two reactions in the body. which reactions.

A

homocysteine to methionine.
methylmalonyl coa to succinyl coa
regenerate THF.

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15
Q

Without ____, the methyl in methyl THF would be trapped in methylTHF form.

A

B12.

16
Q

T or F. Heme is made out of porphyrin ring, side chains and fe2+.

A

True.

17
Q

T or F. An important step in heme formation is making the correct asymmetric porphyrin.

A

True.

18
Q

8 ______+8________+Fe2+ –> Heme

A

glycine, succinyl coa

19
Q

What enzyme catalyzes the committed and rate limiting step in heme synthesis? What is this enzyme inhibited by.

A

ALA synthetase. inhibited by end products (heme).

20
Q

Defects early in heme synthesis leads to ________ symptoms. defects later cause __________ symptoms.

A

neuropsychiatric,

cutaneous.

21
Q

What is acute intermittent porphyria?

A

deficiency in PBG deaminase. Accumulation of PBG and ALA, both which are toxic. Characterized by “attacks” of paranoia, abdominal pain, anxiety. can be precipitated by drugs, infections, fasting, stress. Treatment by glucose and heme (glucose inhibits heme synthesis somehow)

22
Q

What is porphyria cutaneous tarda?

A

defect in uroporphoryinogen decarboxylase. photosensitivity, bullae, pigmentation.

23
Q

How can you treat PCT?

A
  1. avoid risk factors like etoh
  2. avoid sunc
  3. chloroquine can remove porphyrins for excretion
  4. beta carotene (free radical scavenger)
24
Q

During heme degradation, heme is taken up by macrophages and is converted to ________ and ________.

A

bilverdin (soluble)

bilirubin (insoluble)

25
Q

Bilirubin travels through blood while complexed with _____.

A

albumin.

26
Q

Bilirubin is ____ taken up by liver cells.

A

Actively

27
Q

Bilirubin is conjugated with 2 ______, making it more _______.

A

glucuronic acids.

soluble.

28
Q

Conjugated bilirubin is secreted by the liver into _____.

A

bile

29
Q

T or F. bacteria in intestine unconjugate bilirubin diglucuronide.

A

True.

30
Q

Bilirubin is oxidized to ______ in the intestine.

A

urobilinogen.

31
Q

T or F. Urobilinogen –> stercobilin or urobilin.

A

True.

32
Q

What is jaundice?

A

yellowing eyes/skin due to bilirubin deposition. due to increased bilirubin product or decreased excretion.

33
Q

What causes increased bilirubin or decreased excretion?

A 
excess hemolysis
liver dmg (decreased uptake, conjugation, secretion)
bile duct obstruction
34
Q

Why is unconjugated bilirubin in blood dangerous?

A

should be binding albumin. but when albumin already taken, it binds lipids, impairs membranes, especially nervous system.

35
Q

why does physiological neonatal jaundice occur? what is treatment?

A

liver not developed, low bilirubin glucuronyltransferase. treate with fluorescent light to make bilirubin more soluble isomer.

Biochemistry - Victor (17 decks)

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