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Biochemistry > First Pass Miss > Flashcards

First Pass Miss Flashcards

1
Q

What is required to make GLA proteins?

A

Vitamin K, napthoquinone, the hydroquinone form of it. It gets oxidized to an epoxide, and adds a CO2 to glutamate. Via glutamyl carboxylase

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2
Q

What is the function of Gla proteins?

A

Double negative charges stabilizes Ca+2, important for blood coagulation, bone / extracellular matrix homeostasis, and regulation of growth hormone.

-> deficiency = complications of vitamin K

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3
Q

What are the symptoms of ariboflavinosis?

A

irritation of skin + eyes, sensitivity to bright light, inflamed mouth + tongue, cracked lips

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4
Q

When must babies be supplemented with B2?

A

During blue light treatment for hyperbilirubinemia which destroys riboflavin

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5
Q

How can vitamin b3 be synthesized? What is it dependent on?

A

Via Tryptophan precursor, requires PLP (B6), a common enzyme in amino acid metabolism.

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6
Q

What does B3 deficiency cause?

A

Pellagra - 4 D’s: Dementia, dermatitis, diarrhea, death

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7
Q

What is the active form of B9 and what metabolic actions does it have?

A 
Tetrahydrofolate. Actions: Single carbon transfers
Homocysteine to methionine (with b12)
synthesis of thymidylic acid for DNA
Purine synthesis
Histidine + serine metabolism
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8
Q

What is the significance of the zinc-finger motif?

A

Protein motif utilized by nuclear hormone receptors to bind hormone response elements on DNA (for lipophilic hormones).

They work as dimer motifs

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9
Q

What nuclear hormone receptors does Retinoic acid bind?

A

RAR or RXR receptors, forming dimers

RXR only forms a heterodimer

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10
Q

What nuclear hormone receptors does calcitriol use?

A

VDR (vitamin D receptor). Can form a homodimer or heterodimer (with RXR).

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11
Q

What does vitamin A deficiency cause?

A
  1. Poor night vision / perforation of cornea / blindness
  2. Keratomalacia - ulceration and thinning of cornea
  3. Xerophthalmia - dryness and inflammation of cornea / conjunctiva
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12
Q

What does vitamin D deficiency cause? adults vs children

A

Osteomalacia + osteoporosis in adults

rickets in children

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13
Q

What is GEF vs GAP?

A

GEF: Guanine-nucleotide exchange factors - bind alpha subunit of GPCR to let it dissociate from beta / gamma
GAP: GTPase activating proteins - hydrolyze GTP on alpha subunit to deactivate it

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14
Q

What redox centers are at complex I?

A

FMN, FeS

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15
Q

What redox centers are at complex II?

A

FAD, Fe-S, B heme

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16
Q

What redox centers are at complex III?

A

Fe-S, B, C hemes

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17
Q

What redox centers are at complex IV?

A

Cu, A hemes

18
Q

What are copper redox centers?

A

Only at complex 4, they are binuclear centers of Cu-Cu or Cu-FE

19
Q

What are two alternative entrances into the respiratory chain other than glycerol-3-P on IMS side?

A
  1. Fatty Acyl-CoA DH - matrix side
  2. Dihydroorotate dehydrogenase - produces orotate in de novo pyridine synthesis.

All transfer to FAD and ultimately CoQ

20
Q

What are Heinz bodies?

A

hemoglobin aggregates in red blood cells diagnostic of hemolytic anemia (via pyruvate kinase or G6PDH problems)

21
Q

Why does metHb accumulate in hemolytic anemia?

A

PK or G6PDH is not working to properly re-reduce iron

22
Q

Why is PK deficiency hemolytic anemia not so bad?

A

Causes 2,3-BPG to accumulate in RBCs since the last step is prevented. Allows the subset of affected cells to more efficiently deliver oxygen.

23
Q

What is the inheritance pattern of G6PDH deficiencies?

24
Q

What causes acute hemolytic anemia?

A

Oxidative stress challenge when you cannot produce NADPH quick enough to stop damage due to G6PDH deficiency. Might not even realize you have this deficiency until you’re hit with it.

25
Which amino acids cannot be used for gluconeogenesis?
Leucine + Lysine
26
What is propionate?
Metabolite of odd-chain FA metabolism that can be converted to succinyl-CoA via B7 / B12
27
What is the metal-catalyzed Haber-Weiss reaction?
Superoxide is converted to oxygen, passing an electron to reduce Fe+3 to Fe+2. Fe+3 is re-oxidized, and passes an electron to hydrogen peroxide, creating hydroxyl radical and hydroxide ion
28
How is Nitric oxide formed?
Nitric oxide synthases - via the amino acid arginine
29
What happens as NO radical accumulates?
Competes with Oxygen at Complex 4 for binding, slowing respiratory chain and leading to more ROS production
30
What does NO radical react with? What does it become / its function?
Superoxide anion, forms peroxynitrite. It is a nitrating agent, and degrades by cleavage to OH and NO2 radicals, the latter which is a nitrating agent.
31
What starts lipid peroxidation?
Hydroxyl radical attacking polyunsaturated fatty acids, forming a radical that rearranges into conjugated dienyl radical.
32
How do conjugated dienyl radicals start a chain reaction of lipid peroxidation and how can this be stopped?
Dienyl radicals react with oxygen to form peroxyl radicals. These can react with nearby lipids to form another dienyl radical + make the original a lipid peroxyde. Can be stopped as a dienyl radical or peroxyl radical by vitamin E. Lipid peroxides must react with methionine residues in lipoproteins, otherwise they will degrade into aldehydes to form ALEs.
33
What amino acids react with radicals?
phenylalanine, lysine, tyrosine, and methionine
34
What is the most commonly measured indicator of DNA damage?
8-oxoguanine
35
What proteins chelate copper ions in plasma and brain?
plasma - albumin | brain - carnosine
36
What is meant by gluthionation and how is it reversed?
form bond between cysteine groups and GSH to prevent oxidative damage. Can be reduced by reducing the disulfide bond via thioredoxin or glutaredoxin
37
What are the functions of glyoxalase I and glyoxalase II? Why is this better then glutathione peroxidase (GPX)?
Glyoxalase I - Use GSH to convert methylglyoxal to a thioester Glyoxalase II - hydrolyze the thioester, forming lactate. GSH is regenerated here and does not need to be re-reduced.
38
What pathways form methylglyoxal?
Triose phosphate isomerase misfire Fatty acid and carbohydrate oxidation Glycine / threonine metabolism
39
What is glutathione peroxidase used for?
Reduction of lipid peroxides or hydrogen peroxide using GSH as a substrate. Needs to be re-reduced by glutathione reductase
40
What enzyme converts ferric to ferrous iron in hemoglobin?
Methemoglobin reductase
41
What does dehydroascorbate reductase use to re-reduce vitamin C?
GSH group or NADPH.
42
How is HOCl produced during phagocytosis?
Oxygen -> superoxide radical via NADPH oxidase 2 Superoxide radical to H2O2 and O2 via superoxide dismutase H2O2 to HOCl via myeloperoxidase

Biochemistry (14 decks)

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