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Uworld > Biochem > Flashcards

Biochem Flashcards

1
Q

2,3 - BPG binding site/type

A

ionic bond with Beta subunit of HgbA

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2
Q

high methionine = which aa now essential

which enzyme def

name

A

cysteine

defect in cystathione synthetase

homocystinuria

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3
Q

Lens sublixation down and in

A

homocysteinuria

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4
Q

Lens sublixation upward

A

Marfans

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5
Q

Enzyme def in homocysteinuria and tx(2)

A
  • Cystathionine synthase (with B6)
    tx: cysteine, up up B6
  • homocysteine methyl transferase (?aka methionine synthase)(with B12)
    tx: methionine, B12
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6
Q

symp homosysteinuria

A 
intellectual dis
osteoporosis
TALL stature
lens sublixation (down and in)
thromosis
atherosclerosis (MI, stoke)
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7
Q

homeless, increased fatigability, exertional dsypnea, LE edema, cardiac dilation, increased CO… nutrient def

A

B1 (thiamine)

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8
Q

wrinkles - cause

A

decreased collagen fibril production - net loss of dermal collagen and elastin

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9
Q

RNA between 74 and 93 nucleiotides

A

tRNA

*contains unusual nucleosides such as pseudouridine and thymidine

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10
Q

3’ end of tRNA

A
  • CCA sequence (recognition sequence by proteins)
  • terminal OH
  • binding site for aa
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11
Q

acceptor stem of tRNA

A

3’/5’ ends

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12
Q

enzyme that catalyzes loading of tRNA with aa

A

aminoacyl tRNA sythetase

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13
Q

D arm of tRNA

A

lots of dihydrouracil residues

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14
Q

T arm of tRNA

A

contains sequence necessary for binding to ribosomes - thymidine, pseudouridine, cytidine

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15
Q

RNA containing thymidine

A

tRNA

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16
Q

5’ end of tRNA

A

terminal phosphate

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17
Q

larger protein, altered fx, retained immune reactivity - type of mt?

A

spice site mutation

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18
Q

vitamin tx for measles

A

vit A

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19
Q

Dermatitis, Diarrhea, ….

A

Niacin def

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20
Q

Child with ataxia, pruritic skin lesions, loose stools + netural aromatic aas in urine

A

Hartnup:
imparied instinal and renal absorption of tryptophan

tryptophan:
niacin, serotonin, melatonin

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21
Q

precursor of the NAD+ coenzyme

A

tryptophan

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22
Q

skin blisters, increased plasma porphyrins… enzyme?

A

uroporphyrinogen decarboxylase

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23
Q

human enzyme that has reverse transciptase

A

telomerase

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24
Q

subperiosteal hemotomas

A

scurvy - ascorbic acid/vit C def

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25
Q

cytoplasmic p bodies

A

role in mRNA translation regulation and mRNA degredation

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26
Q

snRNPs participate in function of…

A

spliceosomes

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27
Q

pyruvate dehdrogenase: which aa can you supplement safetly; why

A

lycine and leucine

- exclusively ketogenic and will not increase blood lactate levels

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28
Q

pyruvate dyhdrogenase: fx

A

pyruvate –> acetyl CoA

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29
Q

pyruvate dehdrogenase: cofactors

A 
"TLC For Nobody"
Thyamine pyrophsophatase (B1)
Lipoic Acid
Co-enzyme A (B5)
FAD (B2)
NAD+ (B3)
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30
Q

What uses the same cofactors as PDH

A

alpha KG dehydrogenase

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31
Q

What B vitamins are cofactors for PDH and alpha-KG dehydrogenase

A

B1 (thiamine)
B2 (riboflavin)
B3 (niacin)
B5 (panthenoic acid/panthenate)

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32
Q

arsenic poisoning MOA/symp

A

blocks lipoic acid (cofactor of PDH and alpha-KG dehrogenase)

Sx:
garlic breath
rice water stool
vomiting

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33
Q

alpha-KG dehdrogenase fx

A

alpha-kg –> succinyl-CoA (TCA cylcle)

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34
Q

PDH complex def symp

A
  • build up of pyruvate gets shunted to lactate (via LDH) –> lactic acidosis
  • neurologic defects
  • high levels of serum alanine starting in infancy
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35
Q

PDH def congenital (geneics)

A

X-linked

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36
Q

PDH def tx

A

increase ketogenic nutirents (high fat content or increased lysine and leucine)

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37
Q

What are the 2 fates of pyruvate in the cytosol? (and via which enzymes/cofactors)

A

Cytosol:

Alanine

  • via alanine aminotransferase (B6)
  • carries amino groups to the liver from muscle
  • Cahill cycle

Lactate

  • via LDH (B3)
  • end step of anaerobic glycolysis
  • Cori cycle
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38
Q

What are the 2 fates of pyruvate in the mitochondria (and via which enzymes/cofactors)

A

Mitochondria:

Oxaloacetate

  • via pyruvate carboxylase (biotin)
  • addition of CO2 and ATP
  • can replenish TCA cycle or used in gluconeogenesis

Acetyl CoA

  • via PDH (B1, B2, B3, B5, lipoic acid)
  • transition from glycolisis to TCA cyle
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39
Q

where is anaerobic glycolysis major pathway (6)

A 
RBCs
Leukocytes
Kidney medulla
Lens
Cornea
Testes
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40
Q

Potassium channel position when increased glucose (…)

A

CLOSED

  • in response to increased ATP (from glucose met)
  • -> depolarization –> open Ca channels–> exocytosis)
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41
Q

B6 deficiency: impairments in what conversion of pyruvate

A

pyruvate –> oxaloacetate

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42
Q

Biotin (B6) - roles

A
  • CO2 carrier on carboxylase (e.g. pyruvatec carboxylase)
  • decarboxylase rxs
  • glycogen phosphorylase
  • transamination (ALT, AST)
  • conversion of aa precursors
    (histamine, serotonin, epi, NE, DA, GABA)
  • synthesis of cystathionine, heme, niacin
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43
Q

Enzyme directly responsible for early lens opacities

A

Aldose reductase

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44
Q

insulin receptor cascade

A

tyrosine kinase –>
phosphorylation of insulin receptor substates–>
activation of protein phosphatase –>

(1) dephosphorylates glycogen synthase –>
(glycogen synthase activated) –>
increase glycogen synthesis

(2) dephosphorylates F-1,6-biphosphatase –>
(inactivated) –>
inhibids gluconeogenesis

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45
Q

JAK protein kinase

A

second messenger system for peptide hormones such as some cytokines in JAK-STAT pathway (signal transducers and activators of transcription)

has tyrosine kinase activity; receptor does NOT have INTRINSIC tyrosine-kinase activity - i.e. - tyrosine-kinase ASSOCIATED receptor

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46
Q

Fuels post-absorbative

brain and muscles/other tissues

A

All: glucose

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47
Q

When does gluconeogenesis begin?
When is it fully active?
(hrs after last meal)

A

4-6 hrs - begins

10-18 hrs - fully active (glycogen depleted)

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48
Q

Glycogen depleted (hrs)

A

10-18 hrs

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49
Q

Fuel 24 hrs after last meal

A

Brain:
glucose

Muscles/other tissues:
FA
(some glucose)

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50
Q

Fuel 48 hrs after last meal

A

Brain:
glucose
(some ketone bodies)

Muscles/other tissues:
FA
(some ketone bodies)

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51
Q

Fuel 5 days after last meal (prolonged starvation)

A

Brain:
ketone bodies

Muscles/other tissues:
FA
(some ketone bodies and a little glucose)

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52
Q

Overnight fast-

what percentage of energy comes from glucose and from ketone bodies

A

Overnight:

90% glucose (2/3 gycogen, 1/3 gluconeogenesis)

5% ketone bodies

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53
Q

3 day fast-

what percentage of energy comes from glucose and from ketone bodies

A

3 day fast:

60% ketone bodies (1/2 beta-hydroxybutyrate, 1/2 acetoacetate)

40% glucose (gluconeogen)

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54
Q

What metabolic scenario favors synth of ketone bodies

A

production of acetyl CoA from B-oxidation
exceeds
oxidative capacity of the TCA cycle

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55
Q

What cells cannot use ketone bodies

A

RBCs

- can only use glucose

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56
Q

Primary energy source in a pt that has not eaten in two days

A

FAs

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57
Q

Rate limiting step of ketone body synth

A

HMG CoA Synthase

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58
Q

Etoh –> hypoglycemia

A
  • etoh metab increases NADH
  • pyruvate –> lactate and oxaloacetate –> malate used to regenerate NAD+
  • depleted substates for gluconeogenesis
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59
Q

insulin receptor structure

A

tetramer:
2 alpha - extracellular binding
2 beta - intracellular signalling (contain tyrosine kinase domains)

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60
Q

TNF alpha insulin resistance mech

A

TNF alpha activates serine kinases –>
1) phosphorylate IRS-1 serine residues –>
inhibits IRS-1 tyrosine phosphorylation by insulin
2) phosphorylates serine residues in beta subunit of insulin

note: phosphorylation of threonine resides has similar effects

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61
Q

What increases insulin resistance via phosphorylation of serine or threonine residues

A 
TNF-alpha
catecholamines
glucocorticoids
glucagon
(maybe intracellular FFAs)
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62
Q

NE –> Epi

A

-PNMT
(phenylethanolamine-N-methyltransferase)

  • PNMT transcription increased by CORTISOL
  • occurs mostly in adrenal medulla (unlike DA and NE - produced in cetral and peripheral nervous system)
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63
Q

enzyme tyrosine –> DOPA

A

tyrosine hydroxylase

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64
Q

enzyme DOPA –> dopamine

A

dopamine decarboxylase

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65
Q

enzyme dopamine –> NE

A

dopamine beta-hydroxylase

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66
Q

enzyme NE –> Epi

A

PNMT

pheylethanolamine-N-methyltransferase

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67
Q

Use receptor tyrosine kinase?

Signalling pathway

A 
Growth FACTOR receptors:
- EGF
- PDGF
- FGF
(etc)

MAP-kinase
Ras

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68
Q

Use tyrosine-kinase associated receptor

Signalling pathway

A 
Receptors for:
cytokines
GH
PRL
IL-2

JAK/STAT

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69
Q

Liver enzyme - TG breakdown products –> glucose precursor

A

glycerol kinase
glycerol –> glyceral 3-phosphate

(glycerol 3-phosphate –> DHAP –> (1) glycolysis or (2) gluconeogen

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70
Q

Rate limiting step of HMP shunt (pentose phosphate pathway)

A

Glucose-6-P dehydrogenase

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71
Q

Enzyme in oxidative (irreversible) phase of HMP shunt

A

G6PD

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72
Q

Enzyme in nonoxidative (rervserible) phase of HMP shunt

A

Phosphopentose isomerase, transketolases

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73
Q

Sites of HMP shunt

A 
CYTOPLASM of
RBCs and sites of fatty acid or steroid synth:
- lactating mammary glands
- liver
- adrenal cortex
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74
Q

Purpose of HMP shunt

A
  • provide source of NADPH from G6P

- yields ribose for nucleotide sythesis and glycolitic intermediates

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75
Q

NADPH uses

A
  • synth of FA and cholesterol
  • GENERATION of oxygen free rad
  • PRODECTION of RBCs from oxygen free rad
  • cytochrome p450
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76
Q

hormones that act through g-protein receptors

A 
glucagon
TSH
PTH
LH
FSH
(all Gs (?) - work through adenylate cylcase--> cAMP --> protein kinase A)
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77
Q

alpha subunit of g-protein receptor’s response to stimulation

A

release of GDP;
binding of GTP –>
dissociation of alpha subunit

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78
Q

rate limiting step in FA degredation and where is it located

A

CAT - 1
(carnitine acyl transferase 1)
(aka carnitine palmitoyl transferase 1)

cytoplasm of mitochondria?

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79
Q

What is the shuttle in FA degredation

A

carnitine

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80
Q

What is the shuttle in FA synth

A

citrate

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81
Q

What is the rate limiting step in FA synth

A

acetyl- CoA carboxylase

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82
Q

Nonpolar, hydrophobic amino acids

A 
valine
alanine
isoleucine
methionine
phenylalanine
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83
Q

alpha helix of 20 aa

A

transmembrane region

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84
Q

aldolase B def

- what should be removed from diet

A

fructose

sucrose (fructose+glucose)

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85
Q

aldolase B def - mechanism

A

phosphate trapping in fructose 6 phosphate

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86
Q

fructose –> frucotse 1-P

A

fructokinase

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87
Q

fructose 1-P –> glyceraldehyde or DHAP

A

aldolase B

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88
Q

bypasses rate limiting step of glycolysis (PFK)

A

fructose

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89
Q

DHAP –> F-1,6-BP
and
Glyceraldehyde-3-P –> F-1.6-BP

A

Muscle:
Aldolase A

Liver:
Aldolase B

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90
Q

Aldolase B def

A

Fructose intolerance

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91
Q

Fructokinase def

A

Essential fructosuria

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92
Q

positive gibs free energy favors…

A

reactants/substrates

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93
Q

cortisol receptor location

A

cytosol

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94
Q

Mcardle disease enzyme

A

myophosphorylase (muscle glycogen phosphorylase)

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95
Q

Cori disease enzyme

A

Debranching enzyme (1-6 glucosidase)

maybe debranching enzyme transferase

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96
Q

von Gierke disease enzyme

A

Glucose-6-phosphatase

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97
Q

Pompe disease enzyme

A

Acid alpha gucosidase

acid maltase

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98
Q

mild hyperglycemia exacerbated by pregnancy (enzyme inactive)

A

glucokinase:

glucose sensor within pancreatic beta cells

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99
Q

acetoacetyl-CoA –> 3-hydroxy-3-methylglutaryl CoA

pathway

A

synthesis of cholesteral and ketone bodies

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100
Q

vomiting, lethargy, failure to thrive soon after beginning breastfeeding

A

Classic galactosemia:

galactose-1-phosphate uridyl transferase

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101
Q

infant not tracking objects; lack of social smile

enzyme def

A

galactokinase deficiency

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102
Q

Thyroid hormone receptor

A

nuclear receptor

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103
Q

Retinoids receptor location

A

nucelar receptor

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104
Q

PPAR receptor location

peroxisomal proliferating activated receptors

A

nucleus

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105
Q

FA receptor locations

A

nucleus

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106
Q

Pyruvate carboxylase

location
pathway
action

A

mitochondria
gluconeogenesis
pyruvate –> oxaloacetate

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107
Q

Ornithine transcarbamoylase

location
pathway
action

A

mitochondria
urea cycle
ornithine + carbamoyl phosphate –> citrulline

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108
Q

succinate dehdrogenase

location
pathway
action

A

mitochondria
TCA cycle
succinate–> fumarate

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109
Q

3-hydroxy-3mthyglutaryl-CoA lyase

location
pathway
action

A

(HMG CoA lyase)
mitochondria
ketogenesis from HMG CoA

(HMG CoA from degradation of leucine or synth from HMG CoA synthase)

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110
Q

removal of pitutitary –> decreased epi

what enzyme act is decreased?

A

Pheylethanolamine-N-methyltransferase (PNMT)

111
Q

allosteric activator of pyruvate carboxylase

A

Acetyl CoA

increases gluconeogenesis

112
Q

sorbitol end product

A

fructose

113
Q

glucose –> sorbitol

A

aldose reductase

NADPH –> NADP+

114
Q

sorbitol –> fructose

A

sorbitol dehydrogenase

NAD+ –> NADH

115
Q

cells with particularly active polyol pathway

A

(glucose-sorbitol-fructose)
seminal vesicles
- sperm use fructose as primary energy source

116
Q

cells with less polyol pathway ability

A

(glucose-sorbitol-fructose)

Have less sorbitol dehydrogenase:

  • retina
  • renal papilla
  • Schwann cells
117
Q

pH above pKa

A

no H

  • acids neg (eg COO- )
  • bases neutral
118
Q

pH below pKa

A

H

  • acids neutral
  • bases positive (eg NH3+)
119
Q

In fructokinase deficiency - what enzyme compensates to in fructose metabolism

A

hexokinase

fructose –> fructose 6-phosphate…. glycolysis

120
Q

defect in lipoic acid results in…

2

A
  • lactic acidosis (PDH def)
  • Maple Syrup Urine disease (branced-chain ketoacid DH)

(also alpha-KG DH def)

121
Q

biologically active form of pantothenic acid

A

coenzyme A

122
Q

TCA cycle step that requires B5

A

oxaloacetate –> citrate

B5 = coenzyme A

123
Q

CoA important in synthesis of…

A 
Vit A
Vit D
cholesterol
steroids
heme A
FAs
AAs
proteins
124
Q

How is pantothenic acid activated

A
  • actively transported into cell

- ATP dependent phosphorylations –> coA

125
Q

Niacin dependent steps in TCA cycle

A

(NADH steps)

isocitrate –> alpha-KG

alpha KG –> succinyl CoA
*requires many cofactors

malate –> oxaloacetate

126
Q

Pompe disease muscle bx

A

enlarged lysosomes containing periodic acid-Schiff (PAS) + material

127
Q

infant w/ cardiomegaly, macroglossia, profound muscular hypotonia

A

Acid maltase (alpha-glucosidase) deficieny

Pompe

128
Q

accumulation of glycogen with abnormally short outer chains

A

debranching enzyme deficiency

Cori disease

129
Q

GLUT 1

A

RBCs
BBB

basal glucose transport

130
Q

GLUT 2

A

hepatocytes
beta cells of pancreas
renal tubular cells
small intestine

regulation of insulin release

131
Q

GLUT 3

A

placenta

neurons

132
Q

GLUT 4

A

skeletal muscle
adipocytes

insulin mediated uptake

133
Q

GLUT 5

A

spermatocytes
GI tract

fructose transport

134
Q

riboflavin dependent step in TCA cycle

A

Coenzyme of succinate dehdrogenase:

succinate –> fumarate

135
Q

glossitis
cheilitis
corneal neovascularization

A

ribovlavin (B2) deficiency

136
Q

liver cells with HIGH concentration of F-2,6-BP will have LOW rate of conversion of…

A

alanine –> glucose

137
Q

Increases F6P –> F-2,6P

A

insulin

138
Q

inhibition of lactate dehydrogenase would halt glycolysis due to depletion of …

A

NAD+

139
Q

what step of glycolysis regenerates NAD+ from NADH

A

pyruvate–> lactate

140
Q

“red neurons”

description and timeframe

A

red neurons: sign of IRREVERSIBLE neuronal injury

12-48 hrs after injury

eiosinophilic cytoplasm
pyknotic nuclei
loss of nissl substance

(will fragment and be phagocytized by macrophages)

141
Q

Micorosopic/Macroscopic changes in ischemic brain tissue

timeframe, description

A

12-24 hrs
Micro: red neurons

1-4 days
Micro: necrosis and neutrophils

3-5 days
Micro: macrophages

1-2 wks
Micro: reactive gliosis, vascular proliferation around necrotic area
Macro: liquifactive necrosis - well demarcated soft area (1 wk - 1 month)

> 2 wks
Micro: glial scar
Macro: cystic area surrounded by gliosis (> 1mo)

142
Q

hepcidin –>

A

hepcidin–>
decreased ferroportin expression on basolateral surface of enterocytes—>
decreased iron secretion into circulation

143
Q

MCC of primary hemochromatosis

A

mt in HFE protein

HFE interacts with transferrin receptor to increase endocytosis of the iron-transferrin complex

this iron is added to the regulatory pool to control

mt= sensing falsley low iron levels

144
Q

holosytolic
apex
radiates to axila

A

mitral regurg

145
Q

best indicator of severity of mitral regurg

A

presence of S3

146
Q

best indicator of severity for mitral stenosis

A

S2 to opening snap interval

shorter worse - ?

147
Q

thin septate hyphae

A

(with acute angles)

Aspergillus

148
Q

Giardia

immune defect

A

IgA

149
Q

Sitting up from supine

muscles

A
  • external abd obliques
  • rectus abdominus
  • hip flexors (mainly iliospsoas)
    • -> psoas major/minor
    • -> iliacus
150
Q

superior laryngeal nerve - external branch

(innervation)

A

cricothyroid muscle

151
Q

superior laryngeal nerve - internal branch (innervation)

A

sensory innervation above vocal cords

152
Q

reccurant laryngeal nerve

innervation

A

all laryngeal muscles except cricothyroid

sensory innervation below the vocal cords

153
Q

nerve at risk by superior thyroid artery and vein

A

exterior branch of superior layrngeal

154
Q

histo of Reye

A
  • microvesicular steatosis of hepatocytes
  • NO inflammation
  • cerebral edema
155
Q

Enzyme in galactose metabolism impaired in secondary lactose intolerance

A

Beta-galactosidase

Lactose (galactosyl-beta-1,4-glucose) –> Galactose

156
Q

fates of galactose

A

G1P –> G6P –> pyruvate

UDP-galactose –> Lactose
e.g. in milk production

157
Q

where does mannose enter glycolysis

A

mannose –> mannose-6P –> fructose-6P

158
Q

where does fructose enter glycolysis

A 
fructose 
---- (fructokinase)--> 
fructose-1P 
----(Aldolase B)--> glyceraldehyde (and DHAP)
-----(Triokinase)--->
glyceraldehyde-3-phosphate
----(Aldolase A or B)-->
fructose-1,6-BP

**Enters after regulation by PFK1

159
Q

mushroom toxin

A

(amatoxins)

inhibit RNA polymerase II
–> halt mRNA synthesis

160
Q

Euk RNA polymerase i

A

ribosomal RNA

161
Q

Euk RNA polymerase II

A

messenger RNA

162
Q

Euk RNA polymerase III

A

transfer RNA

163
Q

ricin toxin

from castor oil plant ricinus

A

inhibits protein syth by cleaving the rRNA component of the 60S subunit

164
Q

Leptin sites of action

A
  • acuate nuclus of hypothal to:
  • INHIBIT prod of NPY
  • STIM prod of alpha-MSH
165
Q

lac operon - produces…

A
  • beta-galactosidase
    (lactose –> glucose + galactose)
  • permease
    (increases permeability to lactose)

(an unnecessary one - transacetylase)

166
Q

lac operon - repressor bound state

A

absent lactose

lactose binds to and releases repressor

167
Q

lac operon - state with excess glucose and excess lactose

A

nothing bound

  • repressor unbound due to lactose
  • CAP (activator) not bound due to excess glucose –> decreasing activity of adenylate cyclase –> decrease intracellular cAMP
168
Q

lac operon - control of catabolite activator protein (CAP)

A
  • inhibited by low intracellular cAMP
169
Q

Pigmented gallstones

  • enzyme
  • risks
A

infx of biliary tract –>
release of beta-glucuronidase from injured hepatocytes and bacteria—>
hydrolysis of bilirubin glucuronides—>
increase unconj bilirubin in bile

risks: 
biliary infx with 
E coli
Ascaris
Opisthrchis (liver fluke)
170
Q

common trigger for hepatic encephalopathy

A

GI bleeding

increase in ammonia and nitrogen absorption by the gut

171
Q

cells in brain affected by acute rise in ammoninia

A

astrocytes

neurons

172
Q

ammonia toxicity results from depletions of… (in the brain)
(2)

A

GLUTAMATE
- increased conversion of glutamate –> glutamine by glutamine synthetase in astrocytes (excess glutamine –> astrocyte swelling and dysfx)

ALPHA-KETOGLUTARATE
- NH4 can detoxified to glutamate with alpha-KG via glutamate dehydrogenase –> depletes alpha-KG –> impairs energy metabolism (TCA cyle)

173
Q

Lynch syndrome

genetics

A

AD

abnormal nucleotide mismatch repair

174
Q

cofactor in synthesis of delta-aminolevulinic acid

A

pyridoxal phosphate

succinyl-CoA + glycine (w/ pyridoxal phosphate)—> ALA

175
Q

ribosomal subunit fx:

- 23S

A

in 50s ribosome

- facilitate peptide bond formation (peptidyltransferase)

176
Q

ribosomal subunit fx

- 16S

A

in 30s ribosome

  • contains sequence complementary to the “Shine Dalgamo” sequence on mRNA
  • binding of these complementary sequences necessary for initiation of protein translation
177
Q

Shine Dalgamo sequence

A

in all prokaryotic mRNA

  • located ~10bp up from the AUG start codon
  • allow for binding to 16S subunit on 30S ribosome
178
Q

ApoA-1

A

LCAT activation (cholesterol esterification)

179
Q

ApoB-48

A

chylomicron assembly and secretion by the instestine

180
Q

ApoB-100

A

LDL particle uptake by extrahepatic cells

181
Q

ApoC-II

A

lipoprotein lipase activation

182
Q

ApoE-3 and 4

A

VLDL and chylomicron remnant uptake by liver cells

183
Q

Kozak consensus sequence

A

Eukaryotic mRNA
upstream from AUG (methione start)
initiator for translation (i.e. mRNA binding to ribosomes)

  • a purine (G or A) positioned 3 bases upstream from the AUG appears to be a key factor
  • mt a/w thalassemia intermedia
184
Q

Beta thalasemia mt causes…

A

defective transcription, processing, and translation of beta-globin mRNA

185
Q

Target cell ddx

A

“THAL” (or “HALT”

  • Thallasemia
  • HbC disease
  • Asplenia
  • Liver disease
186
Q

HbC and HbS electrophoresis

A

HbC will not travel as far as either normal or HbS;
HbS will not travel as far as normal

HbS
neg charged glutamate –> nonpolar valine (decreased neg charge)

HbS
neg charged glutamate –> positively charged lysine (even less neg charge)

187
Q

cyanide poisoning antitode mech

A

Nitrites:
hemoglobin (Fe2+)–> methemoglobin (Fe3+)

methemoglobin binds CN more tightly –> keeps it sequestered in blood and away from mitochondrial enzymes

188
Q

activators of ALA synthase

A

Etoh
Barbiturates (think of w/anxiety)
Hypoxia

189
Q

Repressors of ALA synthase

A

heme

glucose

190
Q

Acute Intermittent Porphyria

symptoms

A 
5 P's:
Painful abdomen
Port wine urine
Polyneuropathy
Psychological disturbances
Precipitated by drugs*
Barbituates
Seizure drugs
Rifampin
Metoclopromide
Etoh
griseofulvin
phenytoin

(also stavation)

191
Q

Acute intermittent porphyria tx

A

heme and glucose –> block ALA synthase

192
Q

Enzyme- acute intermittent porphyria

A

Porphobilinogen deaminase

193
Q

Enzyme - porphyria cutanea tarda

A

uroporphyrinogen decarboxylase

194
Q

Enzyme - lead poisoning

A

ALA dehydratase

Ferrochelatase

195
Q

triggers for sickle cell aggregation

A

hypoxia
low pH
high 2,3DPG

196
Q

heme –> biliverdin

enzyme

A

Heme oxygenase

197
Q

glutamate residue carboxylation in liver

vitamin

A

K

essential for some clotting factor production

198
Q

Active or passive:

1) liver uptake of unconj bili
2) liver excretion of conj bili

A

1) passive uptake
2) active secretion into bile canniculi*

passive diffusion via baolateral OATP allows conj bili to leak into blood stream

199
Q

Crigler Najal

enzyme

A

UDP-glucuronyl transferase

  • absent

(conjugation of bili)

200
Q

Gilbert syndrome

enzyme

A

UDP-glucuronyl transferase

  • low

(conj of bili)

201
Q

Defect in secretion of bile

A

Dubin- Johnson

Rotor

202
Q

Stop codons

A

UGA
UAA
UAG

“U Go Away”
“U Are Away”
“U Are Gone”

203
Q

spoon nails + dysphagia

A

Fe deficiency

204
Q

Anemia:
PO2
% Saturation
O2 content

A

pO2: normal
sat: normal
O2 content: low

205
Q 
after beginning chemo:
hyperphosphatemia
hypocalcemia
hyperkalemia
hyperuricmia

dx and tx

A

tumor lysis syndrome

tx (prevention):
hydration + hypouricemic agents (allopurinol or rasburicase)

206
Q

Rasburicase

MOA

A

recombinant urate oxidase

uric acid –> allantoin (more soluble than uric acid)

207
Q

chemo –> cardiotoxicity

drug and prevention

A

Drug:
doxurubicin
daunorubicin

Prevent:
dexrazone

*trastuzumam (herceptin) also causes cardiotoxicity

208
Q

chemo –> myelosuppression

2

A

Drug:
methotrexate

Prevent:
leukovorin (folinic acid)

Drug:
5-FU

Prevent:
uridine

209
Q

chemo –> hemorrhagic cystitis

A

Drug: cyclophosphamide

Prevent:
mesna

210
Q

Give dexrazene with ___ to prevent _____

A

with: doxurubincin/daunorubicin

to prevent:
cardiotxicity

211
Q

Give leukovorin with ___ to prevent_____

A

with:
methotrexate

to prevent:
myelosuppression

212
Q

Give mesna with ___ to prevent ____

A

with:
cyclophosphamide

to prevent: hemorrhagic cystitis

213
Q

Give uridine with ____ to prevent ____

A

with:
5-FU

to prevent:
myelosuppression

214
Q
  • exertional dyspnea
  • pneumonia (–> life threatening acute chest syndrome)
  • recurrent abdominal and bone pain
A

Sickle cell

glutamic acid –> valine

215
Q

G6PD action

A

GDPD –> 6-phosphogluconate

*rate limiting step in HMG/pentose phosphate shunt

216
Q

G6PD deficiency genetics

A

X-linked

217
Q

G6PD necessary for:

A

HMP (pentose phosphate) shunt:

  • produce NADPH
  • produce ribulose-5-phosphate
218
Q

mt in JAK2

3 blood d/o

A

-essential thrombocytosis
(hemorrhagic and thrombotic symptoms)

-polycythemia vera
(pruritis, splenomegaly, thrombotic cx)

  • primary myelofibrosis
    (severe fatigue, splenomegaly often causing early satiety, hepatomegaly, anemia, bone marrow fibrosis)
219
Q

Primary myelofibrosis smear

A

teardrop (dacrocytes)

nucleated RBCs

220
Q

bisphosphoglycerate mutase

A

1,3BPG –> 2,3BPG

*consumes energy that would have otherwise been used to produce energy in the form of ATP
(alternate glycolytic pathway)

221
Q

pyruvate kinase deficiency

A 
[phosphoenolpyruvate --> pyrvate)
def --> hemolytic anemia due to failure of glycolysis

–> splenic hypertrophy due to increased work of removing deformed erythrocytes

222
Q

Haldane effect

A

binding of O2 drives release of H+ and CO2 from hemeoglobin

223
Q

Bohr effect

A

high CO2 and H+ facilitate O2 unloading from Hb

224
Q

xeroderma pigmentosum

enzyme; genetics

A

AR

endonuclease - nucleotide excision repair enzyme
UV-specific endonuclease

225
Q

Fructose -6P –> ribose

enzymes- 2

A

transaldolase
transketolase

(non-ox/reversible reactions of the HMP shunt)

*all cells

226
Q

radiation (tx) mech

A

1) DNA double strand breaks

2) formation of free radicals (reactive oxygen species from ionization of water)

227
Q

RBCs unable to synth heme b/c of lack of…

A

mitochondria

necessary for first and final three steps

228
Q

mTOR pathway

A

growth factor binds to rec tyrosine kinase

  • -> activate phosphoinositide 3-kinase (PI3K)
  • -> phospholylates PIP2 to PIP3 (in plasma membrane)
  • -> activate protein kinase B (Akt) - a serine/threonin specific kinase
  • ->activates mTOR
  • ->mTOR translocates to nucleus
  • -> induce genes for survival, anti-apoptosis, angiogenesis

*inhibitied by PTEN, a tumor suppressor proetin that removes phosphate from PIP3

229
Q

Why is HCV genetically unstable

A
  • it’s RNA polymerase lacks proofreading 3’–>5’ exonuclease

- envelope glycoprotein contains a hypervariable region prone to mt

230
Q

Alkaptonuria

A

AR
homogentisate oxide def
- step in tyrosine –> fumarate

  • dark connective tissue
  • brown sclerae
  • urine turns black on prolonged exposure to air
    may have debilitating arthralgias (homogentisic acid toxic to cartilage)
231
Q

increased glycogenolysis in muscles (mech)

A

increased calcium in cytosol

  • ->allosterically activates phosphorylase kinase
  • -> phosphorylates (activates) muscle phosphorylase
  • -> —> glycogen breakdown
232
Q

additions or deletions of a number of base not in a multiple of 3

A

framshift

233
Q

MC cystic fibrosis mt mech

A

codon deletion of phenylalanine

234
Q

Antibodies w/ high specificity for rheumatoid arthritis

A

anti-citrulinated peptide

anti-CCP

235
Q

main amino acids in elastin

A

glycine
alanine
valine
(all non-polar)

also contains proline and lysine but most are not hydroxylated (unlike collagen)

236
Q

what accounts for elastin’s resilance

A

extensive desmosine crosslinking
(interchain crosslinks involving 4 different lysines on 4 elastin chains)

extracellualar lysyl hydroxylase does crosslinking

237
Q 
severe abdominal pain
hypotension
hyperventilate
met acidosis
increased AG
high plasma lactate

what enzyme has low activity

A

pyruvate dehydrogenase
(oxidative phosphorylation pathway)

(this is hypoxia-induced lactic acidosis)

238
Q

what about the desired gene do you need to know to do pcr

A

the nucleotide sequence of the regions flanking the target DNA

239
Q

fibrillin

A

major component of the microfibrils that form a sheath around elastin fibers

acts as an extracellular scaffold for deposition of elastin extruded from connective tissue cells

abundant in blood vessels, periosteum, and suspensory ligaments of the lens

240
Q

glycoprotein from viral sythesis that forms spheres and tubules and poorly correlates with viral replication

A

an envelope component of HBV
(HBsAg)

often made in large excess

241
Q

location of collagen hydroxylation of proline/lysine

requires vit C

A

RER

242
Q

most abundant protein in the human body

A

collagen

243
Q

most abundant amino acid in collagen molecule

A

glycine

at LEAST every 3rd amino acid

244
Q

defects in ubiquitin-proteasome system can lead to what neurodegen d/os

A

Parkinson

Alzheimer

245
Q

PKU tx with tyrosine –> normal serum phenylalanine but elevated PRL

what enzyme is def

A

Dihydrobiopterin reductase

246
Q

Tetrahydrobipterin (BH4) cofactor in…

A

phenylalanine –> tyrosine
tyrosine—>DOPA

synth of serotonin
synth of NO

247
Q

Alanine –> ?
Aspartate –> ?
via alpha-KG transamination

A

alanine –> pyruvate

aspartate –> oxaloacetate

248
Q

cofactor for transamination

A

B6

249
Q

major transporter of nitrogen to the liver for disposal

A

alanine

250
Q

what carries nitrogen to the kidneys from most tissues

A

glutamine

glutamine
—(glutaminase)—>
glutamate + NH3

251
Q

Vit A tox

A

intracranial htn
skin changes
hepatosplenomegaly
hyperlipidemia

acute:
n/v
vertigo
blurred vision

252
Q

N-acetylglutamate

- activator of _____ in NH3 exretion

A

carbomoyl phosphate synthase 1

CO2 + NH3 –> carbomoyl phssphate
entry into the urea cycle

253
Q

amino group of what aa directly provides N for the urea cycle

A

aspartate

254
Q

megoloblastic anemia
neuro abnl
growth retardation
orotic acid in urine

A

orotic aciduria (AR):

defect in UMP synthase (pyrimidine synth pathway)

unable to convert orotic acid –> UMP

supplement with uridine monophosphate

NB: NORMAL ammonia (vs ornthine transcarbamylase def)

255
Q

ornithine transcarbamylase def

A

XR
defect in urea cycle

  • increased orotic acid in blood and urine
  • HIGH ammonia in blood
  • low BUN
  • NO megaloblastic anemia
tx: 
decrease protein
phenylbuterate
benzoate
biotin
256
Q

enzymes that use B1

A

pyruvate dehydrogenase
alpha-KG dehydrogenase
transketolase

257
Q

foamy histiocytes

A

Niemann-Pick

sphyngomyelin accumulates in histiocytes

258
Q

metabolism of very long chain fatty acids or fatty acids with branch points at odd numbers

A

peroxisomes

  • VLCFA –> special form of beta ox
  • branched chain (e.g. phytanic acid) –> alpha ox
259
Q

peroxisome defects lead to

A

neuro deficits from improper CNS myelination

260
Q

young
spastic paresis of LE and choreoathetoid movements
high arginine

enzyme

A

arginase

last step in urea cycle

261
Q

phenylalanine derivatives

A

phenylalanine —>

–[BH4]–>tyrosine
( also tyrosine—> thyroxine)

–[BH4]–>Dopa
( also Dopa—>Melanin)

  • -[B6]-> Dopamine
  • -[vit C]-> NE
  • -[SAM]-> Epi
262
Q

Tryptophan derivatives

A

tryptophan
–[B6]–> Niacin

tyrptophan

  • -[B6, BH4]–> serotonin
  • –> melatonin
263
Q

Histadine derivatives

A

histadine

–[B6]–> histamine

264
Q

Glycine derivatives

A

glycine

  • -[B6]–> porphyrin
  • –> heme
265
Q

Glutamate dervivatives

A

glutamate
–[B6]–> GABA

glutamate
—> glutathione

266
Q

Arginine derivatives

A

arginine
—> creatine

arginine
—> urea

argininine
–[BH4]–> Nitric Oxide

267
Q

transamination reaction (vit)

A

B6

pyridoxal phosphate

268
Q 
met acidosis
large AG
ketosis
hypoglycemia
high methylmalonic acid

deficient reaction

A

Isomerization

methylmalonyl CoA –> Succinyl CoA

(this is methylmalonic acidemia)

269
Q

what amino acids should be avoided in Maple Syrup Urine Disease

A

(branched chain)
leucine
isoleucine
valine

270
Q

principal stabilizing force for secondary structure of proteins

A

H bonds

271
Q

cofactors for branched chain alpha-ketoacid dehydrogenases

A

(like PDH and alpha-KG DH)

TLC For Nobody
thiamine
lipoic acid
coenzyme A
FAD
NAD
272
Q

Maple Syrup Urine Disease enzyme

A

branched chain alpha-ketoacid-dehydrogenase

273
Q

Propionyl CoA

comes from….

A 
- AAs:
Threonine
Methionine
Valine
Isoleucine
  • odd-numbered FAs
  • cholesterol side chains

Uworld (9 decks)

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