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1
Q

How can we differentiate Neimann Pick from Tay Sachs?

A

Both have cherry red spot

Neimann Pick has HSM (sphingomyelin builds up in lipid-laden foam cells that accumulate), Tay Sachs does not

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2
Q

Enzyme deficient in metachromatic leukodystrophy?

A

Arylsulfatase A deficiency

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3
Q

Findings in metachromatic leukodystrophY?

A

CNS accumulation of cerebroside sulfate –> Central and peripheral demyelination

Peripheral neuropathy and ataxia

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4
Q

Enzyme deficient in Krabbe’s disease?

A

galactocerebrosidase

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5
Q

How does Krabbe’s disease present?

A

Developmental delay and/or regression, hypotonia, optic atrophy, and seizures

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6
Q

What accumulates in Fabry disease?

A

Alpha-galactosidase A deficiency –> build up of ceramide trihexoside

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7
Q

What is the first step in heme synthesis?

A

Succinyl CoA and glycine — (ALA synthase) —> ALA

ALA = alpha amino levulinic acid

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8
Q

Which two enzymes in the heme synthesis pathway are inhibited by lead?

A 
ALA dehydratase (ALA --> porphobilinogen, PBG)
Ferrochelatase (portophyrin IX + Fe2+ --> heme)
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9
Q

What builds up with lead poisoning?

A

ALA

Zinc portophyrin IX (combines with zinc instead of lead)

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10
Q

Which enzyme is deficient in acute intermittent porphyria?

A

Porphobilinogen deaminase (PBG deaminase)

Characterized by acute attacks of abdominal pain, neuropsychiatric symptoms, and red or brown urine

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11
Q

What are the symptoms associated with porphyria cutanea tarda? What enzyme is most commonly affected?

A

Urophorphyrinogen decarboxylase

Leads to blisters where skin was exposed

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12
Q

Which porphyrin precursor products lead to photosensitivity?

A

Late ones- they must be a porphyrinogens or porphyrins

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13
Q

Which vitamins is a cofactor for ALA synthase?

A

Pyridoxal phosphate- B6

B6 deficiencies can lead to a microcytic hypochromic anemia

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14
Q

What are the effects of Pompe’s disease on the heart?

A

Cardiomegaly

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15
Q

What are the two galactokinase deficiencies and which one is worse?

A

Galactokinase deficiency–> less common, only leads to cataracts

GALT (galactose-1-phosphate uridyl transferase) deficiency –> vomiting, jaundice, hepatomegaly, lethargy

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16
Q

Most common cause of cystic fibrosis?

A

delta F508 –> misfolded protein

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17
Q

What is the copper reduction test?

A

Nonspecifically detects the presence of reducing sugars in the urine (fructose, glucose, or galactose)

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18
Q

What is the toxic build up in aldolase B deficiency and what is the consequence?

A

Toxic build up of fructokinase-1-phosphate, which builds up in the liver

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19
Q

What is the point of the 5’ –> 3’ exonuclease activity of bacterial DNA polymerase I?

A

Removed the RNA primer created by RNA primase and repair damaged DNA sequences

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20
Q

How does a B12 deficiency lead to impaired myelination?

A

Subacute combined degeneration

B12 is required for methylmalonyl CoA mutase. When it is impaired, methylmalonyl CoA cannot be converted to succinyl CoA, and its precursor, methylmalonic acid, builds up and impairs myelin synthesis

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21
Q

What reaction in the DNA synthesis pathway requires B12?

A

RBC synthesis depends on B12-dependent recycling of folate

Conversion of homocysteine to methionine with methionine synthase

This reaction creates THF, which is required for DNA synthesis

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22
Q

Connect PRPP synthetase deficiency to gout

A

Deficiency leads to increased production of purines and consequently increased purines precipitate as gout

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23
Q

Describe the use of colchicine in the acute management of gout?

A

Colchicine is useful in the acute management of gout when NSAIDS are contraindicated. It inhibits neutrophil chemotaxis and phagocytosis by inhibiting microtubule formation

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24
Q

Other than reducing oxidizing glutathione, what other biochemical process is NADPH required for?

A

Cholesterol and fatty acid synthesis

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25
Q

Describe the activation and inhibition of lipolysis of triglycerides in adipose tissue

A

Stress hormones stimulated Gs –> increased cAMP and activated PKA to activate hormone sensitive lipase which released free fatty acids.

HSL is inhibited by insulin

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26
Q

What is the embryologic purpose of the vitelline (omphalomesenteric) duct?

A

connects midgut lumen to the yolk sac

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27
Q

Structural derivatives of pharyngeal pouches 1-4?

A

1- Ear stuff
2- epithelium of palatine tonsil crypts
3- thymus, inferior parathyroid glands
4- Superior parathyroid glands,

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28
Q

Tx for homocystinuria?

A

B6 administration

Dietary methionine restriction and cysteine supplimentation

29
Q

Chediak-Higashi syndrome?

A

Immunodeficiency, albinism, neurologic defects (like nystagmus)

ID comes from inhibition of phagolysosome fusion in neutrophils

AR inherited condition

30
Q

Which embryologic layer gives rise to the anterior pituitary?

A

Surface ectoderm

31
Q

What is the role of IL-3 (secreted by activated T cells?)

A

Stimulates growth and differentiation of stem cells from bone marrow

32
Q

Mutation in primary myelofibrosis?

A

JAK2- a cytoplasmic tyrosine kinase –> constitutive JAK/STAT activation

All chronic myeloproliferative disorders have this mutation (polycythemia vera, essential thrombocytosis, primary myelofibrosis)

33
Q

What are the serum and urine levels of calcium seen with calcium stones?

A

Normocalcemic plasma levels - regulated by Vit D, calcitonin and PTH

Hypercalciuria - idiopathic usually

34
Q

Both thyroid parafollicular cells and chromaffin cells of adrenal medulla are derived from which embryological layer?

A

Neural crest

35
Q

Structures arising from neural crest?

A

MOTEL PASS

Melanocytes
Odontoblasts
Tracheal cartilage
Enterochromaffin cells
Laryngeal cartilage
Parafollicular cells of thyroid
Adrenal medulla
Schwann cells
Spiral membrane
36
Q

What is MELAS?

A

Mitochondrial encephalomyelopathy with lactic acidosis and stroke-like episodes

37
Q

Describe psychologic “reaction formation”

A

Uncomfortable feelings are transformed into their opposite

38
Q

How does ionizing radiation kill cells?

A

dsDNA breaks, free radical formation

39
Q

How does non-ionizing radiation (UV light) cause DNA damage?

A

Formation of pyrimidine-pyrimidine (thymine) dimers

40
Q

CD14 is a marker for which type of cell?

A

Macrophage

41
Q

What CSF level is low in narcolepsy?

A

Hypocretin-1

42
Q

Function of smooth ER?

A

Lipid synthesis, Carbohydrate metabolism, detox of harmful substances

SEx steroid synthesis

43
Q

Succinate dehydrogenase requires which cofactor?

A

B2- riboflavin

succinate –> fumarate

44
Q

How does the valsalva maneuver help with paroxysmal supraventricular tachycardia?

A

STimulates vagal tone –> decreases heart rate

45
Q

Describe potassium levels during DKA

A

Overall, total body K+ is low (K+ is lost in the urine, hypovolemia –> increase in aldosterone and consequent loss of K+)

Despite low K+ levels overall, K+ is normal or increased in the blood b/c movement across concentration gradient, lack of insulin causes shift outside

Insulin normally promotes cellular uptake of insulin

46
Q

What causes a type II (Beta) error?

A

Low power study

–> Falsely concludes there is no significant difference when there is

47
Q

What is type I (alpha) error?

A

Falsely concludes there is a significant difference when there is not

48
Q

What is Berkson’s bias?

A

Bias created when you choose hospitalized patients as the control group

49
Q

What is open angle glaucoma?

A

Increased intraocular pressure due to increased aqueous humor production or decreased outflow

50
Q

One advantage of the live polio vaccine is that it increases production of what Ig?

A

DUODENAL IgA

Secretory IgA is the major antibody associated with mucosal immunity

51
Q

Which amino acid is elevated in astrocytes with hepatic encephalopathy?

A

Glutamine

Elevated ammonia –> increased production of glutamine to help it get excreted in the urea cycle.

52
Q

Ankle sprains usually involve which ligament?

A

Anterior talofibular ligament

53
Q

Mastocytosis can lead to what abnormality in the stomach?

A

Increased gastric secretion of HCl due to excess histamine stimulation of parietal cells

54
Q

How does aminoglycoside resistance develop?

A

Bacterial production of aminoglycoside-modifying enzymes that transfer different chemical groups to the antibiotic molecule thereby decreasing its ability to bind the ribosome at 30S

55
Q

Differentiate the build up of conjugated vs unconjugated bilirubin in Gilbert’s vs dubin johnson syndrome

A

Dubin Johnson- build up of conjugated bilirubin

Gilbert’s - build up of unconjugated

56
Q

Delayed type (IV) hypersensitivity is characterized by what histologic changes of the skin?

A

spongiosis and accumulation of edema fluid in the intercellular spaces

57
Q

Most common cause of fetal unilateral hydronephrosis?

A

UPJ obstruction- failure of canalization

58
Q

Differentiate structures that arise from the metanephric blastema vs ureteric bud

A

Metanephric- glomeruli, bowmans space, nephron through the distal convoluted tuble

Ureteric bud: Collecting tubules –> ureters

59
Q

What part of the tRNA binds to the ribosome?

A

The T-loop (left loop) that contains those weird amino acids

60
Q

What does desmolase do?

A

Conversion of cholesterol to pregnenolone

61
Q

What is the MOA of amatoxins from mushrooms?

A

Binding to DNA-dependent RNA polymerase II and therefore halting mRNA synthesis

62
Q

MOA of ricin?

A

Inhibits protein synthesis by cleaving rRNA component of eukaryotic 60S subunit

63
Q

How does fructose enter the glycolytic pathway in people with benign hereditary fructosuria?

A

Hexokinase converts fructose to fructose 6-phosphate, which can then enter glycolysis

64
Q

What is the enzyme deficient when beta-oxidation is impaired?

A

Acyl-CoA dehydrogenase

65
Q

Explain Hartnup disease

A

Deficiency in the ability to absorb neutral amino acids in the small intestine and proximal tubule of the kidney –> eventual niacin deficiency (from tryptophan)

–> pellegra like symptoms (with skin rashes) and cerebellar ataxia

66
Q

List reaction sequences that require BH4

A

Phenylalanine –> tyrosine –> DOPA ….

Tryptophan –> serotonin …

67
Q

G energy in protein, carbs, fats and ethanol?

A

Protein and carbs: 4g
Fats: 9g
Ethanol: 7g

68
Q

Where in the cell does the hydroxylation of proline and lysine for collagen synthesis occur?

A

Inside the rough endoplasmic reticulum

69
Q

Which reaction in the TCA generates GTP?

A

Succinyl-CoA to succinate (by succinyl-CoA synthase)

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