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Biochemistry > Metabolic Pathways Physiology and Pathology > Flashcards

Metabolic Pathways Physiology and Pathology Flashcards

1
Q

Presentation of homocystinuria

A

1) Ectopia lentis
2) Mental retardation
3) Marfanoid habitus
4) Osteoporosis
5) Increased homocysteine in urine

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2
Q

Mental retardation, eczema, and a mousy, must body odor; autosomal recessive

A

Phenylketonuria (PKU)

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3
Q

Infant with vomiting, lethargy and odor of burnt sugar in diapers; occurs several days after birth; acidosis

A

Maple syrup urine syndrome

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4
Q

Defective breakdown of the branched chain amino acids leucine, isoleucine, and valine; results in increased alpha keto acid; due to defect in alpha ketoacid dehydrogenase

A

Maple syrup urine syndrome

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5
Q

What is the defective enzyme in maple syrup urine syndrome?

A

1) alpha keto acid dehydrogenase

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6
Q

Sphingomyelinase deficiency. What is the disease? What substrate accumulates?

A

1) Niemann-Pick disease (autosomal recessive)

2) Sphingomyelin

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7
Q

What are clinical findings of Niemann-Pick disease?

A

1) Neurodegeneration
2) Hepatosplenomegally
3) Cherry red spot on macula
4) Foam cells

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8
Q

Deficiency in alpha galactosidase A. What is the disease? What substrate accumulates?

A

Think: fAbry = galactosidase A!

1) Fabry’s disease (X linked recessive)
2) Ceramide trihexoside

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9
Q

What are findings of Fabry’s disease?

A

Think: Fabry can Feel his Feet

1) Peripheral neuropathy of the hands and feet
2) Cardiovascular and renal disease
3) Clouded corneas
4) Multiple small, red, raised papules around umbilicus and thighs
5) Decreased ability to sweat (hypohidrosis)

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10
Q

Deficiency of Glucocerebrosidase. What is the disease? What substrate accumulates?

A

1) Gaucher’s disease (autosomal recessive)

2) Glucocerebroside

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11
Q

Deficiency in hexosamindidase A. What is the disease? What is the substrate that accumulates?

A

Think: heXosamindidase A = tay-saXs

1) Tay-Sach’s disease (autosomal recessive)
2) GM2 ganglioside

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12
Q

What are findings in Tay-Sach’s disease

A

1) Developmental delay
2) Cherry red spot on macula
3) Lysosomes with onion skin
4) No hepatosplenomegally

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13
Q

How do you differentiate between Tay-Sach’s disease and Neiman-Pick disease?

A

1) Both have cherry red spot on macula

2) Neiman-Pick disease has hepatosplenomegally

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14
Q

Deficiency in galactocerebrosidase. What is the disease? What substrate accumulates?

A

1) Krabbe disease (autosomal recessive)

2) Galactocerebroside

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15
Q

Deficiency in Arylsulfatase A. What is the disease? What substrate accumulates?

A

1) Metachromatic leukodystrophy

2) Cerebroside sulfate

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16
Q

What are findings of a pt. with Gaucher’s disease?

A

1) Hepatosplenomegally
2) Aseptic necrosis of femur
3) Bone crises (Thrombocytopenia, Leukopenia, ect.)
4) Gaucher cells (macrophages that look like tissue paper)

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17
Q

3 yr old presents with severe intelectual disability. Musty body odor. He dies 6 months later from refractory seizures; autopsy shows pallor of the substantia nigra, locus ceruleus. What is the underlying condition? What is the cause?

A

1) Phenylketonuria

2) Absence of phenyalanine hydroxylase to convert phenyalanine to tyrosine

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18
Q

Vitamin A deficiency results in?

A

1) Night blindness

2) Dry skin

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19
Q

Vitamin A toxicity results in?

A

1) Arthalgias
2) Fatigue
3) Headaches
4) Teratogenic (cleft lip palate and heart defects)

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20
Q

Function of Thiamine (B1)

A

1) Thiamine Pyrophosphate (TPP) is a cofactor for decarboxylation
Think: ATP
- Alpha ketoglutatrate and Alpha ketoacid dehydrogenase
- Transketolase (pentose phosphate pathway)
- Pyruvate dehydrogenase

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21
Q

What tissues are affected first in a Vitamin B1 deficiency

A

1) Brain (Dry beriberi)

2) Heart- dilated cardiomyopathy (wet beriberi)

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22
Q

Function of Riboflavin (B2)

A

1) Cofactor for oxidation and reduction (FAD and FMN = 2 ATP)

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23
Q

What does a vitamin B2 (riboflavin) deficiency result in?

A

Think: 2 Cs of B2

1) Cheliosis
2) Corneal vascularization

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24
Q

Function of vitamin B3 (niacin)

A

1) Constituent of NAD and NADP (B3 = 3 ATP)

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25
Q

What does a vitamin B3 (niacin) deficiency result in?

A

Pellagra

1) Dementia
2) Dermatitis
3) Diarrhea

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26
Q

Function of Vitamin B5 (Pantothenate)

A

Think: pentothenate

1) Essential component for CoA and fatty acid synthase

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27
Q

What can induce vitamin B6 deficiency?

A

Isoniazid and oral contraceptives

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28
Q

What is the function of vitamin B7 (biotin)?

A

1) Carboxylation

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29
Q

What binds to biotin?

A

Think: Avidin in egg whites AVIDly binds biotin

1) Avidin

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30
Q

How do you differentiate between a folate and a B12 deficiency?

A

1) Folate has no neurologic symptoms

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31
Q

What has a longer storage reserve? Folate or B12?

A

B12 - it can last for several months

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32
Q

Function of B12

A

1) Co factor for homocysteine methyltransferase ( involved with formation of THF)
2) Cofactor for methylmalonyl CoA mutase (involved with hemoglobin formation)

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33
Q

Deficiency of B12 results in?

A

1) Megaloblastic anemia
2) Hypersegmented neutrophils
3) Ascending and descending degradation of spinal tracts

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34
Q

What enzyme requires regeneration of methionine and thus dependent upon vitamin B12?

A

1) S- adenosyl methionine (SAM)

Think: SAM is the methyl donor man

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35
Q

What is S-adenosyl methionine (SAM) required for?

A

1) Conversion of NE to epinephrine

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36
Q

What is the only common cause of excess vitamin D?

A

Sarcoidosis

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37
Q

What is the rate limiting step in the urea cycle?

A

1) Formation of carbamoyl phosphate from CO2, ammonia, and ATP
2) Catalyzed by carbamoyl phosphate synthase

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38
Q

What is required for citurline to be formed in the urea cycle?

A

1) Carbamoyl phosphate must combined with ornithine

2) Catalyzed by ornithine transcarbamoylase

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39
Q

What does citurline become in the urea cycle?

A

1) Citurline becomes Arginosuccinate in the cytoplasm

2) Catalyzed by Argininosuccintate synthase

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40
Q

Where is urea formed in the urea cycle?

A

1) In the conversion of Arginine to Ornithine

2) Catalyzed by arginase

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41
Q

What occurs if there is impairment to the urea cycle?

A

1) Pt. have neurological damage due to increased serum ammonia levels

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42
Q

What enzyme is key in the formation of citruline? If deficient in this enzyme what is the mode of inheritance?

A

1) Ornithine transcarbamoylase

2) X linked deficiency

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43
Q

What cofactors does Pyruvate dehydrogenase and the alpha ketoglutarate dehydrogenase complex require?

A

Think: 1,2,3, four, 5 Lipo

1) Thiamine
2) FAD
3) NAD
4) CoA
5) Lipoic acid

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44
Q

Where is lipoic acid used as a cofactor?

A

1) Pyruvate dehydrogenase

2) alpha ketoglutarate dehydrogenase complex

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45
Q

Where does ethanol metabolism take place in cells?

A

1) Cytoplasm (alcohol dehydrogenase converts ethanol to acetaldehyde)
2) Mitochondria (acetaldehyde is converted to acetate by acetaldehyde dehydrogenase)

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46
Q

What drug inhibits alcohol dehydrogenase?

A

1) Fomepizole

2) Important when methanol intoxication occurs

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47
Q

What drug inhibits acetaldehyde dehydrogenase

A

1) Disulfiram

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48
Q

Protein malnutrition resulting in skin lesions, edema, liver malfunction

A

Kwashiorkor

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49
Q

Energy malnutrition resulting in tissue and muscle wasting

A

Think: Marasmus results in Muscle wasting

1) Marasmus

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50
Q

What metabolic pathways work in both the cytoplasm and the mitochondria?

A

Think: HUGs take Two

1) Heme synthesis
2) Urea cycle
3) Gluconeogenesis

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51
Q

Enzyme of Rate limiting step for glycolysis?

A

Phosphofructokinase-1 (PFK-1)

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52
Q

Enzyme of Rate limiting step for gluconeogenesis?

A

Fructose 1,6 bisphosphatase

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53
Q

Enzyme of Rate limiting step for TCA cycle?

A

Isocitrate dehydrogenase

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54
Q

Enzyme of Rate limiting step for glycogen synthesis

A

Glycogensynthase

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55
Q

Enzyme of rate limiting step for glycogenolysis

A

Glycogen phosphorylase

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56
Q

Enzyme of rate limiting step for HMP shunt

A

Glucose 6 phosphate dehydrogenase

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57
Q

Enzyme of rate limiting step for de novo pyrimidine synthesis

A

Carbamoyl phosphate synthetase

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58
Q

Enzyme of rate limiting step for de novo purine synthesis

A

Glutamine PRPP amidotransferase

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59
Q

Enzyme of rate limiting step for urea cycle

A

Carbamoyl phosphate synthetase

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60
Q

Enzyme of rate limiting step for ketogenesis

A

HMG CoA synthase

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61
Q

Enzyme of rate limiting step for cholesterol synthesis

A

HMG CoA reducase

target of statin drugs

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62
Q

What two lysosomal storage diseases causes a cherry red spot on the macula? How do you differentiate them?

A

1) Niemann-Pick disease and Tay-Sachs disease

2) Niemann-Pick has hepatosplenomegally

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63
Q

Function of glucokinase/hexokinase? What is the difference between these two enzymes?

A

1) Glucose –> Glucose 6 phosphate
2) Glucokinase (low affinity, high capacity/Vmax) found in liver and beta cell of pancreas; influenced to induce by insulin
3) Hexokinase (High affinity, low capacity) unaffected by insulin

Think: Glucokinase is a Glutton, He is never satisfied
.0

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64
Q

What is active at low glucose concentrations? Presence of insulin? Hexokinase or glucokinase?

A

1) Hexokinase - has a low affinity

2) Glucokinase

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65
Q

What is the net gain of glycolysis?

A

1) In: Glucose, 2Pi, 2ADP, 2NAD

2) Out: 2 Pyruvate, 2ATP, 2NADH, 2H, and 2H2O

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66
Q

What two steps in glycolysis require ATP?

A

1) Glucose to glucose 6 phosphate via Hexokinase/Glucokinase

2) Fructose 6 phosphate to Fructose 1,6 bisphosphate via phosphofructokinase (RATE LIMITING STEP)

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67
Q

What steps in glycolysis produces 4 total ATP from one glucose molecule?

A

1) 1,3 bisphosphoglycerate to 3 phosphoglycerate via phosphoglycerate kinase
2) Phsophoenolpyruvate to pyruvate via pyruvate kinase

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68
Q

What regulates phosphofructokinase-1 (PFK-1)

A

1) Positive: AMP and fructose 2,6 bisphosphate

2) Negative: ATP and citrate

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69
Q

What does fructose 2,6 bisphosphate regulate?

A

Increases Phosphofructokinase activity

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70
Q

How is the formation of fructose 2,6 bisphosphate regulated?

A

1) Formed from fructose 6 phosphate
2) In FED state phosphofructokinase 2 increases amount of fructose 2,6 bisphosphate leading to increased glycolysis
3) In Fasting state Fructose 2,6 bisphosphatase decreases the amount of fructose 2,6 bisphosphate leading to increased gluconeogenesis

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71
Q

What occurs in the Fed state in glycolysis/gluconeogenesis pathway?

A

1) Phosphofructokinase 2 is active
2) Increased amount of fructose 2,6 bisphosphatase
3) Leads to increased activity of PFK-1 –> glycolysis

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72
Q

What occurs in the Fasting state in glycolysis/gluconeogenesis pathway?

A

1) Fructose 2,6 bisphosphatase is active
2) Decreased amount of fructose 2,6 bisphosphate
3) Leads to decreased activity of PFK-1 –> more gluconeogenesis

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73
Q

What activates phosphofructokinase-2? Fructose 2,6 bisphosphatase?

A

1) Activated by decreased phosphorylation by protein kinase A (Insulin acts by tyrosine kinase which leads to activation of protein phosphatase)
2) Activated by phosphorylation by protein kinase A (glucagon increases cAMP –> increased activity of protein kinase A)

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74
Q

What activates the pyruvate dehydrogenase complex?

A

1) Increased NAD/NADH ratio
2) Increased Ca
3) Increased ADP

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75
Q

What is the net result from the activity of pyruvate dehydrogenase complex?

A

1) Pyruvate + NAD + CoA –> Acetyl CoA + CO2 + NADH

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76
Q

What inhibits lipoic acid?

A

Arsenic

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77
Q

What are findings of Arsenic poisoning?

A

1) Rice water stools
2) Vomiting
3) GARLIC BREATH

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78
Q

Pure Ketogenic amino acids?

A

Think: onLy pureLy

1) Lysine and Leucine

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79
Q

What are the different pathways that pyruvate can be metabolized?

A

1) Pyruvate –> Lactic acid via Lactic acid dehydrogenase (gain NAD)
2) Pyruvate –> Acetyl CoA via pyruvate dehydrogenase (gain NADH and CO2)
3) Pyruvate –> Oxaloacetate via Pyruvate carboxylase (requires CO2 and ATP)
4) Pyruvate –> Alanine via Alanine aminotransferase (uses B6)

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80
Q

What are the metabolites of the TCA cycle?

A

Think: Our City Is Kept Safe n Sound From Malice

1) Oxaloacetate
2) Citrate
3) Isocitrate
4) alpha Ketoglutarate (formation is RATE LIMITING step)
5) Succinyl CoA
6) Succinate
7) Fumarate
8) Malate

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81
Q

What are the metabolites of the TCA cycle?

A

Think: Our City Is Kept Safe n Sound From Malice

1) Oxaloacetate
2) Citrate
3) Isocitrate
4) alpha Ketoglutarate (formation is RATE LIMITING step)
5) Succinyl CoA
6) Succinate
7) Fumarate
8) Malate

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82
Q

What is produced from one round of the TCA cycle?

A

3 NADH, 1 FADH2, 2CO2, 1 GTP, and 10 ATP

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83
Q

What are the irreversible enzymes in gluconeogenesis?

A

Think: Pathway Produces Fresh Glucose

1) Pyruvate decarboxylase (Pyruvate –> Oxaleoacetate)
2) PEP carboxykinase (Oxaloacetate –> posphoenolpyruvate)
3) Fructose 1,6 bisphosphonate
4) Glucose 6 phosphatase

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84
Q

What is the purpose of the pentose phosphate pathway (HMP shunt)

A

1) Produce NADPH from glucose 6 phosphate

2) Provide ribose for nucleotide synthesis

85
Q

What is NADPH essential for?

A

1) Glutathione reduction inside rbcs; Reduce glutathione is used to reduce hydrogen peroxide and free oxygen radicals
2) Anabolic processes
3) P-450
4) Respiratory burst

86
Q

Where does the pentose phosphate pathway occur?

A

Cytoplasm

87
Q

What are the two distinct phases of the pentose phosphate pathway?

A

1) Oxidative (Glucose 6 Phosphate –> Ribulose-5-phosphate

2) Nonoxidative (Ribulose-5-phosphate –> ribose 5 phosphate)

88
Q

What enzyme and vitamin is required for the non-oxidative portion of the pentose phosphate pathway?

A

1) Transketolase
2) B1 (thiamine)
Think: ATP = Alpha ketoglutarate, Transketolase, Pyruvate dehydrogenase

89
Q

What is the inheritance of G6PD deficiency? What pathways are hindered? What is found histologically?

A

1) X linked
2) PPP (HMP shunt) pathway and Gluathione reduction
3) Heinz bodies (oxidized hemoglobin) and Bite cells (due to removal of heinz bodies)

90
Q

What must pt. with G6PD deficiency look out for in terms of exposures?

A

1) Fava beans
2) Sulfonamides
3) Primaquine
4) Antituberculosus drugs

91
Q

What enzyme is defective in essential fructosuria? Fructose intolerance?

A

1) Fructokinase (Asymptomatic; fructose in urine)

2) Aldolase B ( Hypoglycemia, cirrhosis, vomiting, and jaundice)

92
Q

Why is fructose the most quickly usable metabolite for glycolysis?

A

1) It bypasess the rate limiting step of glycolysis (PFK-1; fructose 1 phosphate –> Fructose 1,6 bisphosphate)

93
Q

What accumulates in galactokinase deficiency? Classic galactosemia?

A

1) Galactitol (Galactose is converted by Aldose reductase)

2) Galactose 1 phosphate

94
Q

What is worse galactokinase deficiency or classic galactosemia?

A

Think: Fructose is to Aldose B as Galactose is to UridylTransferase (FAB GUT)

1) Classic galactosemia (galactose 1 phosphate uridyltransferase)
More serious defects lead to phosphate depletion

95
Q

What are the steps involved with the urea cycle?

A

1) Formation of carbomyl phosphate (Carbomy phosphate synthase: RATE LIMITING STEP)
2) Carbomyl phosphate + Ornithine –> Citruline (Ornithine transcarbomylase)
3) Citruline –> Argininosuccinate (Argininosuccinate synthase)
4) Argininosuccinate –> Arginine (Argininosuccinase; production of fumarate)
5) Arginine –> Ornithine (Arginase; production of urea)

96
Q

Infant presents with lethargy, vomitting, jaundice, hepatomegaly, and bilateral cataracts (lack of red reflex) while taking breast milk

A

Galactosemia (defect in galactose 1 phosphate uridyltransferase)

97
Q

Chronic alcholoic comes in with diarrhea that has been going on for 3 months followed by pruruitic dermatitis in sun exposed areas. What will occur next if this pt. is not treated?

A

1) Dementia

2) this pt. has Pellagra (niacin deficiency)

98
Q

What pathway produces NADPH and what is the main metabolite for activation of this pathway?

A

1) Pentose phosphate pathway

2) Glucose 6 phosphate

99
Q

Vitamin that constitutent of visual pigments, essential for nomral differentation of epithelail cells into specialized tissue; Used to treat measels, Acute myelogenous leukemia; found in liver and leafy vegetables

A

Vitamin A (retinol)

100
Q

What is niacin derived from? What is required for synthesis?

A

1) Tryptophan

2) B6

101
Q

Causes for niacin deficiency?

A

1) Hartnup disease (decreased tryptophan absorption)
2) Malignant carcinoid syndrome (increased tryptophan metabolism)
3) INH use (Decrease in B6)

102
Q

What drug causes pyridoxine deficiency?

A

1) Isoniazid or Oral contraceptives

103
Q

Pantothenate; you should think

A

1) Co Enzyme A and Fatty acid synthase

2) Co factor for Acyl transferase

104
Q

What is the result of a B5 (pantothenate) deficiency?

A

1) Dermatitis
2) Enteritis
3) Adrenal insuffiency

105
Q

What is vitamin B6 involved with?

A

1) Synthesis of Heme, Niacin, cysteine, and histamine

2) Synthesis of neurotransmiters (Serotonin, epinephrine, norepinephrine and GABA)

106
Q

What is the result of a pyridoxine deficiency?

A

1) Sideroblastic anemia (Impaired heme metabolism)
2) Peripheral neuropathy
3) Pellagra
4) Convulsions
.

107
Q

Carboxylation. You should think this vitamine

A

Biotin (B7)

108
Q

When must folate be given to prevent neural tube defects?

A

1) Before pregnancy

109
Q

Methyl transferase. You should think this vitamin.

A

B12 (cobalamin)

110
Q

Causes of B12 deficiency

A

1) Malabsorption
2) Loss of intrinsic factor (pernicious anemia)
3) Absence of terminal ileum

111
Q

Where is folate taken up? Iron? B12?

A

1) jejunum
2) Duodenum
3) Ileum

112
Q

What is required for homocystiene to become methionine? To become cysteine?

A

1) B12 and methyl-THF

2) B6

113
Q

What is required to convert methylmalonyl-CoA into Succinyl CoA? What is succinyl CoA used for?

A

1) B12

2) TCA or formation of ALA (becomes Hb) when combined with glycine

114
Q

What is the formation of methionine used for?

A

1) Formation of SAM (Converts NE to epi)

115
Q

What is SAM formation dependent upon?

A

1) B12 and folate

116
Q

What is vitamin C necessary for?

A

1) Hydroxylation of proline and lysine in collagen

2) Convertion of Dopamine to NE

117
Q

Calcitriol

A

Active form of Vitamine D (1,25 dihydroxycholecalciferol)

118
Q

What is the result of low Calcitriol?

A

1) Low calcium and low phosphate

2) Hypocalcemic tetany

119
Q

What is the result of a vitamin E deficiency?

A

1) Increased fragility of RBCs
2) Posterior column and spinocrebellar tract demyelination (skeletal myopathy, spinocerebellar ataxia, pigmented retinopathy)

120
Q

Why are infants given Vitamin K intramuscularly?

A

1) Neonates have sterile intestines and are unable to synthesize vitamin K
2) Prevents neonatal hemorrhage
3) Vitamin K is not found in breast milk

121
Q

What is the result of Zinc deficiency?

A

1) Delayed wound healing

2) Decreased adult hair

122
Q

Antidote for methanol or ethylene glycol poisoning?

A

Fomepizole

123
Q

What causes the changes in metabolism when ethanol is present?

A

1) Increased NADH/NAD ratio
2) Body must attempt to regain enough NAD
3) Results in increased Lactate (acidosis), Malate (Increased NADPH -> fatty acid oxidation), decreased gluconeogenesis, ketone production from Acetyl CoA due to TCA inhibtion

124
Q

How is NAD regained in a cell?

A

1) Pyruvate –> Lactate
2) Oxaloacetate –> Malate
3) Both result in inhibition of gluconeogenesis

125
Q

Why is there fatty changes in Kwashiorkor? results in swollen belly.

A

1) Protein malnutrition results in decreased apolipoprotein

126
Q

MOA of Glucagon

A

1) Increases glucose formation (gluconeogenesis)
2) Increases cAMP –> Active phophokinase A
3) Active phophokinase A –> Phosphorylation of fructose 2,6 bisphosphatase
4) Leads to decreased Fructose 2,6 bisphosphate

127
Q

Infant who presents with the beginnings of neurologic defects and lactic acidosis. There is increased pyruvate and alanine. What enzyme is deficient?

A

1) Pyruvate dehydrogenase complex deficiency

128
Q

How does NADH enter the mitochondria to enter the electron transport chain?

A

1) Malate-aspartate shuttle

2) Glycerol 3 phosphate shuttle

129
Q

Where does the pentose phosphate pathway normally occur?

A

1) Lactating mammary glands
2) Liver
3) Adrenal cortex
Note: sites of fatty acid or steroid synthesis
4) RBCs

130
Q

What is essential for respiratory burst to occur?

A

1) NADPH oxidase must be present

2) NADPH causes an increase in ROI

131
Q

What is the result of NADPH oxidase deficiency?

A

1) Defective respiratory burst

2) Results in chronic granulomatous disease

132
Q

What are pt. with chronic granulomatous disease more at risk for?

A

1) infections with catalase positive bacteria because they neutralize their own H2O2 leaving WBCs with out ROIs for fighting infection

133
Q

What should you think with Heinz bodies and Bite cells? What would alleviate this disease?

A

1) Glucose 6 phosphate Dehydrogenase (X-linked)

2) Splenectomy

134
Q

What enzyme is involved in neutralizing hydrogen peroxide?

A

1) Glutathione peroxidase

2) Uses Reduced glutathione

135
Q

What enzyme reduces glutathione?

A

1) Glutathione reductase

136
Q

What does Gluathione reductase require?

A

1) NADPH

137
Q

Appearance of fructose in blood and urine; no other symptoms

A

1) Essential fructosuria

2) Defect in fructokinase

138
Q

Hypoglycemia, Jaundice, cirrhosis, and vomiting

A

1) Fructose intolerance
2) Defect in Aldolase B
Think: FAB GUT (Fructose = Aldolase B; Galactose = uridyltransferase)

139
Q

Why is hypoglycemia observed with Fructose intolerance?

A

1) Defective aldolase B results in increased amounts of fructose 1 phosphate that depletes phosphate storage
2) Decreased phosphate results in inhibition of glycogenolysis and gluconeogenesis

140
Q

What accumulates in galactokinase deficiency?

A

Galactiol (formed by aldose reductase)

141
Q

Galactose in blood and urine, infantile cataracts, failure to track objects or develop a social smile

A

Galactokinase deficiency

142
Q

What is the mode of inheritance for impairment of both fructose and galactose metabolism?

A

Autosomal recessive

143
Q

Infant comes in filing to thrive, jaundice, hepatomgaly, infantile cataracts, mental retardation

A

1) Classic galactosemia

2) Defect of galactose 1 phosphate uridyltransferase

144
Q

What converts glucose to sorbitol?

A

1) Aldose reductase

145
Q

Why is Sorbitol such a big problem in diabetes?

A

1) Excess glucose is taken up in CNS
2) Glucose converted to Sorbitol via aldose reductase
3) Sorbitol is converted to fructose via sorbitol dehydrogenase (however there is no sorbitol reductase in the CNS)
4) Remaining sorbitol causes osmotic damage (increase amount of liquid into cell)

146
Q

What is the function of aldose reductase?

A

1) Conversion of glucose to sorbitol

2) Conversion of galactose to galactitol

147
Q

What are the only places sorbitol dehydrogenase is not found?

A

1) Retina
2) Schwann cells
3) Kidneys

148
Q

Basic amino acids

A

Arginine, Lysine, and Histidine

149
Q

How is ammonia transferred from the muscle to the liver?

A

1) Use of Glutamate and Alanine
2) Glutamate and pyruvate form alpha ketoglutarate and alanine
3) Alanine carries nitrogen to liver

150
Q

Cori cycle

A

1) Conversion of pyruvate to lactate

151
Q

What converts alanine and alpha ketoglutarate to glutamate and pyruvate and vice-versa

A

Alanine aminotransferase (ALT)

152
Q

Pt. presents with tremor, slurring of speech, somnolence, vomiting, cerebral edema and blurring vision

A

Ammonia intoxication

153
Q

Pt. has orotic acid in urine, Decreased BUN, and Sx. of Hyperammonemia

A

OTC deficiency

154
Q

Pt. has dark connective tissue, brown pigmented slcera, urine turns black on prolonged exposure to air; may have arthalgias

A

Alkaptonuria (ochronosis)

155
Q

Causes of homocystinuria

A

1) Cystathionine synthase deficiency ( forms cystathionine, requires B12 and folate)
2) Decreased affinity of cystathionine synthase (Increase B6)
3) Homocysteine methyltransferase deficiency (forms methionine; requires B12)

156
Q

Autosomal recessive disorder characterized by defective neutral amino acid transporter on renal and intestinal cells; causes trypophan excretion in urine and decreased absorption; leads to niacin deficiency

A

Hartnup disease

157
Q

Defect of renal tubular transporter for cysteine, ornithine, lysine, and arginine

A

Cystinuria

158
Q

What are clincial findings of cystinuria

A

1) Hexagonal crystals

2) Renal staghorn calculi

159
Q

Pt. presents with debilitating arthalgias, dark blue pigmentation of cartilage in ears, brown slcera; urine turns black on exposure

A

Alkaptonuria

160
Q

Cause of alkaptonuria

A

Deficiency of homogentisic acid oxidase

161
Q

How does glucagon regulate glycogen?

A

Causes increased glycogenolysis due to lack of glucose

1) Glucagon via adenylyl cyclase results in increased cAMP
2) Increased cAMP leads to activation of Protein kinase A
3) Protein kinase A activates Glycogen phosphorylase kinase
4) Glycogen phosphorylase kinase activates glycogen phosphorylase
5) Glycogen phosphorylase starts glycogenolysis

162
Q

What is required for the enzymes that activate glycogenolysis?

A

1) Both glycogen phosphorylase kinase and glycogen phosphorylase require phosphorylation to be active

163
Q

How does insulin regulate glycogen?

A

1) Decreases glycogenolysis because insulin is released when there is an adequate supply of glucose
2) Acts via protein tyrosine kinase
3) Tyrosine kinase autophosphorylates and then phosphorylates protein phosphatases that remove phosphates from glycogen phosphorylase kinase and glycogen phosphorylase

164
Q

What hormone is found in the fasting state? Fed?

A

1) Glucagon

2) Insulin

165
Q

What are the glycogen storage diseases?

A

Think: Very Poor Carbohydrate Metabolism

1) Von Gierke’s disease (Type I)
2) Pompe’s disease (Type II)
3) Cori’s disease (Type III)
4) McArdle’s disease (Type IV)

166
Q

Pt. presents with severe fasting hypoglycemia, increased glycogen in the liver, increased lactate in blood, hepatomegally

A

1) Von Gierke’s disease

2) Defect in Glucose-6- phosphatase

167
Q

What glycogen storage disease causes cardiomegaly?

A

Think: Pompe’s trashes the PUMP (heart)

1) Pompe’s disease
2) Defect in Lysosomal alpha 1,4 glucosidase

168
Q

Milder form of Von Gierke’s disease with normal lactate levels

A

1) Cori’s disease (type III)

2) Defect in debranching enzyme

169
Q

Increased glycogen in the muscle, but cannot break it down, leading to painful cramps, myoglobinuria (dark urine)

A

1) McArdle’s disease

2) Defect in skeletal muscle glycogen phosphorylase

170
Q

Name the disease

1) Defect in glucose 6 phosphatase
2) Defect in lysosomal alpha 1,4 glucosidase
3) Defect in debranching enzyme
4) Defect in skeletal muscle glycogen phosphorylase

A

1) Von Gierkes disease (Increase lactate levels)
2) Pompe’s disease (Heart issues)
3) Cori’s disease (Normal lactate levels)
4) McArdle’s disease (Increased glycogen in muscle)

171
Q

Name the disease and accumulated substrate

1) Defect in alpha galactosidase A
2) Defect in glucocerebrosidase
3) Defect in sphingomyelinase
4) Defect in Hexosaminidase A
5) Defect in Galactocerebrosidase
6) Defect in arylsulfatase A
7) Defect in alpha-L-iduronidase
8) Defect in Iduronate sulfatase

A

1) Fabry’s disease; increased ceramide trihexoside
2) Gaucher’s disease; increased glucocerebroside
3) Niemann-Pick disease; increased sphingomyelin
4) Tay-Sachs disease; increased GM2 ganglioside
5) Krabbes disease; galactocerebroside
6) Metachromatic leukodystrophy; Cerebroside sulfate
7) Hurler’s syndrome; Heparan and dermatan sulfate
8) Hunter’s syndrome; Heparan and dermatan sulfate

172
Q

Infant presents with developmental delay, gargoylism, airway obstruction, corneal clouding, and hepatosplenomegaly

A

1) Hurler syndrome

2) Defect in alpha-L-iduronidase

173
Q

Infant that presents with aggressive behavior and a milder form of Hurler’s syndrome with no clouding of the corneas

A

Think: Hunter’s see clearly

Hunter’s syndrome

174
Q

Where does fatty acid metabolism take place?

A

1) Mitochondria

175
Q

1) What transport mechanism is involved with fatty acid synthesis? Degradation?

A

1) Citrate (think: SYtrate = Synthesis)

2) Carnitine (think Carnitine = Carnage)

176
Q

What are fatty acids and amino acids metabilized to when there is a stall in TCA cycle due to decreased metabolites?

A

1) Acetoacetate and beta-hydroxybutyrate

177
Q

How many calories are in 1 g of protein? carbohydrate? Fat? Ethanol?

A

1) 4 kcal
2) 4 kcal
3) 9 kcal
4) 7 kcal

178
Q

Describe the function of each apolipoprotein

1) Lipoprotein E
2) Lipoprotein A-I
3) Lipoprotein C-2
4) Lipoprotein B-48
5) Lipoprotein B-100

A

1) Mediates chylomicron remnant uptake
2) Activates LCAT (forms mature cholesterol)
3) Lipoprotein lipase cofactor
4) Mediates chylomicron secretion
5) Binds to LDL receptor

179
Q

Which apolipoproteins are in HDL? Chylomicron?

A

1) E, A-I, and C-II

2) E, C-II, and B-48

180
Q

Function of LDL? HDL?

A

1) Transports cholesterol from liver to tissues

2) Transports cholesterols from periphery to liver

181
Q

What is the only place apo-E is not found?

A

LDL

182
Q

Lipoprotein lipase deficiency or altered apolipoprotein C-II; pancreatitis, hepatosplenomegaly, pruritic xanthomas

A

Type I hyperchylomicronemia (autosomal recessive)

183
Q

Absent or decreased LDL receptors

A

Type II Famalial Hypercholesterolemia (autosomal dominant)

184
Q

Hepatic overproduction of VLDL; causes pancreatitis

A

Hypertriglyceridemia

185
Q

Decreased B-48 and B-100; results in decreased chylomicron and VLDL synthesis/secretion; results in malabsorption and fat vitamin deficiency

A

Abetalipoproteinemia

186
Q

What apolipoproteins are not found in IDL or LDL

A

1) A-I
2) C-II (cofactor of liporotein lipase)
3) B-48 (secretion of chylomicron)

187
Q

What does PEPCK require to make phosphoenol pyruvate?

A

1) GTP

2) Oxaloacetate

188
Q

Where is GTP produced in the TCA cycle? Where is FADH2 produced? where is NADH produced?

A

1) Succinyl CoA to Succinate
2) Succinate to fumurate
3) first: alpha ketoglutarate to succinyl co A; second: isocitarate to alpha ketogultarate; third: malate to OA

189
Q

Child with subperiostal hemorrhages, and gums that hurt

A

Ascorbic acid (vitamin C deficiency)

190
Q

What is the result of carnitine deficiency?

A

1) Defective beta oxidation

2) Decreased Acetoactetate

191
Q

What is required for fatty acid synthesis?

A

1) Citrate

2) Malonyl Co A

192
Q

Where does beta oxidation take place? Where does fatty acid synthesis take place?

A

1) Mitochondria

2) Cytoplasm

193
Q

What is the first step in beta oxidation?

A

1) Acyl-CoA –> Trans-enoyl-Co-A

Enzyme: Acyl-Co-A dehydrogenase

194
Q

What is the cofactor tetrahydrobioptrin (BH4) used to form?

A

1) Tyrosine
2) DOPA
3) Serotonin

195
Q

What is serotonin made from?

A

Tryptophan

196
Q

What amino acids are involved in the formation of the following:

1) Nitric oxide
2) Urea
3) Heme
4) Creatinine
5) GABA or Glutathione
6) Purines
7) Niacin
8) Serotonin

A

1) Arginine
2) Arginine + Aspartate
3) Glycine and Succinyl CoA
4) Glycine + Arginine + SAM
5) Glutamate
6) Glutamate, Aspartate, and Glycine
7) Tryptophan
8) Tryptophan

197
Q

What is Keq if Gibbs free energy is negative? positive?

A

1) Keq >1

2) Keq <1

198
Q

What occurs in thiamine deficiency that causes the symptoms of korsakoff syndrome?

A

1) Damage to the anterior and dorsomedial thalamic nuclei

2) Damage is irreversible

199
Q

How is ammonia neutralized during hyperammonemia?

A

1) Glutamate Glutamine cycel

200
Q

What is the glutamate glutamine cycle

A

1) Glutamate is converted to glutamine in astrocytes and then taken up by neurons (glutamine synthase)
2) In neurons glutamine combines with ammonia to make glutamate again (Glutaminase)
3) Glutmate goes back to the astrocyte and is converted again

201
Q

What occurs when the glutamate glutamine cycle is exhausted by hyperammonemia?

A

1) Results in increased amounts of glutamine in the astrocyte which causes swelling and mitochondrial dysfunction
2) Ammonia combines with alpha ketoglutarate to make glutamate; Results in exhaustion of alpha ketoglutarate

202
Q

What is the only location of the enzyme that converts glucose 6 phosphate to glucose? what is this enzyme?

A

1) Liver

2) Glucose 6 phosphatase

203
Q

What peripheral tissues are able to use ketones?

A

1) Any peripheral tissue with mitochondria

204
Q

What are the two main ketones formed in fasting states?

A

1) Acetoacetate

2) Beta hydroxybutyrate

205
Q

How are ketones converted into usable metabolites for glucose synthesis?

A

1) Ketones are brought in peripheral mitochondria and are converted to acetoacetyl CoA via Thiophorase
2) Acetoacetyl CoA is converted to acetyl acetate

206
Q

What increases progression of gluconeogenesis?

A

1) Acetyl acetate
2) Acetyl acetate is produced by conversion from pyruvate via pyruvate dehydrogenase
3) Abundant acetyl acetate pushes pyruvate to be converted to oxaleoacetate via pyruvate carboxylase (Biotin dependent)

207
Q

How are fatty acids implemented into beta oxidation?

A

1) Fatty acids are combined with CoA to make Acyl CoA via Fatty acid CoA synthase
2) Acyl CoA is transferted into the mitochondria via carnitine shuttle
3) Acyl CoA then undergoes beta oxidation

208
Q

What does Acyl CoA after going through beta oxidation become?

A

1) Acetyl CoA

209
Q

What converts acetyl CoA to ketone bodies?

A

1) HMG CoA synthase converts acetyl CoA to HMG CoA

2) HMG CoA is converted to ketone bodies via HMG CoA lyase

Biochemistry (5 decks)

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