open questions

Question 1

What is the cofactor of pyruvate carboxylase?

Answer 1

Biotin

Question 2

Which enzyme catalyses the link between acetyl-CoA and oxaloacetate?

Answer 2

Citrate synthase

Question 3

Which enzyme catalyses the formation of succinyl-CoA?

Answer 3

Methylmalonyl-CoA mutase (vitamin B12 dependent)

Question 4

What is the principal defect in familial hypercholesterolemia?

Answer 4

LDL receptor defect

Question 5

What is the function of ApoA1 apolipoprotein?

Answer 5

Activate LCAT to produce cholesterol ester from cholesterol

Question 6

When would you expect high free fatty acid level in plasma?

Answer 6

Under starvation/strenuous exercise/uncontrolled diabetes mellitus

Question 7

What is the allosteric inhibitor of carnitine acetyltransferase 1?

Answer 7

Malonyl-CoA

Question 8

Lipoproteins transporting lipids in the circulation from smallest to highest density

Answer 8

Chylomicron –> VLDL –> IDL –> LDL –> HDL

Question 9

Which enzyme catalyses the first committed step of fatty acid synthesis?

Answer 9

Acetyl-CoA carboxylase, cofactor: biotin

Cofactors: ABC

• ATP
• Biotin
• CO2

Question 10

What are the 2 major pathways for synthesis of eicosanoids?

Answer 10

Cyclooxygenase pathway + lipoxygenase pathway

Question 11

What enzyme liberates arachidonic acid for synthesis of eicosanoids?

Answer 11

Phospholipase A2

Question 12

What is the end-product steroid hormone in corpus luteum?

Answer 12

Progesterone

Question 13

Which cells cooperate in the production of estradiol from cholesterol?

Answer 13

Granulosa cells, SER

Question 14

Where does the E3 subunit of pyruvate DH complex also participate in?

Answer 14

• Alpha-ketoglutarate DH complex
• Branched chain amino acid complex
• Glycine-cleavage complex

Question 15

Why does hypoglycaemia develop in patients with fructose intolerance?

Answer 15

Accumulation of fructose-1-phosphate results in a phosphate trap. Decreased level of phosphate inhibit glycogen breakdown. This prevents production of ATP which inhibit gluconeogenesis  hypoglycaemia

Question 16

Hyperuricemia can develop in fructose intolerance and McArdle`s disease?

Answer 16

True

Question 17

How many FADH2, NADH + acetyl-CoA are formed in oxidation of 1 palmitoyl-CoA?

Answer 17

7 FADH2, 7 NADH, 8 acetyl-CoA

Question 18

Which protein is regulated in FA oxidation by malonyl-CoA?

Answer 18

Carnitine-palmitoyltransferase 1 = inhibited

Question 19

Which coenzyme is needed for the bile acid synthesis?

Answer 19

NADPH

Question 20

What enzyme catalyses the formation of mevalonic acid and what is its regulation?

Answer 20

HMG-CoA reductase

• Transcription: increased by SR
• Phosphorylation –> Degradation (?)
• Drugs: inhibited by statins

Question 21

Which protein is critical for intestinal cholesterol absorption?

Answer 21

NPC1L1

Question 22

Which organ is responsible for the elimination of lactate from the circulation?

Answer 22

Liver

Question 23

What is the reason for neurological disorders in pyruvate carboxylase deficiency?

Answer 23

Production of oxaloacetate will be inhibited therefore the activity of TCA cycle decrease and pyruvate is shunted towards lactate = lactic acidosis.
Due to inhibition of oxaloacetate production there will not be any aspartate formation as well  no myelination.

Question 24

Mc-Ardle`s disease is due to deficiency of which enzyme?

Answer 24

Muscle glycogen phosphorylase

Question 25

Do patients suffering from Mc-Ardle`s disease exhibit increase blood lactate?

Answer 25

No, because glycogenolysis is blocked due to deficiency in muscle glycogen phosphorylase. There is little production of glucose-6-phosphate and therefore glycolysis cannot proceed and there will be no lactate formation.

Question 26

Which substance accumulates in the liver in patients with fructose intolerance?

Answer 26

Fructose-1-phosphate

Question 27

Which enzyme is defect in fructose intolerance?

Answer 27

Aldolase B

Question 28

Name 2 lipoprotein which is cleaved by hepatic lipase?

Answer 28

HDL2 (?) | IDL to LDL

Question 29

What is the dominant chemical reaction in 1st phase of biotransformation?

Answer 29

Oxidation

Question 30

Which phase of biotransformation is mediated by transporters?

Answer 30

Phase 3

Question 31

What is the molecular basis of the primary systemic carnitine deficiency?

Answer 31

OCTN2 deficiency, the renal absorption of carnitine is defect

Question 32

What is the major organ that synthesises and supplies carnitine for other tissues?

Answer 32

Liver, kidney and brain

Question 33

Where is the location of lipoprotein lipase in adipose tissue?

Answer 33

In the luminal surface of endothelial cells of capillaries

Question 34

What is the first complex of respiratory chain?

Answer 34

NADH/NAD complex

Question 35

What kind of solubility change is caused by biotransformation?

Answer 35

Lipid soluble  water soluble (more polar)

Question 36

Which enzyme is defect in type 1 “classic galactosemia”?

Answer 36

Galactose-1-phosphate uridylyl transferase

Question 37

What are the product of the reaction catalysed by hormone sensitive lipase?

Answer 37

2 free fatty acids + monoacylglycerol

Question 38

What is the target of hormone sensitive lipase?

Answer 38

Triacylglycerides

Question 39

Which membrane proteins is necessary for the nascent HDL in the liver?

Answer 39

ABCA1 + apolipoprotein A1 + phospholipids + cholesterol

Question 40

List 3 things that would decrease the blood cholesterol level?

Answer 40

- Reduce saturated fat  decrease LDL - Eat omega-3 fatty acids - Eat soluble fibres  decrease absorption of cholesterol

Question 41

How does intracellular depletion of cholesterol influence LDL uptake?

Answer 41

Increase LDL uptake because of number of LDLR increase.

Question 42

What intracellular component contain the enzyme catalysing the activation of FA?

Answer 42

ER or outer mitochondrial membrane: acyl-CoA synthase

Question 43

In which organ are the secondary bile acids formed?

Answer 43

Large intestine

Question 44

Give the summary reaction of FA activation

Answer 44

R-COOH + CoA-SH + ATP  R-CO-SCoA + AMP + PP

Question 45

Which proteins are required for the transport of long-chain FA?

Answer 45

ATP, carnitine, CoA

Question 46

Which ketone bodies are synthesized in the body?

Answer 46

Acetoacetate, acetone, beta-hydroxybutyrate

Question 47

Which organs are able to utilize ketone bodies as fuel?

Answer 47

Muscle, kidney, heart, brain

Question 48

Where do the carbon atoms from cholesterol originate from?

Answer 48

Acetyl-CoA

Question 49

Name 2 receptors involved in uptake of cholesterol in hepatocytes

Answer 49

- LDL receptor | - Scavenger receptor B1 (SRB1)

Question 50

What is the substrate and product of methylmalonyl-CoA mutase?

Answer 50

- S: L-methylmalonyl-CoA - P: succinyl-CoA - Cofactor: vitamin B12

Question 51

Which enzymes are necessary for conversion of citrulline to ornithine?

Answer 51

Arginosuccinate synthase + lyase and arginase

Question 52

Which enzymes are necessary for conversion of free ammonia to citrulline?

Answer 52

Carbamoyl-phosphate synthase 1 + ornithine transcarbamoylase

Question 53

Which enzyme is defect in essential fructosuria?

Answer 53

Fructokinase

Question 54

Which dietary intakes provokes the symptoms of fructose intolerance?

Answer 54

Sorbitol + fructose + sucrose

Question 55

What enzyme catalyses the formation of cholesterol ester?

Answer 55

``` LCAT in plasma - transforms free cholesterol in blood - uses phosphatidylcholine (leichitin) ACAT in tissue cells - intracellular protein in ER - uses Acyl-coA ```

Question 56

What is the function of SRB1 (scavenger receptor B1)?

Answer 56

Binding of HDL

Question 57

What is the major organ that synthesises and supplies carnitine for other tissues?

Answer 57

Liver, kidney and brain

Question 58

What are the clinical signs of lipoprotein lipase deficiency?

Answer 58

- Hypertriglyceridemia - Hepatosplenomegaly - Pancreatitis

Question 59

What is the dominant chemical reaction in 1st phase of biotransformation?

Answer 59

Oxidation

Question 60

Which phase of biotransformation is mediated by transporters?

Answer 60

Phase 3

Question 61

What is the molecular basis of the primary systemic carnitine deficiency?

Answer 61

OCTN2 deficiency, the renal absorption of carnitine is defect

Question 62

What takes part in intestinal lipid digestion?

Answer 62

Pancreatic lipase and bile acids

Question 63

Which enzyme is only expressed in zona glomerulosa which enable aldosterone?

Answer 63

21 hydroxylase

Question 64

Which enzyme cleaves arachidonic acid from membrane phospholipids?

Answer 64

Phospholipase A2

Question 65

Which enzyme is inhibited by aspirin in platelets?

Answer 65

Cyclooxygenase 1 (COX1)

Question 66

Which enzyme and cofactor is needed to convert cholesterol to pregnonelone?

Answer 66

Cytochrome p450 side chain cleavage enzyme, cofactor; NADPH + O2

Question 67

What is the action of ouabain?

Answer 67

Inhibit Na+/K+ ATPase --> accumulation of intracellular Na+  reversed activity of Na/Ca2+ exchanger --> higher intracellular Ca2+ --> increase cardiac contractility

Question 68

Deficiency of acyl-CoA leads to?

Answer 68

NO ketone body synthesis

Question 69

What are the substrate-level-phosphorylation in glycolysis?

Answer 69

Phosphoglycerate kinase + pyruvate kinase

Question 70

What are the high energy compounds of glycolysis?

Answer 70

PEP + 1,3-BPG

Question 71

What is the consequence of IDOL deficiency?

Answer 71

More LDLR  more cholesterol influx  cholesterol plasma levels decrease

Question 72

Which enzyme contain FMN as prosthetic group?

Answer 72

Complex 1 of respiratory chain