GI Lipid Metab & Membrane Lipids MCQ's
A membrane lipid is a compound, which belongs to a group of which form the double-layered surfaces of all cells. Lipid metabolism is the synthesis and degradation of lipids in cells where fat are broken down for energy. Take up the gi lipid metab & membrane lipids MCQ's below to see how well you understood the course.
- 1.Treatment of hypercholesterolemia requires knowledge of the control of HMG-CoA reductase activity and LDL receptor (LDLR) levels. Which of the following statements is correct concerning HMG-CoA reductase and the LDLR?
- A.
Their synthesis in the liver is increased after a meal containing cholesterol and cholesterol esters
- B.
They both contain CoA
- C.
When the LDLR is up-regulated, HMG-CoA reductase is switched on.
- D.
HMG-CoA reductase is activated when the LDLR is down-regulated and the cell requires cholesterol
- E.
Both HMG-CoA reductase and the LDLR are synthesized in response to high levels of intracellular cholesterol
- 2.Inhibiting the rate limiting enzyme of cholesterol biosynthesis would be beneficiary in lowering blood cholesterol levels by one of the following mechanisms:
- A.
Increasing the conversion of cholesterol to bile acids
- B.
Inhibiting the formation of HMG-CoA
- C.
Preventing the reabsorption of bile acids from the intestine
- D.
Inhibiting the formation of mevalonate
- E.
Inhibiting the absorption of cholesterol from the diet
- 3.Which of the following phospholipids is released by phagocytic cells and leads to superoxide radical production in alveoli macrophages?
- A.
Plasmalogens
- B.
Phosphatidylinositol
- C.
Cardiolipin
- D.
Platelet activating factor
- E.
Phosphatidylcholine
- 4.A mother takes her one-year-old daughter to the pediatric clinic because she observes that the child keeps walking into objects and does not respond when she talks to her. On examination the pediatrician notes that she has problems with her hearing and cannot see. Other observations included muscle weakness and slow mental and motor development. This patient most likely has which one of the following diseases:
- A.
Tay-Sachs
- B.
Fabry
- C.
Krabbes
- D.
Neimann-Pick
- E.
Faber
- 5.Patients with hypothyroidism also present with secondary hypercholesterolemia. One of the reasons for this is:
- A.
HMG-CoA red uctase is activated due to low levels of thyroid hormones
- B.
Low density lipoprotein receptors are upregulated in these patients
- C.
Large amounts of cholic acid are reabsorbed from the intestine which feeds back to 7-a-hydroxylase resulting in inactivation of the enzyme
- D.
High levels of thyroid hormones increase the synthesis of cholesterol
- E.
Thyroid hormones are necessary for the activation of 7a-hydroxylase
- 6.A deficiency in the activity of medium chain acyl-CoA dehydrogenase, an enzyme in the pathway for beta-oxidation of fatty acids, is corrected by large doses of its vitamin component in some patients. Which of the following compounds is the vitamin component of this enzyme?
- A.
Carnitine
- B.
Vitamin E
- C.
Riboflavin
- D.
Niacin
- E.
Thiamine
- 7.A patient presents to your clinic complaining of weakness and pain in the muscle and a general lack of energy. A blood test shows that he has high levels of creatine kinase and myoglobin. Urine analysis reveals very low levels of acetoacetate. This patient most likely has which of the following?
- A.
Complete absence of medium chain acyl-CoA dehydrogenase
- B.
Deficiency in one of the enzymes in the ketone body synthetic pathway
- C.
Carnitine deficiency
- D.
A low fat, high carbohydrate diet
- E.
Decreased production of insulin
- 8.During starvation ketone bodies are synthesized in one of the following organs:
- A.
Skeletal muscle
- B.
Spleen
- C.
Liver
- D.
Heart
- E.
Brain
- 9.A 29-year-old male decides to go on the Atkins diet. After approximately a month on the diet he complains of having what he describes as bad breath. What would be the biochemical findings in this patient?
- A.
Increased synthesis of fatty acids in adipose tissue due to excess free fatty acids released from adipose tissue
- B.
Decreased gluconeogenesis due to lack of activation of pyruvate carboxylase
- C.
Decreased levels of free fatty acids and undetectable ketone bodies in the plasma due to inactivation of LPL
- D.
Increased synthesis and recycling of fatty acids by the liver leading to increased adipose tissue storage of fats
- E.
Increased beta-oxidation due to increased activity of hormone sensitive lipase with subsequent increase in ketone bodies in plasma
- 10.What is the importance of citrate in fatty acid metabolism?
- A.
Activation of fatty acid synthetase
- B.
To act as a precursor for addition of one carbon units
- C.
Activation of acetyl-CoA carboxylase
- D.
To add the activated carbon dioxide in the formation of malonyl-CoA
- E.
Activation of carnitine acyl transferase
- 11.The reducing equivalents necessary for fatty acid synthesis are produced during the conversion of:
- A.
Glyceraldehyde-1, 3-bisphosphate to 3-phosphoglycerate
- B.
Glucose-6-phosphate to ribulose-5-phosphate
- C.
Glucose-6-phosphate to fructose-6-phosphate
- D.
Citrate to malate
- E.
Pyruvate to lactate
- 12.When excess acetyl-CoA, produced by the liver, cannot be used by the TCA cycle, it accumulates in the body as:
- A.
Glucose
- B.
Triglycerides
- C.
P-hydroxybutarate
- D.
Acetyl-CoA
- E.
Glycogen
- 13.Which of the following disorders of glucocerebrosidase metabolism can be treated by bone marrow transplant?
- A.
Fabrys
- B.
Tay-Sachs
- C.
Nieman-Pick
- D.
Gauchers
- E.
Krabbes
- 14.Which of the following organelles, which is defective in Gauchers disease, contains enzymes that degrade complex carbohydrates, proteins and complex lipids?
- A.
Lysosome
- B.
Peroxisome
- C.
Mitochondrion
- D.
Endoplasmic reticulum
- E.
Plasma membrane
- 15.Some of the apoproteins have very important functions in lipoprotein metabolism. Which of the following apoproteins is an important activator of lecithin cholesterol acyl transferase (LCAT)?
- A.
Apo All
- B.
Apo Al
- C.
Apo CII
- D.
Apo AIV
- E.
Apo E
- 16.Prostaglandins are synthesized from which of the following essential fatty acids?
- A.
Linolenic acid
- B.
Linoleic acid
- C.
Arachidonic acid
- D.
Ecosapentanoic acid
- E.
Palmitic acid
- 17.In patients with systemic lupus erythematosus, autoantibodies are produced to a membrane lipid in platelets, resulting in blood clotting disorders. This membrane lipid is:
- A.
Phosphatidylserine
- B.
Cardiolipin
- C.
Phosphatidyl inositol
- D.
Dipalmitoylphosphatidylcholine
- E.
Platelet activating factor
- 18.A 5-year old female is presented with hepatosplenomegaly, abnormal bleeding disorders, defects in long bone development and neurological dysfunction. Laboratory analysis of a liver biopsy reveals that the patient has only 30 % activity of the enzyme glucoceribrosidase. This patient most likely is suffering from one of the following diseases:
- A.
Fabrys
- B.
Sandhoff-Jatzkewitz
- C.
Krabbes
- D.
Gauchers
- E.
Neimann-Pick
- 19.A 22-year-old woman with poorly controlled gestational diabetes delivers a large -forgestational-age infant at 24 weeks. Within six hours of birth the baby develops respiratory difficulties associated with rapid respiration and cyanosis. Which of the following substances is most likely deficient in this newborn?
- A.
Cardiolipin
- B.
Ceramide
- C.
Sphingomyelin
- D.
Dipalmitoyl phosphatidylcholine
- E.
Ganglioside
- 20.The site of action of the nonsteroidal anti-inflammatory drugs is:
- A.
Thromboxane synthase
- B.
Prostaglandin E dehydrogenase
- C.
Lipoxygenase
- D.
Cyclooxygenase
- E.
Prostacyclin synthase
- 21.Which of the following phospholipids induces hypersensitivity, triggers thrombotic events and causes alveolar macrophages to generate superoxide radicals?
- A.
Cardiolipin
- B.
Phosphatidylinositol
- C.
Plasmalogens
- D.
Dipalmitoylphophatidylcholine
- E.
Platelet activating factor
- 22.Cytidine nucleotides are involved in phospholipid synthesis because:
- A.
They are involved in the activation of choline, ethanolamine and diacylglycerol (DAG)
- B.
They provide the energy to convert choline to ethanolamine
- C.
They are involved in the phosphorylation of choline and ethanolamine
- D.
They are recognition molecules for phospholipid transferases
- E.
They are important in signal transduction
- 23.Lipoprotein lipase is a very important enzyme in lipid metabolism. Found on many tissues in the body its main function is to facilitate the fatty acid uptake in these tissues. In a patient with severely decreased insulin output after a meal, what would you expect to be the metabolic outcome?
- A.
The patient can go into cardiac arrest because of lack of fatty acids for ATP production.
- B.
A plasma sample taken 45 minutes after a meal would reveal high levels of triglycerides due to lack of function of adipose tissue lipoprotein lipase
- C.
Coma could result because of lack of fatty acids as fuel for the brain
- D.
The patient would present with low levels of plasma ketone bodies due to lack of uptake of fatty acids in liver
- E.
A plasma sample would reveal both low levels of triglycerides and glucose
- 24.A patient reports to you that he has had aches and pains in his muscles for the past seven days. A blood test shows increased levels of creatine kinase MM, fatty acids and also myoglobin. A second blood sample, this time taken after an overnight fast, revealed low levels of blood glucose and elevated very low density lipoprotein (VLDL). This patient most likely has which of the following conditions?
- A.
Essential amino acid deficiency
- B.
Type 1 glycogen storage disease
- C.
Acute alcohol toxicity
- D.
Carnitine acyltranferase deficiency
- E.
Elevated insulin levels, which cause the hypoglycemia and increase fatty acid mobilization from adipose tissue
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