Question 1

Which of the following best describes the structure of a glycerophospholipid?

Accepted Answer

A molecule containing a glycerol backbone, two fatty acids, and a phosphate group esterified to an alcohol

Question 2

Cardiolipin is a unique phospholipid found almost exclusively in which cellular structure?

Accepted Answer

Mitochondrial membrane

Question 3

Which of the following is the immediate precursor for the synthesis of all other glycerophospholipids?

Accepted Answer

Phosphatidic acid ($$\mathrm{PA})$$

Question 4

A patient with a deficiency in sphingomyelinase is most likely to accumulate which compound, and what disease does this cause?

Accepted Answer

Sphingomyelin; Niemann-Pick disease

Question 5

Which of the following best explains why low-dose aspirin is effective in reducing the risk of heart attacks?

Accepted Answer

It irreversibly inhibits COX-1 in platelets, reducing thromboxane A2 ($$\mathrm{$$TXA_2$$}) $$synthesis and thus platelet aggregation

Question 6

Which of the following reactions is catalyzed by phospholipase C in the phosphoinositide pathway?

Accepted Answer

Hydrolysis of phosphatidylinositol 4,5-bisphosphate ($$\mathrm{$$PIP_2$$}) to $$produce diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP$$_3)$$

Question 7

A newborn presents with severe neurodegeneration, hepatosplenomegaly, and accumulation of sphingomyelin in the CNS. Which enzyme is most likely deficient?

Accepted Answer

Sphingomyelinase

Question 8

Which of the following best describes the role of phosphatidylinositol (PI) in cell signaling?

Accepted Answer

It acts as a reservoir for arachidonic acid and is involved in the generation of second messengers upon cleavage

Question 9

Which of the following statements about glycosphingolipids is TRUE?

Accepted Answer

They are degraded in the lysosome by acid hydrolases

Question 10

Which of the following is a distinguishing feature of gangliosides compared to other glycosphingolipids?

Accepted Answer

Presence of one or more N-acetylneuraminic acid (NANA) residues

Question 11

A patient with asthma is prescribed a leukotriene receptor antagonist. Which pathway is being targeted by this medication?

Accepted Answer

Lipoxygenase (LOX) pathway

Question 12

Which of the following best explains why platelets are unable to recover cyclooxygenase (COX) activity after aspirin treatment, while endothelial cells can?

Accepted Answer

Platelets lack nuclei and cannot synthesize new COX enzyme, while endothelial cells can

Question 13

Which of the following is the correct sequence for the synthesis of phosphatidylcholine (PC) from choline?

Accepted Answer

Choline phosphorylation → formation of CDP-choline → transfer to diacylglycerol (DAG)

Question 14

Which of the following best describes the function of lung surfactant, and which phospholipid is its major component?

Accepted Answer

Reduces surface tension in alveoli; major component is dipalmitoylphosphatidylcholine (DPPC)

Question 15

Which of the following is a correct statement regarding the synthesis of eicosanoids?

Accepted Answer

Arachidonic acid is released from membrane phospholipids by phospholipase A$$_2$$

Question 16

A defect in the enzyme responsible for adding sulfate to galactocerebroside would most directly affect the synthesis of which compound?

Accepted Answer

Sulfatide

Question 17

Which of the following best describes the role of glycosyl phosphatidylinositol (GPI) anchors in the plasma membrane?

Accepted Answer

They covalently attach proteins to the outer leaflet of the plasma membrane, allowing lateral mobility

Question 18

Which of the following is a common feature of all sphingolipidoses?

Accepted Answer

They involve the accumulation of a specific sphingolipid due to a deficiency of a lysosomal hydrolase

Question 19

Which of the following best explains the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on prostaglandin synthesis?

Accepted Answer

NSAIDs inhibit both COX-1 and COX-2, blocking the conversion of arachidonic acid to prostaglandin H$$_2$$ ($$\mathrm{$$PGH_2$$})$$

Phospholipid, Glycosphingolipid, and Eicosanoid Metabolism: Study Notes

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