Metabolism of Acylglycerols and Sphingolipids MCQs

Explanation: Thermogenin , also known as Uncoupling Protein 1 (UCP1) , is located in the inner mitochondrial membrane of brown adipose tissue (BAT) . (Option A,C and D ruled out) Its primary function is non-shivering thermogenesis . UCP1 acts as a proton channel, allowing protons to leak back into the mitochondrial matrix without passing through ATP synthase. This uncouples oxidative phosphorylation from ATP synthesis, dissipating the proton gradient energy as heat to maintain body temperature, especially in newborns and hibernating mammals. Key Takeaways: Thermogenin (UCP1) is an uncoupling protein found in the mitochondria of brown adipose tissue. It generates heat by uncoupling electron transport from ATP production.

Ganglioside Sphingosine + Fatty acid + Oligosaccharide that contain one, two, three or four molecules of sialic acid. Gangliosides are complex glycosphingolipids derived from glucosylceramide that contain one or more molecules of a sialic acid. Neuraminic acid is the principal sialic acid found in human tissues. Gangliosides are present in nervous tissues in high concentration. They function in cell-cell recognition and communication as a receptor for hormone. Reference: Harper's 32nd edition, page 218

Glycosphingolipids are non phosphorylated lipid. GLYCOLIPIDS (GLYCOSPHINGOLIPIDS) ARE IMPORTANT IN NERVE TISSUES & IN THE CELL MEMBRANE. All other phospholipids are derivatives of phosphatidic acid, in which the phosphate is esterified with one OH group of glycerol and the other two OH groups are esterified to two long chain fatty acids (glycerophospholipids). Phosphatidic acid is important as an intermediate in the synthesis of triacylglycerols as well as phosphoglycerols but is not found in any great quantity in tissues. Reference: Harper's 32nd edition, page 215,218

Phosphatidic acid is a precursor of phosphatidylglycerol, which in turn gives rise to cardiolipin. This phospholipid is found only in mitochondria and is essential for the mitochondrial function. Decreased cardiolipin levels or alterations in its structure or metabolism cause mitochondrial dysfunction in aging and in pathological conditions including heart failure, hypothyroidism, and Barth syndrome (cardioskeletal myopathy). Reference: Harper's 32nd edition, page 217

All glycolipids are formed from the alcohol Sphingosine. They are widely distributed in the body most commonly found in neurons They are found in the OUTER leaflet of the plasma membrane; Phosphatidyl serine is generally always present on th inner leaflet of plasma membrane (except during apoptosis) The glycosphingolipids differ from sphingomyelin in that they do not contain phosphate Reference: Harper's illustrated biochemistry 32nd edition, page:576-77

Sphingomyelin, a sphingosine-based phospholipid, is a major structural lipid in the membranes of nerve tissue and. Is the only Sphingophospholipid. Cardiolipin(phosphatidylglycerol), Lecithin(Phosphatidylcholine) are PHOSPHOLIPIDS and DHA(docosahexaenoic acid/ceronic acid) is an unsaturated fatty acid. Reference: Harper's illustrated biochemistry 32nd edition page 489 and LIPPINCOTT illustrated reviews 6 th edition biochemistry page 202.

Ans. is `b' i.e.,Insulin [Ref Harper 29"Ve p. 246, 247]

Explanation: Rotavirus binds to GM1 and GM3 gangliosides on intestinal epithelial cells for attachment and entry into the cells. Causes gastroenteritis , leading to vomiting, diarrhoea, and fever , primarily in young children.