This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of lipid, Subject name: Biochemistry
[{'content': 'To be defined as a ganglioside,a lipid substance isolated from nervous tissue must contain \nSelect and explain. \nA. NANA,hexose,fatty acid,glycerol, B. NANA,hexose,fatty acid,phosphorycholine, C. NANA,sphingosine,ethanolamine, D. NANA,hexose,sphingosine,long chain fatty acid,', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Gangliosides are the complex glycosphingolipids derived from glucosylceramide that contain in addition one or more molecules of sialic acid. Neuraminic acid is the principal sialic acid found in human tissues. Gangliosides are present in nervous tissue in high concentration.They help in cell-cell recognition and communication and as receptors for hormones and bacterial toxins. Reference: Harpers illustrated biochemistry 30 th edition', 'role': 'assistant'}]