Practice question

Lipid droplets defy classic bilayer vesicle definition possessing neutral core surrounded by monolayer explaining unique buoyancy density microscopy appearance. Emergence begins when DGAT1 DGAT2 synthesize triacylglycerol DAG acyl CoA ACAT1 ACAT2 forms cholesteryl ester accumulating between ER leaflets forming oil lens twenty to sixty nanometers growing via Ostwald ripening coalescence regulated Seipin LDAF1 perilipin recruitment. Lens buds toward cytosol coated phospholipid monolayer enriched PC PE lyso PC preventing coalescence decorated perilipin family PLIN1 five CIDE proteins Seipin Rab18 regulating lipolysis contacts mitochondria peroxisomes for beta oxidation fatty acid exchange energy provision. Function storing energy five kilocalories per gram sequestering toxic free fatty acids cholesterol preventing lipotoxic ER stress unfolded protein response providing precursors membrane synthesis eicosanoids prostaglandins. Mobilization ATGL PNPLA2 HSL LIPA lipases and lipophagy via Rab7 LC3 autophagy. They contain hundreds associated proteins contrary protein free notion and do not produce ATP via oxidative phosphorylation which occurs mitochondria matrix. Understanding monolayer architecture explains why droplets float density gradients expand obesity metabolic syndrome nonalcoholic fatty liver disease pathology and diabetes insulin resistance cellular metabolism context for biomedical exams.