Question

How was the asymmetry of membrane lipids discovered?

1) The lipid asymmetry was visualized in the electron microscope.
2) The lipid asymmetry was observed with a special stain in the light microscope.
3) Treatment of intact red blood cells with phospholipases.
4) Treatment of intact red blood cells with trypsin.
5) Treatment of liver cells with phospholipases.

Answer 1

The asymmetry of membrane lipids was discovered through various experiments and observations, including electron microscope visualization, cytochemistry, and treatment of cells with phospholipases and trypsin.

Step-by-step explanation:

The asymmetry of membrane lipids was discovered through various experiments and observations. One method was visualizing the lipid asymmetry in the electron microscope through the technique of freeze-fracture. This technique involved chipping ice crystals to reveal the split membranes, showcasing the different features on the interior and exterior surfaces.

Additionally, the asymmetry of membranes was demonstrated through cytochemistry. Special stains were used in the light microscope to show that only the external surfaces of plasma membranes were sugar coated.

Treatment of intact red blood cells with phospholipases and trypsin was another method to explore membrane asymmetry. Phospholipases and trypsin can break down specific components of phospholipids, allowing researchers to observe changes in membrane structure and asymmetry.