Evidence of the Fluid Mosaic Model

What model of membrane structure did Singer and Nicolson propose in 1972?

The fluid mosaic model.

What does the 'fluid' in the fluid mosaic model refer to?

The lateral movement of molecules in the membrane.

What does the 'mosaic' in the fluid mosaic model refer to?

The random pattern of proteins in the membrane.

What technique provided evidence for the mosaic structure of the membrane?

Freeze fracture electron microscopy.

What is observed when the cell membrane is fractured using freeze fracture electron microscopy?

A speckled effect caused by the exposed proteins.

What was one experiment used as evidence for fluidity in the membrane?

Hybridization of cells, where two cells are fused together.

What happens to the red and green dyed proteins an hour after fusion in the hybridization experiment?

They disperse evenly across the membrane.

What does the dispersion of red and green dyed proteins indicate?

That the proteins move laterally within the membrane.

What is another method used to investigate membrane fluidity aside from hybridization?

Dyeing either phospholipid or protein molecules or attaching fluorescent markers and bleaching an area.

What happens to the bleached areas in the membrane over time?

The bleached areas 'disappear' as the bleached and marked molecules mix.