Question

The following experiment was conducted to test the fluid mosaic theory. The lipid bilayer of a cell was saturated with fluorescence, so that it appeared green when viewed under a microscope. The cell membrane was then bleached of colour in a single spot, which appeared white against the green of the rest of the cell membrane when viewed under a microscope. If the cell were left for a time, what would you expect to see when the cell is again viewed under a microscope?

Now choose from one of the following options

a The cell membrane will be white with a green spot.

b The cell membrane will be green with a white spot.

c The entire cell membrane will be white.

d The entire cell membrane will be green.

Answer 1

Option 'd' is the correct answer.

The entire cell membrane will be green because of the movement of bleached phospholipid molecules within the bilayer causing the white spot to diminish in the membrane. Cell membrane has a dynamic, fluid structure, meaning phospholipids are free to move within the bilayer, either laterally or in transverse manner between both leaflets of the bilayer. When the cells were left for a time, the bleached phospholipids got diffused through the entire membrane leading to a diminished white color so that the entire membrane appears green.