Question

How does the structure of the cellular membrane affect transportation in and out of a cell

Answer 1

STRUCTURE OF CELL MEMBRANE AND ITS ROLE IN TRANSPORT:

• The modern model of the cell membrane is the FLUID MOSAIC MODEL , as given by scientists Singer and Nicolson.

• The model says that the cell membrane contains lipid bi-layer containing surface proteins, integral (tunnel) proteins and polysaccharide chains. [Refer to diagram]

• The quasi-fluid nature of the cell membrane helps in easy transportation of materials across it (see below).

Now, transport of materials across the cell membrane (in/out of the cell) is made possible by three ways:

• Passive transport: The molecules get transferred across the cell membrane without the need for energy. For example : Gas molecules (namely carbon dioxide).

• Active transport: The molecules transferred across the cell membrane with the help of ATP (energy currency).

• Facilitated transport: Certain molecules are transported by a process of facilitated diffusion in which integral proteins help in transport of the molecules. For example: Glucose.

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