Question

Explain why it is important for cells to have a variety of ways to transport materials acroos the cell membrane. Be specific.

Answer 1

A variation in the transportation process is required because a cell contains many different types of molecules and the nature of plasma membrane is not same like the molecules being transported.

The plasma membrane is hydrophobic in nature because the core of the membrane is made up of hydrophobic fatty acid molecules. So hydrophobic molecules like hydrophobic amino acids, fatty acid can easily travel the membrane. It is because these hydrophobic molecules can easily interact with the hydrophobic fatty acid molecules. Diffusion and Osmosis are the main transport processes for these type of molecules.

But on the other hand there are big size molecules like cholesterol and charged ions like sodium ions and potassium ions and hydrophilic molecules like glucose which are not of similar type like that of the hydrophobic core of the membrane. These are hydrophilic molecules are charged molecules and cannot form association with hydrophobic fatty acids. This is the reason some other type of transport must be present inside the cell for the transportation of these molecules. This type of molecules are transported mainly by facilitated diffusion and active transport.

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