Q10.54P - Chemistry: Molecular Nature Of Matter And Change

Question

Explain in general why the shape of a biomolecule is important to its function.

Step-by-Step Solution

Answer

The shape of a biomolecule is important to its function as it helps to understand the specific function of the specific biomolecule through the lock and key theory. 

Step 1: Definition of Biomolecule

Biomolecules or biological molecules are molecules made up of cells present in living organisms which has a wide variety of size and structures that perform a range of functions or biological processes.

The four major types of biomolecules are carbohydrates, lipids, nucleic acids and proteins.

Step 2: The Lock and Key Theory

• Biomolecules are made up of biological cells consisting of molecular shapes interacting with aqueous fluids that are surrounded by membranes.
• When complex functions in the organism start, the ‘molecular key’ (generally smaller molecule, moving in body fluid) fits into a respective shaped ‘molecular lock’ (larger molecule also called receptor site, surrounded in a cell membrane).
• The receptor has a specific shaped site called the receptor site. Molecules that correctly fit into this shape (molecular key) are landed, and then they are grabbed by the receptor site through intermolecular attractions by starting the biological response.
• When the molecule with a different shape enters the receptor site, then this molecule will not fit in and thus, the particular function is not done. 

Step 3: Molecular Shapes Operation in Olfaction (Sense of Smell)

• Molecules in the odorous substances that comes from gas, volatile liquid or solid travel through the air. 
• To reach the receptor, these molecules should be soluble enough in the thin film of aqueous solution that is present in the nasal passage. 
• The main condition is, that the odorous molecule should have a specific shape, which should fit the olfactory receptor site, which connects the nerve endings in the nasal passage. 
• When this happens, the nerve impulses travel from these endings to the brain, which further infers the impulses as a particular odour.
• The below diagram shows how odorous molecules fit into the olfactory receptor site.

Thus, the shape of a biomolecule is very important for its function.