Question

Describe the structure of a wax. Where do waxes occur naturally in living creatures, and what function do they serve?

Short answer

Waxes are composed of long-chain fatty acids esterified to long-chain alcohols, with a general formula of \( RCOOR' \), where R and R' are long hydrocarbon chains. They naturally occur in both plants and animals, providing waterproofing, protection from pathogens and ultraviolet radiation, construction and structural support, maintenance of body temperature, and lubrication. Examples include plant cuticles and beeswax in honeycombs.

Step-by-step solution

Molecular structure of waxes

The structure of a wax is composed of long-chain fatty acids esterified to long-chain alcohols. A wax molecule can be represented by the following general formula: \( RCOOR' \) Here, R and R' represent long hydrocarbon chains, typically containing between 14 and 36 carbons.

Occurrence of waxes in living creatures

Waxes are naturally occurring substances in many living organisms, including plants and animals. Some examples include: 1. Plant waxes: Waxes are found on the outermost layer of plants, such as leaves, stems, and fruits. They form the cuticle of a plant, which offers protection against water loss, pathogens, and ultraviolet radiation from the sun. 2. Animal waxes: In animals, waxes play a crucial role in specific functions. For instance, beeswax, secreted by bees, is used to construct honeycombs. In mammals, earwax (cerumen) is produced in the auditory canal, providing a protective barrier against bacteria, fungus, and insects.

Functions of waxes in living creatures

Waxes serve several essential functions in living organisms, including the following: 1. Waterproofing and water repellency: Waxes help to reduce the water loss through the epicuticular layers in both plant and animal cells. In plants, they provide a protective covering on leaves, stems, and fruits, preventing excess evaporation. In animals, waxes help maintain the waterproof nature of fur or feathers. 2. Protection from pathogens and ultraviolet radiation: Waxes form a barrier on the surface of organisms, protecting them from harmful pathogens and UV radiation. This protective shield not only safeguards plants but also keeps insect and animal exoskeletons safe from external damage. 3. Construction and structural support: Waxes aid in the construction of functional structures, like the honeycombs made of beeswax in a beehive. These waxes help to provide a strong, yet flexible, support system for honey storage and brood rearing. 4. Maintenance of body temperature: Waxes play a role in the thermoregulation of some animals, such as the whale, which has a layer of waxy blubber right beneath the skin. This specialized insulating layer of fat helps whales maintain their body temperature in the cold aquatic environment. 5. Lubrication and protection: In mammals, cerumen or earwax prevents the auditory canal from drying out while providing a self-cleaning mechanism and protecting against bacterial and fungal infections.