"Molecule" - what is it, definition of the term
A molecule is a discrete chemical entity composed of two or more atoms held together by covalent bonds, forming a stable arrangement that possesses distinct physical and chemical properties independent of its constituent elements.
Detailed information
A molecule is the smallest unit of a chemical substance that retains its composition and properties. It consists of two or more atoms bonded together, forming a discrete entity that can participate in chemical reactions.
In arthropods such as ticks, true bugs, lice, and fleas, molecular structures determine physiological functions. Key categories include:
- Structural polymers – chitin chains provide exoskeletal rigidity; protein fibers such as keratin contribute to mouthpart durability.
- Energy carriers – adenosine triphosphate molecules store and release energy for locomotion, feeding, and reproduction.
- Signal mediators – neuropeptides and hormone-like compounds regulate development, molting, and host‑seeking behavior.
- Detoxification agents – glutathione and related thiol-containing molecules protect cells from oxidative stress caused by blood meals.
Each organism synthesizes a specific complement of these entities. For example, ticks synthesize anticoagulant proteins that bind to host blood factors, while lice produce cuticular lipids that reduce desiccation. Fleas generate pheromone molecules that facilitate aggregation and mating.
Understanding the composition and interaction of these chemical units enables the development of targeted control measures, such as inhibitors that disrupt chitin synthesis or compounds that block neuropeptide receptors.