SIGNALING MOLECULES Meaning and
Definition
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Signaling molecules, also known as cell signaling molecules or extracellular signaling molecules, are substances that are utilized by living organisms to transmit signals between cells. These molecules play a crucial role in various physiological processes, allowing cells to communicate and coordinate their activities.
Signaling molecules can be classified into different groups depending on their structure and mode of action. One major group consists of small molecules such as hormones, neurotransmitters, and growth factors. These molecules are produced by one cell and act on neighboring or distant cells to elicit a specific response. They can bind to specific receptors on the surface or within the target cells, initiating a signaling cascade that ultimately leads to a cellular response.
Another group of signaling molecules includes larger, protein-based molecules such as cytokines and chemokines. These molecules are typically involved in immune system functions, regulating cell growth, inflammation, and immune responses. They can also act locally or systemically, binding to specific receptors and activating cellular processes.
Furthermore, signaling molecules may function through various mechanisms, including paracrine, endocrine, autocrine, and juxtacrine signaling. In paracrine signaling, the signaling molecule is released by a cell and acts on nearby cells. Endocrine signaling involves the release of signaling molecules, often hormones, into the bloodstream to reach distant target cells. Autocrine signaling occurs when a cell releases a signaling molecule that acts on itself, while juxtacrine signaling involves direct contact between adjacent cells, transmitting signals through membrane-bound molecules.
Overall, signaling molecules are essential for maintaining homeostasis, coordinating development, and regulating cellular responses in living organisms.
Etymology of SIGNALING MOLECULES
The term "signaling molecules" is composed of two words: "signaling" and "molecules".
1. Signaling: The word "signaling" is derived from the verb "to signal", which comes from the Middle English word "signale" and Latin word "signare", meaning "to mark" or "to make known". In the context of biology, signaling refers to the process by which cells communicate with each other to convey information.
2. Molecules: The word "molecule" originates from the Latin word "molecula", meaning "a small mass". It is a diminutive form of "moles", meaning "mass" or "barrier". In the field of chemistry, molecules are the smallest units of a chemical compound that retain the chemical properties of that compound.
