Search results
Results from the WOW.Com Content Network
The study of molecules by molecular physics and theoretical chemistry is largely based on quantum mechanics and is essential for the understanding of the chemical bond. The simplest of molecules is the hydrogen molecule-ion, H 2 +, and the simplest of all the chemical bonds is the one-electron bond.
The term 'molecular biology' was first used in 1945 by the English physicist William Astbury, who described it as an approach focused on discerning the underpinnings of biological phenomena—i.e. uncovering the physical and chemical structures and properties of biological molecules, as well as their interactions with other molecules and how ...
Organic compounds are molecules that contain carbon bonded to another element such as hydrogen. [33] With the exception of water, nearly all the molecules that make up each organism contain carbon. [ 33 ] [ 34 ] Carbon can form covalent bonds with up to four other atoms, enabling it to form diverse, large, and complex molecules.
Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life. [ 3 ] [ 63 ] Selenium acts as the catalytic center of several antioxidant enzymes, such as glutathione peroxidase , [ 11 ] and plays a wide variety of other biological roles .
Biomolecules and their reactions are studied in biology and its subfields of biochemistry and molecular biology. Most biomolecules are organic compounds, and just four elements—oxygen, carbon, hydrogen, and nitrogen—make up 96% of the human body's mass. But many other elements, such as the various biometals, are also present in small amounts.
Most rare elements on Earth are not needed by life (exceptions being selenium and iodine), [33] while a few common ones (aluminum and titanium) are not used. Most organisms share element needs, but there are a few differences between plants and animals. For example, ocean algae use bromine, but land plants and animals do not seem to need any.
Receptors and ligands exist in many different forms, and only recognize/bond to particular molecules. Upstream extracellular signaling transduce a variety of intracellular cascades. [1] Receptors and ligands are common upstream signaling molecules that dictate the downstream elements of the signal pathway. A plethora of different factors affect ...
Organic molecules on the early Earth could have had either terrestrial origins, with organic molecule synthesis driven by impact shocks or by other energy sources, such as ultraviolet light, redox coupling, or electrical discharges; or extraterrestrial origins (pseudo-panspermia), with organic molecules formed in interstellar dust clouds ...