News tagged with molecules

Related topics: cells , protein , atoms , cancer cells , cancer

Single enzyme is necessary for development of diabetes

An enzyme called 12-LO promotes the obesity-induced oxidative stress in the pancreatic cells that leads to pre-diabetes, and diabetes. 12-LO's enzymatic action is the last step in the production of certain small molecules ...

Aug 14, 2014
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A new player in lipid metabolism discovered

(Medical Xpress)—Specially engineered mice that lacked a particular gene did not gain weight when fed a typical high-fat, obesity-inducing Western diet. Yet, these mice ate the same amount as their normal ...

Aug 05, 2014
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Small RNAs in blood may reveal heart injury

(Medical Xpress)—Like clues to a crime, specific molecules in the body can hint at exposure to toxins, infectious agents or even trauma, and so help doctors determine whether and how to treat a patient. ...

Aug 01, 2014
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Are human genes patentable?

(Medical Xpress)—On April 15, the Supreme Court will hear oral argument in Association for Molecular Pathology v. Myriad Genetics, a case that could answer the question, "Under what conditions, if any, ...

Apr 11, 2013
popularity 4.3 / 5 (6) | comments 16 | with audio podcast

Molecule

A molecule is defined as a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense. In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules.

In the kinetic theory of gases the term molecule is often used for any gaseous particle regardless of its composition. According to this definition noble gas atoms are considered molecules despite the fact that they are composed of a single non-bonded atom.

A molecule may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O). Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules.

No typical molecule can be defined for ionic crystals (salts) and covalent crystals (network solids), although these are often composed of repeating unit cells that extend either in a plane (such as in graphene) or three-dimensionally (such as in diamond or sodium chloride). The theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding. In glasses (solids that exist in a vitreous disordered state), atoms may also be held together by chemical bonds without any definable molecule, but also without any of the regularity of repeating units that characterises crystals.

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