molecule

Examples of molecule in the following topics:

• Homonuclear Diatomic Molecules

  • Diatomic molecules are composed of only two atoms, of either the same or different chemical elements.
  • Common diatomic molecules include hydrogen (H2), nitrogen (N2), oxygen (O2), and carbon monoxide (CO).
  • All diatomic molecules are linear, which is the simplest spatial arrangement of atoms.
  • Translational energies (the molecule moving from point A to point B)
  • A space-filling model of the homonuclear diatomic molecule nitrogen.

• Molecules

  • Most often, the term "molecules" refers to multiple atoms; a molecule may be composed of a single chemical element, as with oxygen (O2), or of multiple elements, such as water (H2O).
  • Most molecules are too small to be seen with the naked eye.
  • The full elemental composition of a molecule can be precisely represented by its molecular formula, which indicates the exact number of atoms that are in the molecule.
  • Isomers are molecules with the same atoms in different geometric arrangements.
  • Each molecule is a structural isomer of the other.

• Polyatomic Molecules

  • A polyatomic molecule is a single entity composed of at least three covalently-bonded atoms.
  • Molecules are distinguished from ions by their lack of electrical charge.
  • The science of molecules is called molecular chemistry or molecular physics, depending on the focus.
  • A pure substance is composed of molecules with the same average geometrical structure.
  • Molecules with the same atoms in different arrangements are called isomers.

• Metabolic Pathways

  • An anabolic pathway requires energy and builds molecules while a catabolic pathway produces energy and breaks down molecules.
  • Another metabolic pathway might build glucose into large carbohydrate molecules for storage.
  • Catabolic pathways involve the degradation of complex molecules into simpler ones, releasing the chemical energy stored in the bonds of those molecules.
  • Anabolic pathways are those that require energy to synthesize larger molecules.
  • Catabolic pathways are those that generate energy by breaking down larger molecules.

• Outcomes of Glycolysis

  • One glucose molecule produces four ATP, two NADH, and two pyruvate molecules during glycolysis.
  • Glycolysis starts with one molecule of glucose and ends with two pyruvate (pyruvic acid) molecules, a total of four ATP molecules, and two molecules of NADH .
  • Two ATP molecules were used in the first half of the pathway to prepare the six-carbon ring for cleavage, so the cell has a net gain of two ATP molecules and 2 NADH molecules for its use.
  • If the cell cannot catabolize the pyruvate molecules further (via the citric acid cycle or Krebs cycle), it will harvest only two ATP molecules from one molecule of glucose.
  • In this situation, the entire glycolysis pathway will continue to proceed, but only two ATP molecules will be made in the second half (instead of the usual four ATP molecules).

• Water’s Solvent Properties

  • Water's polarity makes it an excellent solvent for other polar molecules and ions.
  • A polar molecule with partially-positive and negative charges, it readily dissolves ions and polar molecules.
  • The charges associated with these molecules form hydrogen bonds with water, surrounding the particle with water molecules.
  • Water is a poor solvent, however, for hydrophobic molecules such as lipids.
  • Nonpolar molecules experience hydrophobic interactions in water: the water changes its hydrogen bonding patterns around the hydrophobic molecules to produce a cage-like structure called a clathrate.

• Riboswitches

  • Riboswitches are naturally occurring RNA molecules that can regulate gene expression.
  • Riboswitches are specific components of an mRNA molecule that regulates gene expression.
  • The riboswitch is a part of an mRNA molecule that can bind and target small target molecules.
  • An mRNA molecule may contain a riboswitch that directly regulates its own expression.
  • Hence, the existence of RNA molecules provide evidence to the RNA world hypothesis that RNA molecules were the original molecules, and that proteins developed later in evolution.

• Molecules in Biological Membranes

• More complex organic molecules and life

• Dipole-Dipole Force

  • Molecules that contain dipoles are called polar molecules and are very abundant in nature.
  • A dipole is a molecule that has split charge.
  • The negatively charged oxygen atom of one molecule attracts the positively charged hydrogen of another molecule.
  • Attractions between polar molecules vary.
  • Choose a pair of molecules from the drop-down menu and "pull" on the star to separate the molecules.