What is Chirality?
[[File:Chirality with hands.svg|300px|thumb|Two enantiomers of a generic [[amino acid]]]] [[File:Chiral.svg|right|thumbnail|250px|The two enantiomers of bromochlorofluoromethane]] '''Chirality''' is when an object is present in two forms which are mirror images of each other.<ref>The word ''chiral'' is derived from the Greek word for hand, χειρ (/cheir/).</ref> The two forms cannot be superimposed. Human [[hand]]s are chiral. The left hand is a mirror image of the right hand. You cannot turn or move one of your hands to look exactly the same as the other. This is why you can not put a left handed [[glove]] on your right hand, or shake the right hand of a person using your left hand. == In chemistry == In [[chemistry]], chirality refers to [[molecule]]s. If a molecule is chiral it has two forms that are mirror images of each other but ''otherwise identical''. Chemists call these ''[[enantiomer]]s'' or ''optical [[isomer]]s''. Because the difference between right and left hands is easy to understand, chemists call enantiomers either '[[right-handed|right-]]' or '[[left-handed]]'. A mixture of equal amounts of the two enantiomers is called a ''racemic mixture''. Molecular chirality is quite common. It is found in [[stereochemistry]], [[inorganic chemistry]], [[organic chemistry]], [[physical chemistry]], and [[biochemistry]]. The [[symmetry]] of a molecule (or any other object) tells us whether it is chiral. A molecule is ''achiral'' (not chiral) if it has an axis of symmetry. === Racemic mixtures === A '''racemic''' mixture is one which has equal amounts of left- and right-handed enantiomers of a chiral molecule. == Homochiralism in biology == Many biologically active molecules are chiral, including [[amino acid]]s (the building blocks of [[protein]]s) and [[sugar]]s. Most of these compounds are of the same chirality. Most amino acids are <small>L</small> (left-handed) and sugars are <small>D</small>. (right-handed). Proteins made of <small>L</small> amino acids, are known as ''left-handed proteins'', wher