Lycopene the structure of the molecule was determined by 1931. In its natural, all-"trans" form, the molecule is long and straight, constrained by its system of 11 conjugated double bonds. Each extension in this conjugated system reduces the energy required for electrons to transition to higher energy states, allowing the molecule to absorb visible light of progressively longer wavelengths. Lycopene absorbs all but the longest wavelengths of visible light, so it appears red. Plants and photosynthetic bacteria naturally produce all-"trans" lycopene. When exposed to light or heat, lycopene can undergo isomerization to any of a number of "cis"-isomers, which have a
Self colour the tip. The term can also be used to distinguish between colour and pattern; patterns are unpigmented areas with pink skin and white hair. In this definition, an animal has only one self-colour, which is the sum effect of all the genes acting on the pigment. For example, a black and tan piebald Dachshund has patterns (piebald) and self-colours (black and tan). Self colour A self colour refers to the top coat colouration of several domestic animals, such as dogs, pet rodents and cats. It refers to hairs of a uniform shade, with no banding or tipping of another colour.