Carotenoids - Definition, Function and Types | Biology Dictionary

Carotenoids Definition and FunctionCarotenoids are a type of accessory pigment, created by plants to help them absorb light energy and convert it to chemical energy. There are two types of carotenoids, xanthophylls and carotenes, which differ only in their oxygen content. Carotenoids have a similar base structure consisting of 8 isoprene molecules. Isoprene molecules have 5 carbons, and 8 of them together has 40 carbons. All carotenoids share this structure, and as such are also called tetraterpenoids.Accessory pigments like the carotenoids are used for a variety of reasons in plants. Some are used to collect different wavelengths of light than the primary pigment, chlorophyll. Other carotenoids are used to take energy from chlorophyll as it becomes excited by light, and pass the energy down the chain. While leaves typically appear green because of the abundance of green chlorophyll, they will turn red and brown in the fall. This is because the chlorophyll degrades as there is less lig...