CH 461 Lecture Notes - Lecture 13: Triosephosphate Isomerase, Phosphate, C3 Carbon Fixation
Document Summary
The atp and nadph from the light reactions are used for making the acceptors and converting the first products into glucose. The dark reactions use atp and nadph to convert co 2 into carbohydrate. The first step is fixing co 2 into organic carbon. The basic reaction is addition of co 2 to a phosphorylated acceptor. This step requires no direct input of energy. Two types of plants exist, which use different acceptor molecules. In so called c 3 plants, the acceptor is a 5 carbon, doubly phosphorylated acceptor, and two 3 carbon phosphorylated compounds are formed. In c 4 plants, the acceptor is phosphoenolpyruvate, and the carboxylation makes the 4 carbon acid oxaloacetatic. This pathway is sometimes called the calvin benson cycle, after the biochemists who elucidated it. The 5 carbon, doubly phosphorylated carbohydrate, ribulose bisphosphate is the acceptor for co 2; the enzyme is called ribulose bisphosphate.
