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Title: What is the advantage of a cycle that can replenish itself? Post by: isabelle0604 on Dec 1, 2012 I am learning about photosynthesis and I think this question is about the calvin cycle.
But I really really don't get it.. It seems like I don't understand the question and other answers. Can someone explain this to me easily? What is the advantage of a cycle that can replenish itself? Title: Re: What is the advantage of a cycle that can replenish itself? Post by: ThePsychic on Dec 1, 2012 Under normal conditions, it has to replenish its ribulose biphosphate so it can carry on fixing more carbon dioxide. If this didn't occur, the latter process wouldn't occur.
Title: Re: What is the advantage of a cycle that can replenish itself? Post by: onequicklook on Dec 1, 2012 In the dark reactions, the two molecules of phosphoglyceric acid each gain another phosphate (breaking down two more molecules of ATP into ADP) becoming biphosphoglyceric acid. NADPH and the hydrogen ions made in the light reactions are used to split a phosphate off of each (putting phosphates back to make more ATP) and to provide the energy and hydrogen to turn the remaining chemical into glyceraldehyde phospate, also called phosphoglyceraldehyde, or PGAL. (The NADPH and H+ combine with the phosphoglyceric acid to make PGAL, leaving behind NADP+ which will go back to the light reactions to be transformed again.) PGAL is the raw material for anything a plant needs. PGAL can be used to make sugar and to replenish the ribulose phosphate stores, so that this reaction can happen again.
(http://www.compuhigh.com/demo/biology/lesson09_files/calvincyle.jpg) |