Amoeba may offer key clue to photosynthetic evolution
The major difference between plant and animal cells is the photosynthetic process, which converts light energy into chemical energy. When light isnt available, energy is generated by breaking down carbohydrates and sugars, just as it is in animal and some bacterial cells. Two cellular organelles are responsible for these two processes: the chloroplasts for photosynthesis and the mitochondria for sugar breakdown. New research from Carnegies Eva Nowack and Arthur Grossman has opened a window into the early stages of chloroplast evolution. Their work is published online by the Proceedings of the National Academy of Sciences in the week of February 27-March 2. It is widely accepted that chloroplasts originated from photosynthetic, single-celled bacteria called cyanobacteria, which were engulfed by a more complex, non-photosynthetic cell more than 1.5 billion years ago. While the relationship between the two organisms was originally symbiotic, over evolutionary time the cyanobacterium transferred most of its genetic information to the nucleus of the host organism, transforming the original cyanobacterium into a chloroplast that is no longer able to survive without its host.
