![]() The Chloroplast Is One Member of the Plastid Family of OrganellesĬhloroplasts are the most prominent members of the plastid family of organelles. Nevertheless, the fundamental mechanisms involved in light-driven ATP synthesis in chloroplasts are very similar to those that we have already discussed for respiration-driven ATP synthesis in mitochondria. The many differences between chloroplasts and mitochondria are thought to reflect their different bacterial ancestors, as well as their subsequent evolutionary divergence. Mitochondria are also generally believed to be descended from an endocytosed bacterium. In plants, the products include a low-molecular-weight sugar (usually sucrose) that is exported to meet the metabolic needs of the many nonphotosynthetic cells of the organism.īiochemical and genetic evidence strongly suggest that chloroplasts are descendants of oxygen-producing photosynthetic bacteria that were endocytosed and lived in symbiosis with primitive eucaryotic cells. The immediate products of photosynthesis, NADPH and ATP, are used by the photosynthetic cells to produce many organic molecules. Chloroplasts perform photosynthesis during the daylight hours. In plants and algae, which developed much later, photosynthesis occurs in a specialized intracellular organelle-the chloroplast. As we see in this section, it is thought that the evolution of cyanobacteria from more primitive photosynthetic bacteria eventually made possible the development of abundant aerobic life forms. (CH 2O) n + nO 2], they also liberate into the atmosphere the oxygen required for oxidative phosphorylation.
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