17: Prokaryotes
- Page ID
- 123985
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Most organisms on Earth, and in fact most of the cells in your body, are prokaryotic. These unicellular organisms are ubiquitous across ecosystems and organisms, involved in every aspect of ecology. Prokaryotes can be divided into two major groups: Bacteria and Archaea. Unlike prokaryotes, viruses are acellular, and so are not considered living. However, they are distinct biological entities with important roles in evolutionary history and the life histories of organisms.
- 17.1: Prokaryotes
- This chapter will examine the diversity, structure, and function of prokaryotes. Prokaryotes have an important role in changing, shaping, and sustaining the entire biosphere. They can produce proteins and other substances used by molecular biologists in basic research and in medicine and industry
- 17.2: Bacteria
- Bacteria are a diverse group of organisms, ubiquitous on planet Earth. These prokaryotes have many important ecological roles, diverse metabolic strategies, and symbiotic relationships with plants. Bacteria were the biosphere's first photosynthesizers.
- 17.3: Cyanobacteria
- Cyanobacteria are a group of bacteria that perform oxygenic photosynthesis. The ancestors of modern cyanobacteria were responsible for the initial input of large amounts of oxygen into Earth's atmosphere. Evidence of these early cyanobacteria can be found in fossilized structures called stromatolites, which are still formed in some regions of the world. Cyanobacteria can be found free-living or as mutualists within the tissues of other organisms.
- 17.4: Root Nodules
- Some plants form a mutualistic relationship with bacteria for access to nitrogen. The bacteria infect the root hairs of the plant, forming a nodule. Within the nodule, the bacteria converts atmosperic nitrogen to a plant-available form. In return, the plant supplies the bacteria in the nodule with sugars.
- 17.5: Chapter Summary
- A summary of the chapter concepts.
Attributions
Chapter thumbnail artwork by Nikki Harris CC BY-NC