- Crenarchaeota
- Euryarchaeota
- Korarchaeota
- Nanoarchaeota
- Thaumarchaeota

Major Phylum of Archaea

Archaeal plasma membranes differ fundamentally from bacterial and eukaryotic membranes in three significant ways. First, archaeal membrane phospholipids are formed with ether linkages, rather than the ester linkages found in bacteria and eukaryotes. Second, archaeal phospholipids contain branched chains, whereas those of bacterial and eukaryotic cells are straight-chained. Finally, while some archaeal membranes form lipid bilayers similar to other domains, other archaeal plasma membranes exist as lipid monolayers.

Archaeal Plasma Membrane Structure

Archaeal cell wall structure differs from bacterial cell walls primarily because archaea do not contain peptidoglycan. Instead, they often contain a similar polymer called pseudopeptidoglycan (or pseudomurein). Alternatively, some archaea possess a layer of glycoproteins or polysaccharides that serves as the cell wall, and a few archaeal species appear to lack cell walls entirely.

Archaeal Cell Walls vs. Bacterial Cell Walls

Eukaryotic cells contain multiple, linear chromosomes that are haploid or diploid and are wrapped around histone proteins. In contrast, prokaryotes typically possess a single, circular chromosome that is haploid, with bacteria lacking histones and archaea containing histones.

Comparison of Eukaryotic and Prokaryotic Chromosomes

Archaea are unicellular prokaryotic organisms that have distinct evolutionary histories, genetics, metabolic pathways, and structural compositions compared to bacteria. They are found in nearly every habitat, including extreme environments that are very cold, hot, basic, or acidic. While some archaea reside in the human body, none have been identified as human pathogens.

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University of Wisconsin - Madison

A prokaryotic cell is a major category of cell that lacks a nucleus surrounded by a complex nuclear membrane. Instead, its genetic material is generally a single, circular chromosome located in a nucleoid region. While prokaryotic cells generally lack complex membrane-bound organelles, they often contain inclusions that compartmentalize their cytoplasm. Microorganisms composed of these cells are classified within the domains Archaea and Bacteria.

Prokaryotic Cell

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Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

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Bacteria are prokaryotic microorganisms found in nearly every habitat on Earth, including within and on the human body. As prokaryotes, their genetic material (DNA) is not housed within a true nucleus. Most bacterial cells feature cell walls containing peptidoglycan. While many bacteria are harmless or beneficial, some act as pathogens and cause diseases in humans and other animals.

Bacteria

Photosynthesis is the process of using the sun's light as energy and converting it to chemical energy to fix gaseous carbon dioxide and create sugars such as glucose. The first organisms with the capability to photosynthesize stemmed from prokaryotes 3.8 billion years ago. What is required for photosynthesis include a light source, carbon, electron donor, and pigments to harvest energy.

Photosynthesis

Bacteria is a very diverse domain, characterized by their prokaryotic cells and lack of ether linkages, with membranes made of phospholipid bilayers.

Bacteria (domain)

Archaea

The cell envelope is a collective term for the structural layers that enclose the cytoplasm and internal components of a cell. In prokaryotic organisms, the precise composition of the cell envelope varies depending on the species and cell type, but it universally includes a plasma membrane and, in the vast majority of cases, a surrounding cell wall.

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