BIOL240 Lecture Notes - Lecture 3: Halobacterium Salinarum, Nanoarchaeum Equitans, Ignicoccus
16 Nov 2016
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Learning objectives: an introduction to the morphology, structure and diversity of archaea. Archaea, as a group, was only recognized as a separate domain of life at the end of the. After comparing ribosomal rna sequences however, it was determined that they were in a distinct domain. Archaeal dna exists, like bacteria, as a single circular chromosome. Dna-binding proteins, called histones, which exist in eukaryotes as well. (figure 4. 5) All archaeons possess a plasma membrane and mos t also have a cell wall. The chemical composition of the archaeal cell envelope is significantly different from the other two domains. There are important differences between the lipids in bacteria and the lipids in archaea. As illustrated in figure 4. 7, archaeal lipids have ether linkages (increased stability), while bacterial lipids have ester linkages. Although archaeal organisms do not have peptidoglycan walls, many ha ve a wall constructed of a similar material called pseudomurein (or sometimes pseudopeptidoglycan).
