Pseudopeptidoglycan in the context of "Lysozyme"

A cell wall is a structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. Another vital role of the cell wall is to help the cell withstand osmotic pressure and mechanical stress. While absent in many eukaryotes, including animals, cell walls are prevalent in other organisms such as fungi, algae and plants, and are commonly found in most prokaryotes, with the exception of mollicute bacteria.

The composition of cell walls varies across taxonomic groups, species, cell type, and the cell cycle. In land plants, the primary cell wall comprises polysaccharides like cellulose, hemicelluloses, and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae exhibit cell walls composed of glycoproteins and polysaccharides, such as carrageenan and agar, distinct from those in land plants. Bacterial cell walls contain peptidoglycan, while archaeal cell walls vary in composition, potentially consisting of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls constructed from the polymer chitin, specifically N-acetylglucosamine. Diatoms have a unique cell wall composed of biogenic silica.

Otto Kandler (23 October 1920 in Deggendorf – 29 August 2017 in Munich, Bavaria) was a German botanist and microbiologist. Until his retirement in 1986 he was professor of botany at the Ludwig Maximilian University of Munich.

His most important research topics were photosynthesis, plant carbohydrate metabolism, analysis of the structure of bacterial cell walls (murein/peptidoglycan), the systematics of Lactobacillus, and the chemotaxonomy of plants and microorganisms.He presented the first experimental evidence for the existence of photophosphorylation in vivo. His discovery of the basic differences between the cell walls of bacteria and archaea (up to 1990 called "archaebacteria") convinced him that archaea represent an autonomous group of organisms distinct from bacteria. This was the basis for his cooperation with Carl Woese and made him the founder of research on the Archaea in Germany. In 1990, together with Woese, he proposed the three domains of life: Bacteria, Archaea, Eucarya. Finally, on the basis of his lifelong interest in the early evolution and diversification of life on this planet, Kandler presented his pre-cell theory, suggesting that the three domains of life did not emerge from an ancestral cell, e.g. the last universal common ancestor (LUCA), but from a population of pre-cells.

A cell wall is a structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. Another vital role of the cell wall is to help the cell withstand osmotic pressure and mechanical stress. Cell walls are found in most prokaryotes, with the exception of mollicute bacteria. Among the eukaryotes, cells walls are prevalent in fungi, algae and plants but absent from animals and many other taxa.

The composition of cell walls varies across taxonomic groups, species, cell type, and the cell cycle. In land plants, the primary cell wall comprises polysaccharides like cellulose, hemicelluloses, and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae exhibit cell walls composed of glycoproteins and polysaccharides, such as carrageenan and agar, distinct from those in land plants. Bacterial cell walls contain peptidoglycan, while archaeal cell walls vary in composition, potentially consisting of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls constructed from the polymer chitin, specifically N-acetylglucosamine. Diatoms have a unique cell wall composed of biogenic silica.