Search results
Results from the WOW.Com Content Network
Many structural features are unique to bacteria and are not found among archaea or eukaryotes. Because of the simplicity of bacteria relative to larger organisms and the ease with which they can be manipulated experimentally, the cell structure of bacteria has been well studied, revealing many biochemical principles that have been subsequently ...
The aromatic/arginine or "ar/R" selectivity filter is a cluster of amino acids that help bind to water molecules and exclude other molecules that may try to enter the pore. It is the mechanism by which the aquaporin is able to selectively bind water molecules and so to allow them through, and to prevent other molecules from entering.
In gram-negative bacteria, the inner membrane is the major permeability barrier. [10] The outer membrane is more permeable to hydrophilic substances, due to the presence of porins. [5] Porins have threshold sizes of transportable molecules that depend on the type of bacteria and porin.
These bacteria are commonly found in iron and manganese deposits on surfaces exposed intermittently to plumes of hydrothermal and bottom seawater. However, due to the rapid oxidation of Fe 2+ in neutral and alkaline waters (i.e. freshwater and seawater), bacteria responsible for the oxidative deposition of iron would be more commonly found in ...
Food vacuoles (also called digestive vacuole [28]) are organelles found in Ciliates, and Plasmodium falciparum, a protozoan parasite that causes Malaria. Histopathology In histopathology , vacuolization is the formation of vacuoles or vacuole-like structures, within or adjacent to cells.
Capsules allow adhesion to surfaces and help enable the bacteria to evade the host immune system. [6] The water content in the capsule gives the protection against drying out. The capsule is considered a virulence factor because it enhances the ability of bacteria to cause disease (e.g. prevents phagocytosis).
The antibiotic penicillin is able to kill bacteria by preventing the cross-linking of peptidoglycan and this causes the cell wall to weaken and lyse. [37] The lysozyme enzyme can also damage bacterial cell walls. There are broadly speaking two different types of cell wall in bacteria, called gram-positive and gram-negative.
Another example is soap, which has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both water and oil. Hydrophilic and hydrophobic molecules are also known as polar molecules and nonpolar molecules, respectively. Some hydrophilic substances do not dissolve. This type of mixture is called a colloid.