a capsule which (like those of pneumococci) makes it resistant to phagocytosis.Its 2 plasmids contain the genes needed to synthesize Currently the biological agent favored by terrorists.
These organisms differ mainly in the plasmids they contain.
Bacillus anthracis/cereus/thuringiensis. More recently, genome sequencing, especially of their 16S ribosomal RNA (rRNA), has provided additional insights into the evolutionary relationships among the bacteria. Bacteria that are not decolorized by the alcohol/acetone wash are Gram-positive.Īlthough the Gram stain might seem an arbitrary criterion to use in bacterial taxonomy, it does, in fact, distinguish between two fundamentally different kinds of bacterial cell walls and reflects a natural division among the bacteria. To see them now requires the use of a counterstain of a different color (e.g., the pink of safranin). This washes the stain out of Gram-negative cells. Then the preparation is treated with alcohol or acetone. The bacterial cells are first stained with a purple dye called crystal violet. The outermost layer contains lipopolysaccharide (LPS). Gram-negative bacteria are encased in a triple-layer. Gram-positive bacteria are encased in a plasma membrane covered with a thick wall of peptidoglycan. method of energy production (glycolysis for anaerobes, cellular respiration for aerobes)įigure 19.2.1.1 Gram positive and negative bacteria. Until recently classification has done on the basis of such traits as: Spores are so resistant to adverse conditions of dryness and temperature that they may remain viable even after 50 years of dormancy. Most of the water is removed from the spore and metabolism ceases. Many bacteria form a single spore when their food supply runs low. Any sexual reproduction very different from that of eukaryotes no meiosis. 
The plasma membrane (in Gram-positive bacteria) and both membranes in Gram-negative bacteria are phospholipid bilayers but contain no cholesterol or other steroids.Have a rigid cell wall made of peptidoglycan.Ribosomes differ in their structure from those of eukaryotes.If flagella are present, they are made of a single filament of the protein flagellin there are none of the "9+2" tubulin-containing microtubules of the eukaryotes.prokaryotic (no membrane-enclosed nucleus).
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