man rha abe O-antigen repeat 40 units Core polysaccharide Disaccharide O HN O HN diphosphate Lipid A Fatty acids Structure of Lipopolysaccharide
The mechanism of Gram staining During the procedure the bacteria are first stained with crystal violet and next treated with iodine to promote dye retention. When gram-positive bacteria then are decolorized with ethanol, the alcohol is thought to shrink the pores ofthe thick peptidoglycan. Thus the dye-iodine complex is retained during the short decolorization step and the bacteria remain purple. In contrast, gram-negative bacteria peptidoglycan is very thin, not as highly cross-linked, and has larger pores Alcohol treatment also may extract enough lipid from the gram-neaative wall to increase its porosity further: For these reasons, alcohol more readily removes the purple crystal violet-iodine complex from gram-negative bacteria
The mechanism of Gram staining During the procedure the bacteria are first stained with crystal violet and next treated with iodine to promote dye retention. When gram-positive bacteria then are decolorized with ethanol, the alcohol is thought to shrink the pores of the thick peptidoglycan. Thus the dye-iodine complex is retained during the short decolorization step and the bacteria remain purple. In contrast, gram-negative bacteria peptidoglycan is very thin, not as highly cross-linked, and has larger pores. Alcohol treatment also may extract enough lipid from the gram-neaative wall to increase its porosity further. For these reasons, alcohol more readily removes the purple crystal violet-iodine complex from gram-negative bacteria
Chapter 1 The structure and function of prokaryotes Special structure Pili and fimbriae Flagella The bacterial endospore
Special structure • Pili and fimbriae • Flagella • The bacterial endospore Chapter 1 The structure and function of prokaryotes
Pili and fimbriae G", short, fine, hairlike appendages that are not involved in motility Fimbriae/fimbria: 1000piece/cell, adhesion to host epithelium Sex pili/pilus: 1-10piece/cell, sexual conjugation, they are genetically determined by sex factors or conjugative plasmids and are required for bacterial mating. Receptors of some bacterial viruses
Pili and fimbriae G-, short, fine, hairlike appendages that are not involved in motility. Fimbriae/fimbria:1000piece/cell, adhesion to host epithelium Sex pili/pilus: 1-10piece/cell, sexual conjugation, they are genetically determined by sex factors or conjugative plasmids and are required for bacterial mating. Receptors of some bacterial viruses
Flagellar arrangements Peritrichous Polar/monotrichous Lophotrichous Amphitrichous
Flagellar Arrangements Amphitrichous Peritrichous Polar/monotrichous Lophotrichous