Flagellar ultrastructure Filament: from cell surface to the tip Basal body: embedded in the cell Hook: link the filament to its basal body Basal body The e coli Flagellar G s(peptidoglycan) Structure Mplasma membrane G L(out membrane) P(peptidoglycan layer) S-M(contact the plasma membrane)
Flagellar ultrastructure Filament: from cell surface to the tip Basal body: embedded in the cell Hook: link the filament to its basal body Basal body: G+ : S (peptidoglycan), M(plasma membrane) G-: L (out membrane), P (peptidoglycan layer), S-M(contact the plasma membrane) The E. coli Flagellar Structure
Bacterial behavior Chemotaxis phototaxis. and other taxes Prokaryotes encounter gradients of physical and chemical agents in nature, and the motility machinery in the cell is designed to respond in a positive or negative way to these gradients by directing the movement of the cell either toward or away from the signal molecule, respectively Such directed movements are called taXes Chemotaxis: a response to chemicals Phototaxis: a response to light
Bacterial Behavior Chemotaxis, Phototaxis, and Other Taxes • Prokaryotes encounter gradients of physical and chemical agents in nature, and the motility machinery in the cell is designed to respond in a positive or negative way to these gradients by directing the movement of the cell either toward or away from the signal molecule, respectively. • Such directed movements are called TAXES. • Chemotaxis: a response to chemicals. • Phototaxis: a response to light
How to iudge wether a cell have flagella 1. Light Microscope by staining 2. Electron microscope 3. Feature of colony 4, Culture in semi-solid medium
How to judge wether a cell have flagella • 1. Light Microscope by staining • 2. Electron microscope • 3. Feature of colony • 4. Culture in semi-solid medium
Endospore structure DNA 82sEo王 Mature free endospore
Endospore Structure Mature free endospore
Spore formation: lack of nutrients. 7 stages End of Asymmetric Endocytosis or engulfment of daughter protoplast vegetative growth septation 000 Steps in endospore formation Lysis of mother cell Assembly of Synthesis of and release of proteinaceous peptidoglycan-containing SPORE spore coat cortex
Spore formation: lack of nutrients. 7 stages