Structure of Bacterial cell - Karachi King's School ... Structure of Bacterial cell Badil Lecturer
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Transcript of Structure of Bacterial cell - Karachi King's School ... Structure of Bacterial cell Badil Lecturer
Structure of Bacterial cell
�Flagella �Pili �Capsule �Plasma Membrane �Cytoplasm�Cytoplasm �Cell Wall �Lipopolysaccharides �Teichoic Acids �Inclusions �Spores
� Motility – movement Arrangement basis for classification Monotrichous; 1
flagella ◦ Monotrichous 1 flagella ◦ Lophotrichous tuft at one end◦ Lophotrichous tuft at one end ◦ Amphitrichous both ends ◦ Peritrichous all around bacteria
� Short protein appendages
◦ smaller than flagella � Adhere bacteria to surfaces �� Used in conjugation for Exchange of genetic Used in conjugation for Exchange of genetic
� Glycocalyx - Polysaccharide on external surface � Adhere bacteria to surface � Prevents Phagocytosis
� Bilayer Phospholipid � Water can penetrate � Flexible � Not strong, ruptures easily
� Peptidoglycan Polymer (amino acids + sugars) � Prevents osmotic rupture � Some antibiotics effect directly ◦ Penicillin
� Glycerol, Phosphates, & Ribitol � Attachment for Phages
� Endotoxin or Pyrogen ◦ Fever causing
� Structure ◦ Lipid A ◦ Polysaccharide◦ Polysaccharide
◦◦ Form endospore whenever when habitat conditions become Form endospore whenever when habitat conditions become harsh (little food)harsh (little food) ◦◦ Able to survive for long periods of time Able to survive for long periods of time ◦◦ Difficult to destroy (heat resistant)Difficult to destroy (heat resistant)
� Bacterial DNA is circular and arrayed in a region of the cell known as the nucleotide .
� Scattered within bacteria’s inner membrane are numerous small loops of DNA known as plasmidsnumerous small loops of DNA known as plasmids
�� Prokaryotic cell division is binary fission. Prokaryotic cell division is binary fission.
◦◦ Single DNA molecule that first replicates.Single DNA molecule that first replicates.
◦◦ Attaches each copy to a different part of the cell membrane. Attaches each copy to a different part of the cell membrane.
◦◦ Cell begins to pull apart.Cell begins to pull apart.
◦◦ Following cytokinesis, there are then two cells of identical genetic Following cytokinesis, there are then two cells of identical genetic compositioncomposition
� G+ ◦ Thicker cell wall ◦ Teichoic Acids
� G-� G- ◦ Endotoxin - LPS
Gram-Negative Bacteria Gram-Positive Bacteria
More complex cell wall. Simple cell wall.
Thin peptidoglycan cell wall Thick peptidoglycan cell wall Thin peptidoglycan cell wall layer.
Thick peptidoglycan cell wall layer.
Outer lipopolysaccharide wall layer.
No outer lipopolysaccharide wall layer.
Retain safranin. Retain crystal violet/iodine.
Appear pink/red. Appear blue/purple.