Gen Bio II- Prokaryotes Notes

Transfers while it replicates one of a few mechanisms

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Unformatted text preview: andom –  Counterclockwise: Run –  Clockwise: Tumble •  Bacteria move in response to sDmuli (taxis) –  Towards chemical gradient Figure 3.45 Pearson EducaDon External Structures of Bacterial Cells •  Fimbriae –  SDcky, bristle like projecDons –  Shorter than flagella –  Contain adhesin –  Twitching moDlity –  Mediate a_achment to substances in environment –  Adherence o`en the iniDal step of persistent infecDon 5 1/29/14 Fimbriae Mabck 2002 Pili •  Tubules composed of pilin •  Also known as conjugaDon pili •  Longer than fimbriae but shorter than flagella •  Not universal –  Absent in Gram posiDves •  Mediate the transfer of DNA from one cell to another (conjugaDon) –  Donor/recipient –  Transfers while it replicates –  One of a few mechanisms bacteria can exchange geneDc material Bacteria Cell Structure •  External structures –  –  –  –  –  Capsules Slime layer Flagella Fimbriae, Pili •  Cell envelope –  Cell membrane –  Cell wall •  Cytoplasm –  No membrane bound organelles –  Endospores –  Nucleoid –  Ribosomes 6 1/29/14 Bacterial Cytoplasmic Membranes •  Referred to as phospholipid bilayer –  Composed of lipids and associated proteins •  Fluid mosaic model •  Gram negaDve has inner and outer membrane Bacterial Cell Walls •  Two basic types –  Gram- posiDve and Gram- negaDve •  Composed of pepDdoglycan •  Provide structure and shape and protect cell from osmoDc forces •  Protects against some anDmicrobial drugs –  Targeted by others 7 1/29/14 NAG and NAM Pearson EducaDon PepDdoglycan Glycans PepDdes Gram- posiDve Bacterial Cell Walls •  RelaDvely thick layer of pepDdoglycan •  Contain unique polya...
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