ExternalStructures:Appendages- Two major groups of appendages: Motility - flagella and axial filaments(periplasmic flagella): Attachment or channels -fimbriae and pili? Glycocalyx - surface coating6
6 External Structures • Appendages – Two major groups of appendages: • Motility – flagella and axial filaments (periplasmic flagella) • Attachment or channels – fimbriae and pili • Glycocalyx – surface coating
Flagella: 3 parts:- Filament - long, thin, helical structure composed ofprotein flagellin-Hook-curved sheath- Basal body - stack of rings firmly anchored in cell wallCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or displayFilamentHook-Outer/Lringmembrane价价CellwallBasalPeriplasmiRod>RingsbodyspaceRingsTCell7membrane(b)(a)22nm
Hook Filament Periplasmic space L ring Cell wall Cell membrane Rod Rings Outer membrane Basal body (a) 22 nm (b) Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display. Rings 7 Flagella • 3 parts: – Filament – long, thin, helical structure composed of protein flagellin – Hook – curved sheath – Basal body – stack of rings firmly anchored in cell wall
FlagellaRotates 360Functions in motility of cell through environmentCopyright The McGraw-Hil Companies, Inc. Permission required for reproduction or display(a)(c)8(b)
(a) (b) (c) Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display. 8 Flagella • Rotates 360o • Functions in motility of cell through environment 8
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FlagellarArrangementsMonotrichousCopyagtt@TheMcGraw-Hill Comparonrequredforreproducbonordspiaysingle flagellumat one endLophotrichous -small bunchesemerging fromthe same site(a)(CAmphitrichous-flagella at bothends of cellPeritrichous -flagella(b)(d)dispersed oversurface of cell18
10 Flagellar Arrangements Monotrichous – single flagellum at one end Lophotrichous – small bunches emerging from the same site Amphitrichous – flagella at both ends of cell Peritrichous – flagella dispersed over surface of cell 10