4 BIO 326R Cell structure 2

4 BIO 326R Cell structure 2 - Bio 326R Cell Structure 2...

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Bio 326R Cell Structure 2
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Motility It’s actually more difficult (energetically) to move as body size decreases Despite this, they are (relatively) very fast: Bacteria can move at up to 100 body lengths per second. A cheetah running at 100 body lengths (7 feet) per second would travel at about 477 mph
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E. coli Flagella  L P S M Rings Hook Filament made by self assembly of flagellin Flagellin is the H in O157:H7 The flagella is a hollow tube structure, evolved from protein secretion machinery. Flagellin monomers enter the tube in the cytoplasm, travel through the tube and add on at the tip. Several rings are found near the base of the flagella and are (mostly) named for the portion of the cell they associate with: L – LPS/lipoprotein P – peptidoglycan S – M – membrane C – cytoplasm ATP-dependent motor proteins are found in the cytoplasm associated with the C and M rings C
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Flagella Monotrichous (one flagella) or peritrichous, atrichous, etc Can rotate clockwise or counterclockwise E. coli is multitrichous, but the flagella are all located at one end of the bacterium. The direction of the spin of the flagella controls movement CCW: forward CW: tumble
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Pili Pili usually have a spiral structure with a central pore. Adhesins are proteins found at the tip of the pili. They are specialized for attaching to various substrates. Cells will Attachment – to other bacteria, teeth, rocks, intestines… There are multiple adhesins. The adhesin protein can be changed to attach to a given surface. The pili has a modular structure Adhesion is often a crucial factor in the ability of a bacteria to cause disease Mating – some pili are essential for bacterial conjugation. Periplasmic space/cell wall outer membrane cytoplasmic membrane adhesin linkers Usher proteins Central pore
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Copyright ©2000 by the National Academy of Sciences Saulino, Evan T. et al. (2000) Proc. Natl. Acad. Sci. USA 97, 9240-9245
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Type III secretion system Type III secretion systems (TTSS) are found in many gram negative bacteria, including E. coli. They serve to translocate proteins into eukaryotic host cells They are morphologically and genetically similar to flagella – a long hollow structure emerging from the cell surface One important example is that found in the E. coli strain O157:H7, also
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This note was uploaded on 04/09/2009 for the course BIO 326R taught by Professor Whiteley during the Spring '08 term at University of Texas.

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4 BIO 326R Cell structure 2 - Bio 326R Cell Structure 2...

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