Microbial Physiology notes lec7 10-8-10

It anchors by converting from a swarm cell into an

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it anchors by converting from a swarm cell into an stalked cell it’s a part of cell cycle—it converts from a swarm cell into a stalked cell -stalked cell cant convert into a swarm cell, as a result of the morphological and differential properties, it takes longer for a swarm cell to undergo another division than a stalk cell, it takes a swarm cell ~ 40mins longer -want to sync cell division, but cant do it because the ½ of the population ( swarm cell ) takes 40 mins longer than other ½ stalked cells to divide -at the end of the stalk cell, are molecules of adhesion that sticks to anything solid that bacterium finds appropriate, it can also stick to other caulobacter to form a rosette of cells with the stalk in the middle w/ the adhesive end they are having group sex -The 2 poles exhibit differential: 1. DNA condensation: -condensation of DNA if found during sporulation, the mother cell’s DNA retains a relaxed chromosome, but the pre-spore begins to condense its DNA so it becomes a very compact structure that stabilizes the DNA within that compact structure In swarm cell, the DNA is partially condensed, so its compacted and therefore not all available for txn that is part of the mechanism in which it differentiates into a different direction into a stalked cell 2. Replication capacity -swarm cell cant replicate until its DNA comes out of the condensed state -txn of certain genes are inhibited, but the entire replication process is restricted because some of the DNA is compacted into histone like proteins are tightly compacted with it and cant dissociate them normally 3. Txn -have different genes transcribes at the 2 poles and continue to make materials in the stalk half, and the swarm cell makes flagella, and Chemotaxis receptors that get methylated, and Chemotaxis proteins, and pili
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-pillus for a bacteria is organelles of adhesion for the swarm cells, that no longer have a stalk, so it makes pilli, and when it finally attaches to something, then it destroys the protein on the inner surface of the cell that has anything to do w/ pillus structure or flagella, or Chemotaxis fxn the flagella outer part just falls off, and it becomes a stalk cell and stays at that site swarm cell gene expression is temporally controlled 4. mRNA or protein targeting Different genes are transcribed at different poles of the cell 5. Assembly and modification of complexes at the proper poles 6. Protein degradation - if a caulobacter protein that should be at the swarm pole goes accidentally to stalk cell it gets rapidly degraded so there is some signal or spatial degradation via proteasome that’s ATP dependent
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  • Fall '10
  • Saier
  • DNA, swarm cell

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