Prokaryote cell biology 1

• when was gram staining invented

  1884
• what colour is gram positive

  purple
• what colour is gram negative

  pink
• what do cell walls contain

  peptidoglucanmurein - consisting of N-acetylglucosamine and N-acetylmuramic acid that are cross-linked by a tetrapeptide
• what do gram negative cell walls contain

  an additional outer biomembrane; this generates a periplasmic space between both membranes
• what is an organelle

  A structure or part that is enclosed within its own membrane inside a cell and has a particular function. 
• how do organelles in photosynthetic bacteria maximise efficiency

  1. increasing the number photosynthetic protein complexes
  2. maximizing the size of the light-exposed membrane surface
  3. providing an idealized subcellular environment for photosynthesis
• what are plantomycetes

  true bacteria that show compartmentalisation, The DNA and ribosomes are surrounded by a biomembrane
• why are gram-negative planctomycetes unique

  • No peptidoglucanin cell wall (instead a protein coat)
  • An endocytosis-like mechanism for uptake of macromolecules
  • Contain a specialised organelle, the "anammoxosome" (enabling anaerobic oxidation of ammonium, thus a bacterial analogue of a mitochondrion?)
• what are magnetotactic bacteria

  gram-negative bacteria that detect earth's magnetic field
• why are some bacteria magnetotactic

  enables them to reach sediments of high oxygen, favourable for growth
• what are magnetosomes

  crystals of iron minerals that are magnetic
• formation of magnetosomes

  1. Invagination of cytoplasmic membrane
  2. Accumulation of ferrous irons (Fe2+):
  3. Nucleation of magnetosome formation
• what is MamKis

  an actin-like protein that forms filaments
• MreB similarity with actin

  <15%
• ParM similarity with actin

  <12%, 11% with MreB
• prokaryotic actin-like proteins functions

  • Organelle assembly and positioning
  • Plasmid Segregation
  • Cellular centering of nucleoid
  • Plasmid Segregation
  • Cell Shape
• how are ParM filaments dynamic

  • Polymerization of ATP-bound ParM at both ends
  • ATP-hydrolysis occurs spontaneously
  • Instable filament when ParM-ADP is at an end
• how do ParM filaments segregate plasmids

  • ParR binds the centromeric DNA-sequence (=ParC)
  • ParM polymerizes and binds to ParR
  • Filament elongation separates the plasmids
• what is FtsZ

  A prokaryotic protein that shares only 10-18% sequence identity with tubulin, despite sharing a similar fold
• common features of FtsZ

  • GTPase activity that controls polymerisation
  • Formation of protofilaments
  • Similar fold
• features of bacterial flagella

  • Flagella have a diameter of 20 nm and a length of 5-10 µm
  • Flagella are protein assemblies consisting of a single protein (flagellin)
  • Flagellin molecules moves through the hollow flagellum and bind to the tip of the polymer
  • The flagellum rotates and propells the cell
• monotrichious bacteria

  one flagellum at the pole of the cell
• peritrichious bacteria

  multiple flagella along a rod-shaped cell
• what is the "run-reverse-flick motility" of monotrichious bacterium

  • run= persistent motility in one direction
  • reverse= reorientation of 180°
  • flick= reorientation of ~90°
• what is rotation of flagella driven by

  by a basal "motor" that uses a proton gradient to rotate the flagellum