Week 2

• Spirochetes


  • Flexible & have an axial filament which aids in motility
  • Filaments travel the length of the bacterium, aiding in twisting motility
• Box-shaped/Rectangular Bacteria examples: Haloarcula marismortui, Triangular-shaped Bacteria examples: Haloarcula, Stalked Bacteria example: Caulobacter crescentus, Star-shaped Bacteria example: Stella humosa
• The time it takes for one bacterial cell to split into two cells is referred to as that organism’s generation time
• Filamentous Bacteria are long, thin, and sometimes divide to form branches resembling strands of hair or mycelium
• Appendaged Bacteria


  • Produce distinct structures like pillus or fimbriae
  • Those producing appendages are more virulent
• Bacteria shapes

  • Spherical (cocci)
  • Rod-shaped (bacilli)
  • Spiral-shaped (spirilli)
• Capsule

  An outer, viscous covering on some bacteria composed of a polysaccharide
• Bacteria reproduction is by binary fission where one cell splits in half to become two daughter cells
• Morphologic arrangements after binary fission

  • Diplococci
  • Streptococci
  • Staphylococci
  • Tetrad
  • Sarcina / Octad
  • Coccobacilli
  • Diplobacilli
  • Streptobacilli
  • Palisade
  • Vibrio
  • Spirochetes
  • Spirilla
• Spirilla


  • Helical-shaped/Corkscrew form
  • More rigid than spirochetes
  • Have a flagellum but lack endoflagella
• Pleomorphic Bacteria do not have a defined form and can alter shape
• Glycocalyx

  A gelatinous polymer surrounding a cell located outside the cell wall
• Club-shaped Rod Bacteria are thinner on one side than the other
• Bacteria with stalk on one end of the cell

  • Caulobacter crescentus (found in lakes and streams)
  • Star-shaped Bacteria Stella humosa (found in freshwater, soil, and sewage)
• Cell Wall

  The outermost component of all bacteria except Mycoplasma species, which are bounded by a cell membrane, not a cell wall
• Capsule


  An outer, viscous covering on some bacteria composed of a polysaccharide or polypeptide. Function: Protects against phagocytosis, highly organized and firmly attached to the cell wall
• Both gram positive and gram negative cell walls contain peptidoglycan (also known as murein)
• Types of Flagella arrangement

  • Monotrichous (a single flagellum)
  • Lophotrichous (a tuft of flagella coming from one pole)
  • Amphitrichous (flagella at both poles of the cell)
  • Peritrichous (flagella distributed over the entire cell)
  • Atrichous (Bacteria that lack flagella)
• Flagella

  A thin appendage from the cytoplasm to the cell exterior. Composed of basal body, hook, and filament
• Polysaccharides

  • Carbohydrate consisting of many sugar units; glycogen, cellulose, and starch are examples
• Periplasmic space

  The space between the plasma membrane and outer membrane of Gram-negative cell wall
• Cytoplasmic Membrane

  Also called Cell membrane or plasma membrane; Functions: Selective permeability
• Pilin


  Common Pili involved in conjugation - the transfer of genetic material from one cell to another
• Murein Sacculus


  Peptidoglycan, a polymer made up of sugars and amino acids that forms a mesh-like peptidoglycan layer outside of most bacteria's plasma membrane, creating the cell wall. Function: provide rigidity, strength, and protection
• Glycocalyx

  A gelatinous polymer surrounding a cell located outside their cell wall
• The movement of a bacterium toward or away from a particular stimulus is called taxis
• Gram-negative cell wall has an outer membrane and lipoprotein with lipopolysaccharide (LPS) components
• Teichoic acids

  A polysaccharide found in gram-positive cell walls
• Cytoplasm

  In a prokaryotic cell, everything inside the plasma membrane
• Slime layer

  A glycocalyx that is unorganized and loosely attached to the cell wall. Function: Mediates adherence to surfaces
• Acid-Fast bacteria have a lipid-rich outer layer and peptidoglycan inner layer
• Pili or Fimbriae


  Appendages on bacterial cells used for attachment and conjugation & gliding motility
• Axial Filaments


  The structure for motility found in spirochetes; also called endoflagellum
• Ribosomes


  Tiny spherical organelles that make proteins by joining amino acids together; Bacterial ribosomes are composed of two subunits with densities of 50S and 30S; All prokaryotes have 70S ribosomes; Function: for protein synthesis whereby they receive and translate genetic instructions for the formation of specific proteins
• Endospores


  A resting structure formed inside some bacteria; Dipicolinic acid (DPA) forms complex with calcium ions within endospore core, plays role in endospore heat resistance & in protecting endospore genome from UV light; Function: allows the bacterium to produce a dormant and highly resistant cell to preserve the cell's genetic material in times of extreme stress; Endospores can survive environmental assaults that would normally kill the bacterium
• Nucleoid


  The region in a bacterial cell containing the chromosome
• Endotoxins are generated during the breakdown of bacterial cell wall when bacteria die; They activate host complement and coagulation cascades, causing septic shock; Non-disease-specific symptoms include Fever, Pain, Shock, Fatigue, Discomfort
• Sporulation

  Process of spore and endospore formation; also called sporogenesis
• Mesosomes


  An extension of the cell membrane presence in cytoplasm as infolding; Function: serve in DNA replication and guide distribution of duplicated bacterial chromosomes into the two daughter cells during cell division; Carry enzymes for aerobic respiration and increase the surface area for the same
• Cell division


  The bacterial cell cycle can be arbitrarily divided into two segments: a DNA cycle that includes DNA replication and chromosome segregation; Bacterial binary fission is the process that bacteria use to carry out cell division