bacteria

• Bacteria are metabolically active single-celled prokaryotic organisms that divide by binary fission
• The longest bacterium rods are 7 μm in size, similar to yeasts and human red blood cells
• Bacteria come in three basic shapes: spherical (cocci), rod-shaped (bacilli), and spiral-shaped (spirilli)
• Some bacteria can endure extreme temperatures and pressures
• Affective Objective

  • Collaborate effectively with peers in sharing observations, discussing results, and contributing to a collaborative understanding of bacterial morphology and growth requirements
• Mycoplasma, the smallest microbe, is comparable in size to poxviruses and may survive without a host
• Bacteria reproduction occurs by binary fission where one cell splits in half to become two daughter cells
• Bacterial morphology can be easily viewed with a compound light microscope
• Club-shaped Rod Bacteria are thinner on one side than the other, for example, Corynebacterium
• Pleomorphic Bacteria do not have a defined form and can alter shape
• Spirilla

  • More rigid than spirochetes
  • Have a similar structure with spirochete but lack the endoflagella
• Morphologic arrangements of bacteria


  • Diplococci
  • Streptococci
  • Staphylococci
  • Tetrad
  • Sarcina / Octad
  • Coccobacilli
  • Diplobacilli
  • Streptobacilli
  • Palisade
  • Vibrio
  • Spirochetes
  • Spirilla
• Filamentous Bacteria are long, thin, and sometimes divide to form branches resembling strands of hair or spaghetti called mycelium
• Spirochetes

  • Flexible & have an axial filament which helps in motility
  • Filaments travel the length of the bacterium, aiding in the twisting of the bacteria’s motility
• Box-shaped/Rectangular Bacteria include Haloarcula marismortui; Triangular-shaped Bacteria include Haloarcula; Stalked Bacteria possess a stalk on one end of the cell, for example, Caulobacter crescentus; Star-shaped Bacteria include Stella humosa
• Appendaged Bacteria produce distinct structures such as pillus or fimbriae, making them more virulent
• Haloarcula


  • saline environments such as salt lakes, marine salterns, and saline soils
• Propionibacterium acnes, the reason for acne, is a bacillus
• Caulobacter crescentus


  • found in lakes and streams
• General shape of bacteria is diverse
• The bacteria that causes leptospirosis has a spiral shape
• Envelope Structures

  • Glycocalyx
  • Capsule
  • Slime layer
  • Cell Wall
• N. gonorrhoeae is also known as gonococcus
• Capsule


  An outer, viscous covering on some bacteria composed of a polysaccharide or polypeptide. Function: Protects against phagocytosis
• Teichoic acids

  A polysaccharide found in gram-positive cell walls
• The movement of a bacterium toward or away from a particular stimulus is called taxis
• Cell Wall


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


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

  Present in gram-negative cell walls, located outside of the peptidoglycan layers
• Classification of Bacteria As To Gram-Staining are gram-positive or gram-negative
• Campylobacter coli has a helical form
• Streptococcus pyogenesis, the cause of strep throat, is round
• 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
• Stalked Bacteria


  • Possess a stalk on one end of the cell
• Star-shaped Bacteria


  • Stella humosa found in freshwater, soil, and sewage
• Some structures play specific roles in bacterial virulence, bacterial identification, and targets of antimicrobial agents
• Mycobacterium Tuberculosis is an acid-fast bacillus and is rod-shaped
• Slime layer

  A glycocalyx that is unorganized and loosely attached to the cell wall. Function: Mediates adherence to surfaces
• Streptococcus pneumoniae is round
• Glycocalyx

  A gelatinous polymer surrounding a cell located outside their cell wall