Microbial Cell Structure and FUnction

• Morphology deals with the size, shape, and arrangement of a living organism
• Cellular morphology is the study of the size and shape of the cell
• A typical bacteria is <3 um in size

  • Cocci: 0.5 to 3 um in diameter
  • Bacilli: 0.15 to 2 um in width and 0.5 to 20 um in length
• Coccus - spherical and ovoid
• Bacillus - cylindrical
• Spiral - curve or loose spiral
• Bacterial shapes

  A) cocci

  B) bacilli

  C) spirochetes

  
• Bacterial Arrangement

  A) singly

  B) strepto

  C) staphylo

  D) diplo

  E) sarcinae

  F) spirochetes

  G) pleomorphic

  
• Prokaryotic Cell - Exhibited by organisms falling under Domain Bacteria and Domain Archaea
• What is this?

  Answer: Cell membrane

  
• What is this?

  Answer: Bacterial membrane

  
• bacterial membrane is composed of hydrophobic tails and hydrophilic head
• Hydrophobic tails - fatty acids (inward)
• Hydrophilic heads - glycerol molecule containing phosphate (outward)
• Hopanoids - Strengthened by sterol-like molecules present in bacteria; Sterols strengthen the membranes of eukaryotic cells where there is an absence of cell wall
• Cell Wall - layer outside the cytoplasmic membrane
• What is this?

  A) the cell wall

  
• Lysozyme - weakens the peptidoglycan and causes cell lysis
• Lysozyme - act as a major line of defense against bacterial infection which are present in human secretions including tears, saliva, and other bodily fluids
• lysozyme - destroys pre-existing peptidoglycan, penicillin blocks a key step in its biosynthesis
• Peptidoglycan - made up of rigid polysaccharide
• What is this?

  Answer: peptidoglycan

  
• Identify

  A) teichoic acid

  B) lipoteichoic acid

  C) lps or lipopolysaccharide

  D) outer membrane

  
• outer membrane - found in the second lipid bilayer
• Periplasm - The space located between the outer surface of the cytoplasmic membrane and the inner surface of the outer membrane
• Periplasm - spans about 15 nm
• Porins - Channels for the entrance and exit of solutes
• Two types of porins:

  1. non-specific porins
  2. specific porins
• Pseudomurein = peptidoglycan
• S-layer - paracrystalline surface layer
• S-layer - It is the most common type of cell wall in archaea
• S-layer - consists of interlocking molecules of protein or glycoprotein and retains periplasmic proteins and prevents their drifting away in gram-negative Bacteria
• identify

  A) glycocalyx

  B) capsule

  C) slime

  D) fimbriae

  E) pili

  F) hami

  
• Capsule - is an organized in a tight matrix that excludes small particles and is tightly attached. Readily visible by light microscopy
• Identify

  A) glycocalyx

  
• Fimbriae - Thin filamentous structures made of protein that extend from the surface of a cell
• Pili - Typically longer and only one or a few of it are present on the surface of a cell
• Identify

  A) hamus or hami

  
• Gas Vesicles - Colonical-shaped structures made of protein
• Gas vesicles -Appears as irregular bright inclusions seen in light microscopy or transmission electron microscope