Bacterial Anatomy and Physiology

• What type of organisms are bacteria?

  Prokaryotes
• What is the protoplast of a bacterial cell?

  The part bound by the cytoplasmic membrane
• What is the structure closely covering the cytoplasmic membrane?

  Cell wall
• What is the cytoplasm in bacterial cells?

  Aqueous environment packed with ribosomes and other complexes
• What are the basic shapes of bacterial cells?

  • Spherical (coccus)
  • Rod-shaped (bacillus)
  • Comma-shaped (vibrio)
  • Spiral (spirillum and spirochaetes)
  • Filamentous
• What type of DNA do bacteria have?

  Single, circular double-stranded DNA
• What is the state of bacterial DNA?

  Exists in a supercoiled state
• What are plasmids in bacteria?

  Extra-chromosomal DNA
• What is the size range of bacterial ribosomes?

  10-20 nm
• What is the sedimentation coefficient of bacterial ribosomes?

  70S (30S and 50S)
• What is the function of ribosomes in bacteria?

  Protein synthesis
• What forms when multiple ribosomes attach to a single mRNA molecule?

  Polysomes
• What is the thickness of the cytoplasmic membrane in bacteria?

  1. 10 nm thick
• What are the main components of the cytoplasmic membrane?

  Mainly phospholipids and proteins
• What are the functions of the cytoplasmic membrane?

  Permeability barrier

  transport of solutes

  energy generation

  location of numerous enzyme systems
• What does the cell wall encase?

  The protoplast
• What is the characteristic of the bacterial cell wall?

  Strong, relatively rigid, and elastic
• What size solute molecules can pass through the bacterial cell wall?

  Freely permeable to solutes <10 kDa
• Why is the integrity of the cell wall important?

  Cell survival depends on it
• What is lysis in bacteria?

  Lethal disintegration and dissolution
• What is the main strengthening component of the bacterial cell wall?

  Peptidoglycan (PG)
• How does the peptidoglycan layer differ in Gram-positive and Gram-negative bacteria?

  Gram-positive has a thick PG layer while Gram-negative have a thin PG layer
• What are the components of peptidoglycan?

  1. N-acetylglucosamine (NAG) and N-acetylmuramic (NAM) acid
• How are NAG and NAM connected in the bacterial cell wall?

  By interpeptide bridges
• What do NAM units carry in the bacterial cell wall?

  A short peptide
• What are the amino acids found in the short peptide of NAM?

  1. L-alanine,
  2. D-glutamic acid,
  3. Meso-diaminopimelic acid (Gram-negative) or L-lysine (Gram-positive)
  4. D-alanyl-D-alanine
• What acids do Gram-positive bacteria contain?

  Teichoic and lipoteichoic acids
• What does the outer membrane of Gram-negative bacteria contain?

  Lipopolysaccharide (LPS)
• What are the functions of lipopolysaccharide (LPS)?

  Contains porins and adhesins

  Protects PG from the effects of lysozyme

  Inhibits the entry of many antibiotics
• What is Lipid A in relation to LPS?

  Forms endotoxin
• What can endotoxin cause when released into the bloodstream?

  Endotoxic shock
• What is the role of mycolic acids in Mycobacteria?

  Forms an extremely hydrophobic external layer
• What is the function of the capsule in bacteria?

  Evade host defenses and adhere to surfaces
• What is a virulence factor in bacteria?

  Antiphagocytic properties
• What is the unique structure of Mycobacteria's cell wall?

  PG is Intertwined with arabinogalactan polymer and surrounded by mycolic acid, cord factor, wax D, and sulfolipids
• What is the staining characteristic of Mycobacteria?

  Described as staining acid-fast
• What do Corynebacterium and Nocardia produce?

  Mycolic acid lipids
• What do Mycoplasmas lack?

  No peptidoglycan cell wall
• What do Mycoplasmas incorporate into their membranes?

  Steroids from the host
• What are flagella in bacteria?

  Organs of locomotion