CHAPTER 3.

• What determines the shape of a bacterium?

  Heredity
• What does monomorphic mean in relation to bacteria?


  Bacteria maintain a single shape
• What does pleomorphic mean?


  Variation in the form of bacteria
• What are the different shapes of cocci bacteria?

  • Coccus (cocci): spherical
  • Diplococci: remain attached in pairs
  • Streptococci: form chainlike patterns
  • Tetrads: groups of four
  • Sarcinae: cubelike groups of eight
  • Staphylococci: grape-like clusters
• What are the different shapes of bacilli bacteria?

  • Bacillus (bacilli): rod-like
  • Diplobacilli: appear in pairs
  • Streptobacilli: appear in chains
  • Coccobacilli: oval, resembling cocci
  • Vibrios: curved rods
  • Spirilla: helical shape
  • Spirochetes: corkscrew-shaped
• What is the glycocalyx in bacteria?


  It is a polymeric substance that surrounds bacterial cells
• What does the term glycocalyx literally mean?


  Sugar coat
• What is the difference between a capsule and a slime layer in glycocalyx?


  A capsule is organized and firmly attached, while a slime layer is unorganized and loosely attached
• What is motility in bacteria?


  The ability of an organism to move by itself
• What are flagella in bacteria?


  Long filamentous appendages that propel the bacteria
• What are the three basic parts of a flagellum?


  1. Filament: long helical structure made of flagellin
  2. Hook: connects filament to the basal body
  3. Basal Body: motor structure embedded in the cell membrane
• What does the term "monotrichous" refer to in bacteria?


  Bacteria with a single polar flagellum
• What does "amphitrichous" mean?


  Bacteria with two flagella, one at each end
• What does "lophotrichous" indicate?


  Bacteria with two or more flagella at one or both ends
• What does "peritrichous" mean?


  Bacteria with flagella all over their surface
• What does "atrichous" refer to?


  Bacteria without flagella
• What is a "run" in bacterial movement?


  Movement in one direction for a length of time
• What causes "tumbles" in bacterial movement?


  Periodic, abrupt changes in direction due to reversal of flagellar rotation
• What is a fimbria?


  An appendage on a bacterial cell used for attachment
• What is a sex pilus?


  An appendage used for the transfer of genetic material during conjugation
• What are the functions of the bacterial cell wall?


  • Maintains the characteristic shape of the cell
  • Prevents the cell from bursting when fluids flow into it
• What is the difference between Gram-negative and Gram-positive bacteria?

  Gram-negative have a prominent periplasmic space and outer membrane, while Gram-positive have thicker peptidoglycan and thicker cell wall
• What is peptidoglycan?


  The single most important component of the bacterial cell wall
• What is the structure of peptidoglycan?


  It consists of a glycan backbone with peptide side chains
• What is teichoic acid?


  A component present in the cell wall of Gram-positive bacteria
• What is the function of teichoic acid?


  It furnishes attachment sites for bacteriophages and directs autolytic enzymes
• What is lipoteichoic acid associated with?


  Primarily associated with the cell membrane
• What is the significance of the Gram-negative envelope?


  It binds the outer membrane to the cell wall
• What is lipopolysaccharide also known as?


  Endotoxin
• What are the three regions of lipopolysaccharide?


  Outer O antigen, middle core, inner lipid A region
• What is responsible for the toxic properties of lipopolysaccharides?


  Lipid A
• What is the cytoplasm composed of?


  About 80% water, nucleic acids, proteins, carbohydrates, lipids, inorganic ions, and low molecular weight compounds
• What does the nucleoid contain?


  A single, long, circular molecule of DNA
• What are plasmids?


  Extrachromosomal genetic elements that can replicate autonomously
• What is the significance of ribosomes in bacteria?


  They are involved in protein synthesis and are abundant in the cytoplasm
• What is the size of prokaryotic ribosomes?


  70S
• What is the size of eukaryotic ribosomes?


  80S
• What are the types of inclusions found in prokaryotic cells?

  • Metachromatic granules: stain red with certain dyes
  • Polysaccharide granules: consist of glycogen and starch
  • Lipid inclusions: revealed by fat-soluble dyes
• What color do glycogen granules appear when iodine is applied?


  Reddish brown
• What color do starch granules appear when iodine is applied?


  Blue