Bacterial Culture and Growth

• Bacteria are (prokaryotes/eukaryotes): prokaryotes
• The structure of bacteria is less complex due to the lack of:

  • nucleus
  • membrane-bound organelles
  • mitochondria
  • endoplasmic reticulum
  • Golgi complexes
• Capsule

  • acts as a shield against phagocytosis and helps adhesion
• Bacteria without a capsule are (more or less) less virulent.
• Bacterial cell walls consist of peptidoglycan.
• Gram-positive bacteria has a thick layer of peptidoglycan.
• Gram-negative bacteria has a thin layer of peptidoglycan.
• Staining dye is retained more by gram-positive bacteria.
• Cell wall

  • helps maintain bacterial shape
• Plasma membrane

  • encloses cytoplasm
• Cytoplasm

  • gel-like substances that are composed of water, cell components, enzymes, and organic molecules
• Plasma membrane

  • selectively permeable membrane
• Ribosomes

  • sites of protein synthesis
  • can be spread all over the cytoplasm or attached to the plasma membrane
• Nucleoid

  • irregularly shaped region that contains the cell's chromosomes or genetic material
• Describe bacterial chromosomes

  mostly single circle of double stranded DNA but some have linear and have more than 1; contain genes needed for protein synthesis
• Plasmids

  • small ds-DNA that are independent of the chromosome
  • can be circular or linear
• Plasmids

  • have relatively few genes and genetic information is non-essential to the bacterium
• Plasmids

  • can confer a selective advantage to the bacteria (increase resistance to antibiotics)
• Pili

  • hair-like structures that allow them to attach to other cells
• Fimbriae

  • smaller, shorter pili
• Flagella

  • long, whip-like protrusions that allow movement of bacteria
• Nucleolus

  • looks extra dark/dense in a micrograph
  • where ribosomal RNA is being produced
• [Eukaryotic or prokaryotic]

  Has membrane-bound nucleus: eukaryotic
• [Eukaryotic or prokaryotic]

  Has other membrane-bound organelles such as mitochondria and golgi apparatus: eukaryotic
• [Eukaryotic or prokaryotic]

  DNA is in multiple strands: eukaryotic
• [Eukaryotic or prokaryotic]

  larger in size: eukaryotic
• [Eukaryotic or prokaryotic]

  no membrane-bound nucleus: prokaryotic
• [Eukaryotic or prokaryotic]

  no membrane-bound organelles: prokaryotic
• [Eukaryotic or prokaryotic]

  DNA is circular: prokaryotic
• [Eukaryotic or prokaryotic]

  smaller in size: prokaryotic
• [Eukaryotic or prokaryotic]

  Fungi: eukaryotic
• [Eukaryotic or prokaryotic]

  Protists: eukaryotic
• [Eukaryotic or prokaryotic]

  Bacteria: prokaryotic
• [Eukaryotic or prokaryotic]

  Archaea: prokaryotic
• S-layer

  • tight layer of mosaic cells made of many identical proteins
  • rigid coat
  • variably demonstrated ordered protein layer
  • functions: molecular sieve, protection, adherence, immune evation
• Capsule

  • also known as slime layer
• Capsule

  • sticky outermost layer made of polysaccharides
  • functions: adherence, prevents cell from drying out, evasion of immune system
• Capsule

  • help deter phagocytosis as they are slippery and protect against degradation of phagolysosomes of macrophages and neutrophils
• Cell wall

  • bacterial structure consisting of polysaccharide glycan chains with tetrapeptide or longer side-chains that are cross-liked through peptide bonds
• Lipopolysaccharides are present in all gram- negative bacteria.