Structure and Classification of Bacteria

• Bacteria belong to the kingdom monera.
• All members of this kingdom are prokaryotes.
• Bacteria are single celled living organisms found in all parts of the biosphere.

Structure of Bacteria

• Genetic material
  • Bacteria do not contain a nucleus (prokaryotic).
  • Bacteria contain both DNA and RNA.
  • DNA: Found loose in the cytoplasm.
  • RNA: Found in the ribosome.
  • Many bacteria also have a plasmid.
  • A plasmid is a circular loop of DNA that contains genes that benefit the bacteria, such as those for antibiotic resistance.
• Bacterial cells do not contain mitochondria or chloroplasts.
  • Respiration takes place in the cytoplasm.
• Cell wall: provides structure and protection.
• Some bacteria have a capsule or slime layer.
  • Surrounds the cell wall to prevent the bacterial cell from drying out.
  • Particularly bacteria in dry environments.
• Some bacteria have a flagellum.
  • A tail like structure for movement.
  • Particularly bacteria in wet environments.

Classification of Bacteria

Bacteria are classified by shape.

1. Rod-shaped e.g. tetanus, TB, typhoid
2. Round e.g. food poisoning, pneumonia, sore throat
3. Spiral e.g. syphilis, cholera