Bacteria (example of monera)

Bacteria (example of monera)

1. What are they: They are unicellular organisms, prokaryotes (no membrane bound nucleus/ organelle)

   • They're classified according to 3 shapes: Spherical, Rod and Spiral. These are all bacterial cells
     • Spiral: (spirrillum) e.g treponema pallidum (syphillis)
     • Spherical: (cocci) e.g staphylococcus aureus (pneumonia and throat infection)
     • Rod: (bacillus) e.g bacillus anthracis (anthrax)
   • • Always present: cell wall, cell membrane, cytoplasm, ribosome, loop of DNA
       • cell wall: protects cell, supports and strengthens cell
       • cell membrane: retains cell contents and controls what passes in and out of the cell
       • cytoplasm: fluid that contains cell organelles
       • ribosome: makes protein
       • Loop of DNA: contains genes that control the cell
     • Sometimes present: flagella, capsule(dry or slime layer(moist) and plasmid
       • flagella: allows cell to move/swim
       • capsule/slime layer: prevents water loss
       • plasmid: contains genes

2. Reproduction

   • is asexual
     • method is known as binary fission
   • 1) DNA replicates and move to each end of the cell (they elongate)
     • 2) Cell membrane and cell wall pinch in to form two separate cells
       • 3) Each contains its own loop of DNA, they are known as daughter cells

3. Endospores

   • is a tough resistant cell that forms around one of the loops of DNA inside the existing cells
   • Can survive unfavourable conditions

4. Conditions for bacterial growth

   • Nutrition, Temperature, Oxygen, concentration, pH, External solute concentration, Pressure

5. Growth curve:

   • A)Lag phase B)Log phase C)Stationary phase D)Decline phase E)Survival phase
     • Lag phase- does not change as it's reacting to the new environment
     • Log phase- increases rapidly to reproduce at the maximum rate
     • Stationary phase- does not change as the bacteria may be short for food, water, space or oxygen
     • Decline phase- falls rapidly because the death rate is greater than the reproduction rate
     • Survival phase- small number of bacteria remain dormant as spores

6. Food processing

   • Batch Food Processing and Continuous-Flow Food Processing

7. Beneficial and Harmful bacteria

   • Beneficial: to make yoghurt and cheese, genetically engineered bacteria make enzymes and hormones
   • Harmful: causes food to decay and pathogenic bacteria cause diseases such as pneumonia and tetanus

8. Antibiotics

   • they are chemicals produced but micro organisms that kill or prevent the growth of bacteria without damaging the human tissue
     • Antibiotic resistance
       • When an antibiotic is first used it kills the bacteria in the organism. Soon the mutation in one bacterium will cause that bacterium to be resistant to the antibiotic
         • As all the antibiotic-sensitive bacteria are killed off, the resistant bacterium has no competition and can form huge numbers of resistant bacteria
           • Bacteria have developed and resistance to most known antibiotics. They are called multi-resistant bacteria
             • The over-use of antibiotics has accelerated the evolution of the multi-resistant bacteria
     • Antibiotics don't kill viruses.
       • Examples: penicillin and streptomycin

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