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Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
Bacterial Physiology and genetics
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Bacterial Physiology and genetics

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prepared by suzan qarani

prepared by suzan qarani

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  • 1.
    • Bacterial Physiology and Genetics
  • 2.
    • Understand the meaning of the growth.
    • Important factors for growth.
    • How genetic variation occur in bacteria?
  • 3.
    • Meaning of Bacterial physiology ?
    • The biochemical reactions that together enable bacteria to live, grow and reproduce.
  • 4. Microbial Growth
  • 5. Microbial Growth - refers to the number of cells
    • Requirements for Growth
      • Physical
      • Chemical
  • 6. Nutritional Requirements Physical Requirements Autotrophs Heterotrophs Organic and Inorganic substances
  • 7. Physical Requirements
    • Temperature
      • psychrophiles (cold loving microbes )
        • range 0 0 C - 20 0 C
      • mesophiles (moderate temp. loving microbes)
        • range 25 0 C - 40 0 C
      • thermophiles (heat loving microbes)
        • range 55 0 C - 88 0 C
  • 8. pH
    • Most bacteria grow between pH 7.2 - pH 7.4
    • Very few can grow at below pH 5
      • many foods, like cheeses are preserved from spoilage by acids produced during fermentation
  • 9. Oxygen
    • Bacteria can be classified base on their oxygen requirements
  • 10. 1. Obligate Aerobes
  • 11. 2. Obligate Anaerobes
  • 12. 3. Facultative Aerobes Facultative Anaerobes
  • 13. 4. Microaerophilic
  • 14. Oxygen is lethal to some organisms
    • All organisms produce superoxide ( O 2 -)
    • Superoxide is toxic to cells
    • Superoxide must be neutralized
  • 15. Superoxide dismutase
    • O 2 - + O 2 - + 2 H + -------> H 2 O 2 + O 2
    • Hydrogen peroxide is also toxic to cells and it must be neutralized
  • 16. Catalase
    • 2 H 2 O 2 --------> 2 H 2 O + O 2
    • Obligate Anaerobes lack:
      • Superoxide dismutase ( SOD )
      • Catalase
  • 17. Phases of Growth
    • 4 Phases
    • 1. Lag Phase
    • 2. Log Phase
    • 3. Stationary Phase
    • 4. Death Phase
  • 18. 1. Lag Phase
    • Bacteria are first introduced into an environment or media
    • Bacteria are “checking out” their surroundings
    • cells are very active metabolically
    • # of cells changes very little
  • 19. 2. Log Phase
    • Rapid cell growth (exponential growth)
    • population doubles every generation
    • microbes are sensitive to adverse conditions
      • antibiotics
  • 20. 3. Stationary Phase
    • Death rate = rate of reproduction
    • cells begin to encounter environmental stress
      • lack of nutrients
      • lack of water
      • not enough space
      • metabolic wastes
      • oxygen
      • pH
    Endospores would form now
  • 21. 4. Death Phase
    • Death rate > rate of reproduction
    • Due to limiting factors in the environment
  • 22. Bacterial Growth - increase in the # of cells
    • Binary Fission
    • Generation Time (Doubling Time)
      • time required for a cell to divide
      • most about 1 Hr. To 3 Hrs.
        • E. coli - 20 minutes
        • Mycobacterium tuberculosis - 24 Hrs.
  • 23. Binary Fission - unchecked
    • E. coli - generation time of 20 min.
    • 20 generations (about 7 hrs.)
      • 1 million cells
    • 30 generations ( about 10 hrs.)
      • 1 billion cells
    • 72 generations ( about 24 hrs.)
      • 1 x 10 21
        • 1,000,000,000,000,000,000,000 cells
  • 24. Limiting factors in the environment
    • Lack of food, water or nutrients
    • space
    • accumulation of metabolic wastes
    • lack of oxygen
    • changes in pH
    • temperature
  • 25. Bacterial Genetics
    • Genetics is the study of heredity and variation.
    • Bacterial genetics is used as a model to understand DNA replication, genetic characters, their changes & transfer to next generations.
  • 26. Double helical structure of DNA Replication
  • 27. Important enzymes involved in Replication:
    • DNA-dependent DNA polymerase.
    • if Error: nuclease enzyme
    • Restriction enzymes
  • 28. Genetic Information In Bacteria Carries properties like virulence, pathogenicity & resistance Extrachromosomal genetic material in the cytoplasm Replicate independently Virus infecting bacteria Chromosome Plasmid Bacteriophage
  • 29. PLASMIDS
    • Circular DNA molecules
    • Important vectors in genetic engineering
    • EPISOME
      • Plasmid DNA integrated with chromosomal DNA.
      • …………………………………………………… .
      • Transmissible and non-transmissible Plasmids
  • 30. Mechanisms Of Genetic Variations
    • Mutation
    • Transfer or exchange of genetic material
      • Transformation
      • Transduction
      • Conjugation
      • Transposition
  • 31. 1. Base substitution
    • Results of mutation -
      • Missense mutation – triplet code is altered so that a different amino acid is present at a particular position in the protein.
      • Nonsense mutation – converts a codon that specifies an amino acid into a termination codon.   
  • 32. 2. Frame Shift Mutation
    • Cause - Deletion or insertion of a base - changes all of the codons downstream from the change
  • 33. 3- Insertion
    • Additional pieces of DNA
  • 34. Gene Transfer in bacteria:
    • Conjugation.
    • Transduction.
    • Transformation.
    • Transposition.
  • 35. Process of Conjugation
  • 36. Process of Transduction
  • 37.  
  • 38. Process of Transformation
  • 39. 4- Tranposition.
    • By Transposone
  • 40.
    • Thank you

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