pathogen

Page 1: Pathogens

Page 2: Learning Outcomes

• List the main characteristics of viruses, bacteria, and fungi.

• Compare the structure of bacteria, viruses, and fungi.

• Explain the terms "lytic" and "latency."

Page 3: What is a Pathogen?

• Pathogens: Microorganisms that cause diseases.

  • Examples of Pathogens:

    • Viruses:

      • Influenza (Influenza virus)

      • Measles (Measles morbillivirus)

    • Bacteria:

      • Cholera (Vibrio cholerae)

      • Tuberculosis (Mycobacterium tuberculosis)

    • Protists:

      • Malaria (Plasmodium)

    • Fungi:

      • Ringworm (Trichophyton)

Page 4: Structure of Bacteria

• Major Structures in Bacteria:

  • Cytoplasm

  • Capsule

  • Flagella

  • Food granule

  • Plasmid

  • Nucleoid

  • Mesosome

  • Ribosomes

Page 5: Universal Features of Bacteria

• All bacteria possess:

  • Cell Wall: Made of peptidoglycan.

  • Cell Surface Membrane: Phospholipid bilayer with embedded proteins.

  • Nucleoid: Single circular strand of DNA, the bacterium's genetic material.

  • Ribosomes: 70S ribosomes, sites for protein synthesis.

Page 6: Additional Structures in Some Bacteria

• Some bacteria have additional structures:

  • Pili: Thread-like projections on the surface.

  • Flagella: Long, whip-like structures for movement.

  • Capsule/Slime Layer: Thick, slippery substance surrounding the cell wall.

  • Mesosomes: Internal extensions folded into the cytoplasm, may be involved in cellular respiration.

  • Plasmid: Small circles of extra DNA that code for specific characteristics.

Page 7: Viruses

• Characteristics of Viruses:

  • Smallest microorganisms (0.02-0.3µm).

  • Not considered cells; consist of genetic material and protein that invade living cells.

Page 8: Key Features of Viruses

• All viruses have:

  • Protein Coat (Capsid): Made of capsomeres.

  • Nucleic Acid: Genetic material, either DNA or RNA.

  • Virus Attachment Particles (VAPs): Specific proteins targeting host cell proteins.

  • Some possess a Lipid Envelope derived from the host cell membrane.

Page 9: Types of Viruses

• Bacteriophage: Infects bacteria.

• Influenza: Viral infection.

• Virus Structure:

  • Protein coat

  • Nucleic acid: either DNA or RNA.

  • Envelope Structures:

    • DNA virus

    • RNA virus

    • Retrovirus (uses reverse transcriptase)

Page 10: Viral Reproduction

• Once inside a host cell, viruses can follow one of two pathways:

  • Lysogenic Pathway

  • Lytic Pathway

Page 11: Lysogenic Pathway (Latency)

• The viral DNA replicates using the host cell's DNA.

• Virus enters a latent state without producing new viruses, residing in the body without active replication.

Page 12: Lytic Pathway

• Viral genetic material may replicate independently right after entering the host.

• Mature viruses are created, leading to the bursting of the host cell and release of new virus particles.

Page 13: Fungi

• Fungi are eukaryotic organisms, including microorganisms like yeasts, molds, and mushrooms.

• Classified under the kingdom fungi.

Page 14: Structure of Fungi

• Most fungi have filamentous structures, apart from yeast cells.

• Can be unicellular or multicellular.

• Composed of hyphae (long thread-like structures) forming a mesh-like structure called mycelium.

Page 15: Fungi as Pathogens

• Pathogenic fungi significantly affect human health, causing infections such as athlete's foot and ringworm.

Page 16: Comparison of Bacteria, Fungi, and Viruses