Pathogens and Disease Quiz

Pathogens and Disease

• Pathogens cause disease in plants and animals
• Bacteria: Examples include Tuberculosis (TB), Bacterial Meningitis, and ring rot
• Viruses: Examples include HIV/AIDS, Influenza, and Tobacco Mosaic Virus
• Protoctista: Examples include Malaria and potato/tomato late blight
• Fungi: Examples include Black Sigatoka, Ringworm, and Athlete's foot

Transmission Mechanisms

• Direct Transmission: Physical contact is required, like touching an infected individual.
• Indirect Transmission:
  • Vectors (e.g., mosquitoes, aphids) carry pathogens.
  • Spores (fungal) spread through the air or soil.
  • Environmental conditions (warm, damp) favor pathogen spread.
  • Social factors (crowded living) increase transmission risk

Plant Defenses

• Chemical Defenses: Produce antimicrobial chemicals and toxins.
• Physical Responses:
  • Callose deposition thickens cell walls at infection sites.
  • Lignin reinforces cell walls.
  • Stomatal closure prevents pathogen entry.

Animal Non-Specific Defenses

• Physical Barriers: Skin (sebum) and mucous membranes trap pathogens.
• Processes:
  • Blood clotting/wound repair (platelets).
  • Inflammation increases blood flow to the infection site.
  • Expulsive reflexes (coughing, sneezing).

Phagocytes and Their Action

• Structure: Neutrophils (multi-lobed nuclei) and macrophages engulf pathogens.
• Mode of Action:
  • Cytokines attract immune cells.
  • Opsonins coat pathogens to make them easier to engulf.
  • Phagosome and lysosome digest the pathogen.

B and T Lymphocytes and Function

• B Lymphocytes:
  • Plasma cells produce antibodies.
  • Memory cells provide long-term immunity.
• T Lymphocytes:
  • Helper T cells activate B cells and macrophages.
  • Killer T cells destroy infected cells.
  • Regulator T cells control immune response.

Immune Responses and Immunity

• Primary Response: First exposure, slower response; B and T cells are activated.
• Secondary Response: Faster and stronger due to memory cells.
• Active Immunity (natural/artificial): Body produces its own antibodies.
• Passive Immunity (natural/artificial): Antibodies are given.

Antibodies and Their Roles

• Structure: Y-shaped molecule with variable regions for antigen binding.
• Functions: Neutralization, agglutination, and opsonization.

Opsonins, Agglutinins, and Anti-Toxins

• Opsonins: Mark pathogens for phagocytosis.
• Agglutinins: Clump pathogens together.
• Anti-Toxins: Neutralize toxins.

Autoimmune Diseases

• Autoimmune diseases are conditions where the immune system attacks the body's own cells.
• Examples include arthritis and lupus.

Vaccination Principles

• Vaccinations introduce antigens to stimulate the immune response and create memory cells.
• Vaccination programs are adapted to changing pathogens.
• Global considerations include accessibility and herd immunity.

Antibiotic Sources and Risks

• Sources: Natural (e.g., penicillin) and modern approaches (synthetic biology, personalized medicines).
• Risks: Overuse leads to antibiotic resistance. Stewardship is crucial.