Overview
This lecture covers communicable diseases caused by different pathogens, how the body defends against infection, the use of vaccines and antibiotics, and the development of monoclonal antibodies.
Types of Pathogens
- Communicable diseases are caused by pathogens: viruses, bacteria, fungi, and protists (single-celled parasites).
- Viruses consist of a protein coat and genetic material and reproduce by injecting their code into host cells.
- Bacteria release toxins that damage body cells.
- Fungi cause infections like athlete's foot and plant diseases.
- Protists cause diseases like malaria by invading and destroying red blood cells.
Examples of Diseases
- Measles is a viral disease causing rash and is spread by droplets.
- HIV/AIDS is a viral STI that weakens the immune system; spread by sexual contact and sharing needles.
- Salmonella (from undercooked food) and gonorrhea (STD) are bacterial infections.
- Malaria is caused by a protist and spread by mosquitoes, which act as vectors.
- Rose black spot (fungal) and tobacco mosaic virus (viral) affect plants.
Plant Diseases
- Rose black spot causes dark spots and leaf drop; treated with fungicides.
- Tobacco mosaic virus inhibits chlorophyll production, reducing photosynthesis and stunting growth.
Body Defenses Against Infection
- The skin acts as a physical barrier against pathogens.
- Mucus in the nose and trachea traps pathogens.
- Stomach acid and digestive enzymes destroy ingested pathogens.
- White blood cells fight pathogens; lymphocytes make antitoxins and antibodies.
- Antibodies bind to pathogens' antigens, neutralizing them and marking them for destruction by phagocytes.
Immunity and Vaccination
- The immune system stores antibody "blueprints" for future defense against known pathogens (immunity).
- Vaccines contain dead or inactive pathogens to stimulate antibody production without causing disease.
- mRNA vaccines prompt cells to produce parts of a virus to trigger immunity.
Antibiotics and Drug Development
- Antibiotics kill bacteria but not viruses; penicillin is the first antibiotic.
- Overuse of antibiotics can lead to bacterial resistance.
- Drugs can be derived from plants (e.g., aspirin from willow trees) or synthesized.
- New drugs are tested in lab, animal, and human trials (using placebos and blind/double-blind methods).
Monoclonal Antibodies
- Monoclonal antibodies are produced from cloned hybridoma cells to target specific antigens.
- Used for treatment, diagnosis, and laboratory detection by binding to target molecules.
- Side effects can be more severe than expected.
Key Terms & Definitions
- Pathogen — a microorganism that causes disease.
- Antigen — a molecule on a pathogen triggering an immune response.
- Antibody — a protein made by lymphocytes that binds to antigens.
- Vaccine — a preparation that trains the immune system using dead/inactive pathogens.
- Vector — an organism that spreads disease, such as a mosquito.
- Monoclonal Antibody — identical antibodies made from a single cell clone.
- Hybridoma — a cell formed by fusing a lymphocyte with a tumor cell for antibody production.
Action Items / Next Steps
- Review details of different pathogens and the diseases they cause.
- Study key terms and definitions.
- Prepare for a discussion on vaccine development and drug testing methods.