B4 Biodiversity, evolution and disease

• Animal transmission modes include touching, kissing, contact with cut skin, sexual contact, animal bites, sharing needles, and cuts in the skin.
• Plant transmission modes can be either direct or indirect.
• Plants defend themselves against pathogens by producing barriers such as bark, waxy cuticles, antibacterial chemicals, and proteins, and can repel insects which are often vectors of pathogens.
• Plants also have physical defenses to prevent pathogens from spreading between their cells once they become infected.
• Animal responses to pathogens include primary and secondary lines of defense.
• The primary line of defense in animals is non-specific and includes the skin, mucous membranes, and lysozymes.
• The secondary line of defense in animals includes phagocytes which are white blood cells that engulf and destroy pathogens.
• Verses are the same concept but on land, so these areas are actively managed to conserve the wildlife, involving removing organisms from their natural habitat to try and protect them.
• Botanical Gardens, seed banks, and captive breeding are used to conserve a wide range of plant species.
• Phylogenetic classification arranges species into groups according to their evolutionary origins and relationships, indicating how closely related species are and how recent their shared common ancestor is.
• The Linnaeus classification hierarchy system consists of domain, kingdom, phylum, class, order, family, genus, and species, known as a hierarchy because there are small groups arranged into larger groups with no overlap between the groups.
• The binomial system, which uses two names, is universally used so that data on different species can be used.
• The binomial system gives an indication of how closely related different species are because if they're in the same genus, they must be closely related within that hierarchy classification system.
• The Linnaeus classification hierarchy system includes the prokaryote, protoctista, fungi, plantain, and Animalia.
• Changes in the classification systems have occurred as there have been advances in technology, as classification used to be based on physical appearances which could be misleading because members of the same species can look very different if they live in different habitats or members of different species can look very similar if they live in the same habitat.
• The accuracy of classification improved a lot when advances in genome sequencing and Immunology allowed for comparison of our molecular similarities and not just observable characteristics.
• Antibodies can help to destroy pathogens in three ways: agglutination, marking pathogens, and acting as an antitoxin.
• Agglutination is the clumping together of pathogens due to the antibodies binding to them and clumping them together, making it easier for phagocytes to locate and engulf them.
• Antibodies can act as opsonins, marking the antigen and making it more susceptible for phagocytosis.
• Antibodies can bind to toxins that are being produced by the pathogen and prevent the toxin from entering the cell and causing harm, classifying it as an antitoxin.
• The humoral response involves the production of antibodies by B cells, which are activated by T helper cells.
• The process of the humoral response begins with the cell mediated response, where activated T helper cells bind to B cells to activate them.
• The B cells are selected for clonal selection based on their complementary shape to the receptor on the helper T cell.
• Once the B cells have been selected correctly for clonal selection, they are activated by the release of interleuking chemicals from the T helper cell, causing them to rapidly divide by mitosis to make clones and differentiate into either memory B cells or plasma cells.
• The plasma cells are responsible for making the antibodies and those antibodies can then go on to perform one of the three roles discussed in the previous slide.
• The primary immune response is your first exposure to a pathogen, where it can take a few days for the lymphocytes to create enough of the complementary antibodies to destroy the pathogen and therefore you do get ill because the pathogen starts to cause damage.
• The secondary immune response is when you are reinfected with the same pathogen and you have been memory cells, as soon as those collide and bind with a complementary shape antigen to their receptor they can differentiate into the plasma cells and make large amounts of antibodies rapidly, so the pathogen gets destroyed before it can cause any damage or minimal damage and therefore you won't have any symptoms or you'll have very minimal symptoms.
• Active immunity involves being exposed to the pathogen or the antigen so that means your body has made plasma cells and memory B cells and you do have long-term immunity.
• Passive immunity is when antibodies are introduced directly into you so the pathogen itself doesn't enter your body, so no plasma cells or memory cells have been made and therefore you don't have any long-term immunity.
• Natural immunity is when you have been infected and you've created memory cells.
• Artificial immunity is through the introduction of a weakened version of the pathogen or the antigen through a vaccine.
• An antigen is typically a protein molecule on the cell surface membrane of a non-self cell that triggers the immune response and the production of antibodies.
• Autoimmune diseases are when the immune system identifies own body cells as non-self or foreign and therefore it triggers the immune response and starts to destroy healthy body cells.
• Examples of autoimmune diseases include rheumatoid arthritis and lupus.
• Rheumatoid arthritis is when the immune system attacks the cartilage in joints, causing inflammation and pain in the affected joints.
• Lupus causes inflammation to the joints, skin, organs, and causes fatigue.
• There is no cure for either of these diseases but anti-inflammatory drugs such as steroids and Pain Relief can be taken to relieve symptoms.
• Immunization or vaccine is a form of artificial active immunity where antigens or small amounts of attenuated pathogen are injected into you to trigger a primary immune response.
• Vaccines provide protection for an individual and entire populations against disease.
• Vaccines are not always effective in the long term and there are booster vaccines to prevent the spread of pathogens that have produced a different shaped antigen.