4.1.1 Flashcards
What are the 4 types of pathogens that cause communicable diseases?
Bacteria
Viruses
Protoctista
Fungi
What are the three subsections of direct transmission in animals? Provide examples of each.
Direct contact or any contact with the body fluid of another person.
Inoculation - break in the skin, animal bite, needle sharing
Ingestion - contaminated food or drink, transfer of pathogens from hand to mouth
What are the three subsections of indirect transmission in animals?
Fomites - inanimate objects e.g. bedding, socks, cosmetics
Droplet infection
Vectors - mosquitoes, rats, bats
What increases the probability of catching a communicable disease in animals?
Overcrowded living and working conditions
Poor nutrition
Compromised immune system
Climate change
Socioeconomic factors - lack of trained health workers
What are the two subsections of indirect transmission in plants?
Soil contamination. Bacteria, viruses, reproductive spores from Protoctista or fungi.
Vectors
Name 4 vectors in indirect transmission of plant pathogens.
Wind
Bacteria, viruses, fungal spores
Water
Spores swim on the surface film of water on leaves
Animals
Insects and birds carry pathogens and spores. Aphids inoculate pathogens directly into plants.
Humans
Pathogens and spores are transmitted on hands, clothing, fomites, and by transporting plants around the world.
What can affect the transmission of communicable diseases in plants?
Planting crops suspectable to diseases
Overcrowding means plants touch each other
Poor mineral nutrition reduces resistance
Damp, warm conditions increases survival and spread
Climate change - increased rain and wind promote spread
What two categories of defence do plants have?
Physicial
Chemical
What physical defence does a plant use?
Production of high levels of a polysaccharide called callose.
Deposited between cell walls.
Lignin is then added.
Callose blocks sieve plates, sealing off the infected area
Callose is deposited in the plasmodesmata between infected cells and neighbouring cells.
What is the purpose of chemicals in plant defence?
Repel insect vectors - pine resin, citronella
Kill invading pathogens - insecticides, antibacterial compounds, antifungal compounds
What are the primary non-specific defences against pathogens in animals?
Skin - lots of healthy organisms that outcompete pathogens for space. Sebum inhibits the growth of pathogens.
Mucous membranes protect the respiratory system by trapping pathogens
Blood clotting
Wound repair
Inflammation
Explain how the inflammatory response works.
Mast cells are activated in damaged tissues.
Histamines and Cytokines are released.
Histamines make the blood vessels dilate.
Blood vessel walls become more leaky so blood plasma is forced out.
Tissue fluid causes swelling. Pain and heat.
Cytokines attract phagocytes.
Draw and label an antibody.
What are antibodies?
Y shaped glycoproteins called immunoglobulins which bind to a specific antigen on the pathogen or toxin.
Explain the protein structure of an antibody.
Two identical long polypeptide chains called heavy chains and two much smaller identical chains.
The chains are held together by disulfide bridges.
Disulfide bridges also exist within the polypeptide chains, holding them in shape.
What is an autoimmune disease?
A disease where the immune stop recognising ‘self’ cells and starts to attack healthy body tissue.
Provide an example of one autoimmune disease and its effect.
Lupus. Affects the skin and joints. Causes fatigue. Can attack any organ in the body
No cure
Treated with anti-inflammatory drugs, steroids, immunosuppressants
Immunity can occur naturally in the body. Provide two examples.
After exposure to a pathogen for the first time. T and B memory cells are produced.
Newborn babies are provided with some antibodies from the mother via the placenta.
Colostrum from the breast provides more antibodies.
How does artificial passive immunity work?
Antibodies are extracted from another individual and injected into the bloodstream of another individual.
It does not last long.
How does artificial active immunity work?
The immune system is stimulated to make its own antibodies by injecting a safe form of the antigen.
How are antigens made safe to be used as vaccinations? (5)
Killed or inactivated bacteria or virus
An attenuated strain of bacteria or virus
Toxins molecules that have been altered and detoxified
Isolated antigens extracted from the pathogen
Genetically engineered antigens
What do vaccines do?
They give long term immunity to many diseases.
When vaccines are deployed to prevent epidemics, what sometimes has to happen?
They may have to be changed regularly to remain effective.
Provide three examples of drugs and where they are derived from.
Penicillin - Antibiotic - originally extracted from mould on melons
Aspirin - Painkiller, Anti-coagulant, anti-inflammatory - compounds from willow bark
Digoxin - Heart drug - originally extracted from foxgloves
What is the process of combining known drug actions with personal genetic material called?
Pharmacogenetics
What are the two forms of synthetic biology?
Biological factories - using genetic engineering to grow bacteria that is used in drugs and that would otherwise be too expensive or not available.
Nanotechnology - tiny, non-natural particles are used for biological purposes. e.g. Drug delivery
How do antibiotics work?
Selective toxicity - They interfere with the metabolism of the bacteria without affecting the metabolism of the human cells.
How can antibiotic resistance be reduced?
Minimise the use of antibiotics
Ensure a course of antibiotics is completed, reducing the chance of resistance individuals surviving
Good hygiene in hospitals to reduce the spread of antibiotic-resistant strains
Provide two examples of antibiotic-resistant bacteria.
MRSA
C. difficile
