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Biology Topic 3 Infection and Response - Coggle Diagram
Biology Topic 3 Infection and Response
Plants Defences
Physical
Waxy cuticle, cell walls stop pathogen entering.
Mechanical
Thorns, curling up to prevent being eaten.
Chemical
Some plants produce toxins and antibacterial.
Human Defence Systems
Immune System
White Blood Cells: Produce antibodies or engulf pathogens.
Pathogens are identified by white blood cells by the proteins on their surfaces- antigens.
Phagocytes
Phagocytes engulf and digest the pathogen. This is called phagocytosis.
Lymphocytes 1.
Antibody production- Specific antibodies are needed to destroy a pathogen which takes time so an infection can occur. If the person is infected with the same pathogen twice they already have antibodies to destroy it.
2.
Antitoxin production- Antitoxins are a type of antibodies that are specifically designed to counteract the toxins produced by bacteria.
Non-specific Defence systems
Nose
Nasal hairs, sticky mucus, cilia prevent pathogens entering through the nostrils.
Trachea and Bronchus
lined with sticky mucus to trap dust and pathogens. Cilia move the mucus upwards to be swallowed.
Stomach Acid
ph1 kills most ingested pathogens.
Skin
hard to penetrate waterproof barrier, glands secrete oils which kill microbes.
Communicable Diseases
Virus
Measles
Leads to fever, red skin rash. Droplet infection transmitted by coughing or sneezing. Control spread by vaccination.
HIV
Leads to initial flu like symptoms but can leave huge damage to immune system. Sexually transmitted. Prevent using condoms and anti-retroviral drugs.
Tobacco Mosaic Virus
Leads to mosaic pattern on leaves. Enters via wounds in epidermal from pests. Prevent by removing damaged leaves and control the pests.
Bacteria
Salmonella
Leads to fever, cramp, vomiting, diarrhoea. Transmitted by uncooked food or bad food prep. Prevent by better food hygiene, vaccinate poultry, wash hands.
Gonorrhoea
Leads to green discharge from vagina or penis, Sexually transmitted. Prevent by using condoms and treat with antibiotics.
Protists
Malaria
Recurrent fever. Transmitted by mosquitoes. Prevent by using mosquito nets or stop the breeding of them.
Fungus
Rose Black Spot
Purple black spots on leaves. Transmitted by spores carried via water or wind. To control spread pick off leaves that are infected or spray with fungicide.
Types of Pathogens
Protists
e.g. malaria, dysentery, sleeping sickness. Membrane bound organelles. Usually single cell.
Virus
e.g. cold, influenza, HIV. DNA or RNA surrounded by a protein coat.
Fungi
e.g. athletes' foot, thrush, rose black spot. Membrane bound organelles, cell wall made of chitin. Single-celled or multi-cellular.
Bacteria
e.g. TB, salmonella, gonorrhoea. No membrane bound organelles, no chloroplasts, mitochondria or nucleus. Cell wall. Single celled.
Detection of Plant Disease
Stunted growth, spots on leaves, area of decay, growths, malformed leaves, discolouration, presence of pests.
To identify which disease: use a gardener's manual, laboratory test, testing kit using monoclonal antibodies.
Magnesium ions
needed to make chlorophyll- not enough leads to chlorosis which gives the plant yellow leaves.
Nitrate ions
needed for protein synthesis- not enough leads to stunted growth.
Discovery and Drug Development
Originally drugs were extracted from plants.
Penicillin
Extracted from mould and used as an antibiotic.
Aspirin
Extracted from willow bark and used as an anti-inflammatory and pain killer.
Digitalis
Extracted from foxglove plants and used as a heart drug.
Bacteria can mutate so they can become resistant to antibiotics.
Testing
Efficacy
Make sure it works.
Toxicity
Check that the drug isn't poisonous.
Dosage
Finding the right amount to take.
Preclinical Trials
trials have to be taken on animals before humans.
Clinical Trials
1.
Healthy volunteers take a small dosage to see if it's safe and record any side effects.
2.
A small number of patients try a low dosage to see if it works.
3.
A large number of patients are given different dosages to find the optimum dosage.
4.
A double blind trial will occur (to avoid bias the patients and scientists don't know who's taken the drug or placebo (contains no active ingredients) until the end of the test).
Antibiotics and painkillers
Antibiotics
e.g. penicillin. Kill infective bacteria. Specific bacterial infections require specific antibiotics.
Pain killers
e.g. paracetamol, aspirin, ibuprofen. Designed to reduce the symptoms of an infection not kill it.
Antibiotics can't be used against viral infections. Viral infections are hard to treat because viruses live inside the cells so killing those would be harmful to the body.
Vaccination
Used to immunise a large proportion of a population to prevent the spread. A small amount of dead or inactive form of the pathogen.
First infection by pathogen: White blood cells detect the pathogen and release antibodies into the blood.
Re-infection by the same pathogen: White blood cells detect the pathogen and antibodies are made much quicker and in fast amounts.
Monoclonal Antibodies
Production
1.
A mouse is injected with a pathogen.
2.
Lymphocytes produce antibodies.
3.
Lymphocytes are extracted from the mouse and are fused with rapidly growing mouse tumour cells.
4.
The new cells are called hybridomas.
5.
The hybridomas divide rapidly and release lots of antibodies which are then collected.
Uses
Diagnosis
e.g. pregnancy test- measures the level of hormones.
Detecting Pathogens
Can detect very small quantities of chemicals in blood.
Detecting Molecules
Fluorescent dyes can be attached so it can be seen inside cells and tissues.
Treatment
Bound to radioactive substance, toxic drug or chemical; cancer cells are targeted and body cells are unharmed.