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Topic 3 Infection And Response By Bethan Poole (3.1 Communicable Diseases,…
Topic 3 Infection And Response
By Bethan Poole
3.1 Communicable Diseases
3.1.5 Protist Diseases
Single-celled organisms- eukaryotic
Malaria
Uses a particular type of mosquito as a vector- passes on when someones bitten
Effects
Severe fever reoccurs and can be fatal
Prevention
Stop people being bitten e.g. killing the mosquitoes or use mosquito nets
3.1.6 Human Defence System
Non-Specific defense systems
Nose
Trachea and Bronchi
Skin
Stomach
Goblet cells- Produce mucus-traps dirt and bacteria
Immune System
White Blood Cells
Phagocytosis
Pathogen surrounded, engulfed and digested
Antibodies
Attach to bacterium's antigens
Antitoxins
Neutralise the bacterium's toxins
3.1.4 Fungal Diseases
Rose Black Spot
Spread by spores carried from plant to plant
Purple or black spots develop on leaves, often turn yellow and drop early
Loss of leaves will stunt growth- photosynthesis reduced
Treat- using fungacides and removing and destroying affected leaves
3.1.7 Vaccination
Contain a small number of dead or weakened pathogen particles
Stimulates production of antibodies and memory cells against the target pathogen
If they are later infected by the same pathogen, their immune system can destroy it quickly
Herd Immunity
When a high percentage of the population are immune to a disease it provides pprotection for those who are not vaccined or immune to it
3.1.3 Bacterial Diseases
May damage cells directly or produce toxins that damage tissues
Salmonella
Type of food poisoning
Bacteria ingested in food- may not have been cooked properly or not prepared i hygenic conditions
Bacteria secrete toxins
Fever
Abdominal pain
Cramps
Vomitting
Diarrhoea
Chicken and eggs can contain the bacterica- vaccinated to control spread
Gonorrhoea
STD
Symptoms
Thick yellow or green discharge from vagina or penis
Pain when urinating
Used to be treated with penicillin but resistant strains have now appeared
Prevent- Use of barrier method of contraception e.g. a condom
3.1.8 Antibiotics And Painkillers
Kill bacteria inside the body
Can't kill viruses
Painkillers and other medicines are used to treat the symptoms
Dfficult to develop drugs that kill viruses without damaging the body's tissues
Certain antibiotics perscribed for certain diseases
Use of antibiotics- greatly decreased numbers of deaths from infections
Bacterial strains to antibiotics are increasing though
Have to take full course of antibiotics - otherwise bacteria mutates and creates new strains
3.1.2 Viral Diseases
Viruses reproduce rapidly in body cells - damage cells they reproduce in
Measles
Symptoms- Fever, Red skin rash
Spread by droplets in the air
Can be fatal- Most young children vaccinated
HIV
Causes AIDS
Spread by sexual contact or exchange of body fluids
At first causes flu-like symptoms
If untreated enters the lymph nodes and attacks body's immune cells
Antiviral drugs can delay this
Late stage HIV or AIDS body can't fight off infections or cancers
Tobacco Mosaic Virus
Widespread plant pathogen - affects many plant species including tomatoes
Causes mosaic pattern on leaves
Reduces rate of photsynthesis and therefore growth
3.1.9 Discovery And Development Of Drugs
Constant demand for new drugs
New painkillers developed to treat symptoms but not kill the pathogens
Antiviral drugs needed that will kill viruses without damaging body's tissues
New antibiotics needed as resistant strains of the bacteria develop
Traditionally drugs extracted from plants and miroorganisms
Aspirin
-Painkiller, originates from willow
Penicillin
-Discovered by Alexander Fleeming, Penicillin mould
Digitalis
- Heart drug, orginates from foxgloves
Now most drugs are made by chemists in th pharmaceutical industry
New drugs have to be tested and trialed before used
Check they are safe and efficient
Tested for toxicity, efficancy, dose
1st testing in labs using cells, tissues and live animals-
PRECLINICAL
Then tested on healthy volunteers and patients-
CLINICAL
At start of cinical trial very low doses of the drug given- if drug safe further clinical trials to find optimum dose
Double Blind Trials
- Doctor and patient not told who's given medication and who's given a placebo- removes bias
Placebo
- looks like drug but isn't it
3.1.1 Communicable Diseases
Organisms that cause infectious diease called
Pathogens
Virus
Protozoa
Fungi
Bacteria
How are they spread
Food and water
Insect Bites
Direct Contact
Airbourne Droplets
Indirect Contact
Reducing Spread of Infectious Diseases
Simple Hygiene Measures
Destroying Vectors
Isolating infected individuals
Vaccination
3.2 Monoclonal Antibodies (HT Only)
3.2.1 Producing Monoclonal antibodies
Produced from a single cell that's divided to make many cloned copies of itself
Bind to only one type of antigen so they can be used to target a specific chemical or specific cells in the body
Produced by combining mouse cells and tumour cells to make a hybridoma
Cancer cells used as they are very effective multipliers
Needed as White blood cells only make one type of antibody- once they have started producig antibodies it can't divide by mitosis
Mouse injected with an antigen (pathogen) to stimulate an immune response
Mouses WBC (lymphocyte) respond by making the right antibodies
Mouse blood extracted an WBC extractd by pouring them over beads that atract the correct WBC
WBC fused with cancer cells- test tube/ petridish- Hybridoma cells formed, will multiply and produce the right antibodies
3.2.2 Uses of Monoclonal Antibodies
Pregnancy Test Kits
Identify the small levels of a hormone
Locate blood clots
Bind to the clots
Treating cancer
Bind to cancerous cells- helps their immune system attack them and bind to radioactive substances, toxic drugs or chemicals which stop cells growing nd dividing- delivers substance to cancer cels without harming other cells
In labs
Measure hormone levels and other chemicals in blood or to detect pathogens
Not widely used- to many side effects
In research
Locate or identify specific molecules in cell or tissue by binding to them with a flurescent dye
3.3 Plant Disease (HT Only)
3.3.1 Detection And Identification Of Plant Diseases
Diesease Detection
Stunted Growth
Spots on leaves
Areas of Decay (Rot)
Malformed stems or leaves
Growths
Discolouration
Presence of pest
Identification
Gardening manual or website
taking infected plans to a lab to idnetify the pathogen
Testing kits that contain monoclonal antibodies
Plants can be infected by communicable or non-communicable viral,bacterial or fungal pathogen as well as by insects
Tobacco Mosaic Virus
Infects many plants including tobacco and tomato
Produces mosaic pattern of leaves , reuces chlorophyll- reduces growth and photosynthesis
Rose black Spot
Causes black spots on leaves, turn yellow and drop early
Reduce photosynthesis
Spread by water/wind
Treat with fungicid or remove affected leaves
Aphids
Small Insects- feed from phloem, take sugar away from plant
Ion Deficiency
Stunted growth- nitrate deficiency- reduced protein synthesis
Chlorosis- Magnesium deficiency- magnesium needed to make chlorphyll
3.3.2 Plants Defense Responses
Phyical
Cellulose cell walls
Layers of dead cells around stem
Tough waxy cuticle
Mechanical
Leaves that droop or curl when touched
Mimicry to trick animals
Thorns and hairs
Chemical
Antibacterial chemicals
Poisons to deter herbivores
