B3

Communicable disease

Pathogens- These are microorganisms that enter the body and cause disease. Usually a communicable disease

Communicable disease- A disease that can be easily spread from organism to organism, these affect both plants and animals

Bacteria-

  • Cells 1/100th the size of normal body cells

  • reproduce very quickly

  • produce toxins that damage your cells and tissues

Viruses-

  • 1/100th the size of bacterium,

  • reproduce quickly,

  • living inside your cells,

  • forcing it to reproduce copies of itself

  • until the cell bursts causing cell damage, which makes you ill

Protists-

  • Simple eukaryotic organisms

  • that live on or inside other organisms,

  • can cause damage

Fungi-

  • Some single celled,

  • others grow hyphae

  • which can penetrate skin and cause diseases

  • can produce spores which can spread to other plants or animals

Pathogens can spread via:

  • Water- Drinking it e.g. Cholera

  • Air- Carried through breathed though droplets in the air in sneezes or coughs

  • Direct contact- e.g. athletes foot

Viral, Fungal, Protist and bacterial Diseases

Virus- Measles:

  • Spread through droplets in persons cough or sneeze

  • Causes red skin rash and fever

  • Can lead to complications such as pneumonia or encephalitis (Brain infection)

  • Most people are vaccinated against it when young

Virus- HIV:

  • Can spread as an STD or when people share needles when taking drugs

  • Initially causes flu symptoms

  • Then causes goes dormant as it attacks immune cells

  • Then immune system breaks down unable to cope with other infections or cancers

  • Causing AIDS

Virus- Tobacco Mosaic Virus (TMV):

  • Only affects plants

  • Causes a discolouration in leaves

  • Which interferes with photosynthesis

Fungal disease- Black Rose Spot

  • Causes black or purple spots

  • Turning leaves yellow and making them drop off

  • Causing a decrease in rate of photosynthesis

  • Stunting plant growth

  • Can be treated by stripping affected leaves

  • And using fungicides

  • and cleaning disposal equipment

Protist disease- Malaria:

  • Protist uses mosquito as vector (living inside or on it)

  • Mosquito feeds on other animals

  • inserting protist into the animals blood stream

  • causing repeating episodes of fever

  • spread can be reduced using insecticides and mosquito nets

  • Or stopping mosquitos from breeding

Bacterial disease- Salmonella

  • This causes food poisoning

  • Symptoms include: fever, stomach cramps, vomiting, diarrhoea

  • It is contracted by ingesting infected food

  • Such as food that has been prepared in unhygienic conditions

  • Or poultry that where infected whilst they were alive

  • It can be prevented by vaccinating poultry and preparing food with good hygiene standards

Bacterial disease- Gonorrhoea

  • This is an STD, meaning that it is passed by sexual contact

  • This causes pain when urinating and thick yellow discharge

  • To stop this you can treat it with antibiotics

  • (but there are now anti-biotic resistant strains)

  • Or use barrier methods of contraception such as condoms

Preventing disease- this can be done by:

  • Being hygienic-

    • Washing hands before preparing food

    • Washing hands after sneezing

    • Using a mask around infected people

    • Thoroughly Cooking food

  • Destroying vectors-

    • Killing mosquitos and other protist carriers

    • Using insecticides against insects

  • Isolating infected

    • QUARANTINEEE

    • using a mask

    • Wearing gloves

    • Sops people passing it on

  • Vaccination

    • Stops people becoming infected and passing it on

    • Causing herd immunity

    • Where vaccinated people can’t pass it on to other non-vaccinated people as they can’t contract it as easily

Disease defence systems

  • The skin: acts as a barrier protecting against pathogens

    • and secretes antimicrobial substances, killing pathogens

  • The Nose: Has hairs + mucus which trap large particles that may contain pathogens

  • The trachea and bronchi: Secrete mucus to trap pathogens

    • And are lined with Cilla which waft mucus to the back of the throat

  • The stomach- Has Hydrochloric acid which kills pathogens coming from the mouth

  • The immune system attacks pathogens in a process called phagocytosis

    • This is where the white blood cell engulfs the pathogen

  • They also produce anti-toxins which neutralise the toxins produced by pathogens

  • And they produce antibodies:

    • Which are produced when a white blood cell notices a pathogen

    • This is because all cells have unique molecules on their surface called antigens

    • If the white blood cell discovers a foreign antigen it produces antibodies

    • Which lock onto and attack the foreign object

    • Via binding onto the foreign antigen

    • The body remembers the antigen and what killed it causing a natural immunity

Vaccination

  • This takes advantage of the body remembering antibodies and antigens

  • By injecting someone with a dead or inactive form of the pathogen

  • Which lets the body create antibodies for the pathogen and learn how to kill it

  • Making the process of producing the necessary antibodies much faster

  • Causing immunity

Pros:

  • This has helped stop once common communicable diseases

  • Such as: Measles, whooping cough, rubella, mumps, tetanus, smallpox and poli

    • With cases of polio being reduced by 99% and small pox almost irradicated

  • This has greatly lowered the amount of epidemics

Cons:

  • These don’t always give you immunity, only working sometimes

  • These can give you a bad reaction e.g.: swelling, fever, seizure, but these are rare

Drugs

There are:

  • Pain killers- e.g. Aspirin which just relieve the pain and other symptoms

  • Antibiotics- e.g. Penicillin, which kills/ prevents the growth of bacteria

    • With different ones killing different bacteria

    • But these don’t kill viruses

    • As they use your body cells to reproduce

    • So there’s no way to kill the virus without killing your body cells too

Antibiotic Immunity:

  • Bacteria mutate

  • Meaning antibiotic strands can form

  • And as the non-resistant strands are killed

  • The resistant strands reproduce

  • Causing the same problem all over agian

  • e.g. MRSA

  • To stop this people should

    • Finish antibiotic courses, to make sure that bacteria doesn’t have the time of day to mutate

    • Not over prescribe- The more you prescribe something the quicker it mutates

    • So, don’t prescribe things unless they are absolutely needed

Plants

Plants produce lots of our medicines and antibiotics (Alexander Fleming discovered antibiotics)

  • Aspirin the painkiller, comes from willow trees

  • Digitalis used to treat heart conditions, Comes from foxgloves a plant

Developing drugs

This anime has 3 arcs, but first some lore on key quotes:

Efficacy- Weather the drug produces the desired effect or not

Toxicity- How harmful it is to people

Placebo- A similar substance, that doesn’t do anything

Peer review- When other scientists review data, and copy experiments to see if the results are repeatable, or if the claims are false or not

Optimum dosage- The best amount to give to someone and its concentration, the one with the highest effectiveness and lowest amount of side effects

1.) Preclinical TESTING- On Living Cells

  • This is when you test the drug on human cells and tissues

  • This, however, doesn’t tell you the affect on whole organ systems

2.) Preclinical TESTING- On Living Animals

  • This to test the efficacy, toxicity, and optimum dosage

  • This has to be done on at least 2 live mammals e.g. mice or rabbits in the UK

  • Some may think that this is unethical others think its the safest way

3.) Clinical Trials- On Living humans

  • If it passes the first to arcs then it moves onto this

  • First on health people in low doses

  • To see if it has side effects on people who are healthy

  • This dosage is gradually increases

  • Then the optimum dosage is found

  • Then a does is given to 2 groups of patients

  • one is given a placebo, and the other is given the actual drug

  • This is often done double blind where neither the doctors or patients know who had what

  • Which removes bias as results are being recorded

  • These results and claims, and drugs are then peer reviewed before being published to prevent false claims

Monoclonal Antibodies

Antibody- This is a certain protein that helps fight infection locking onto the antigen of a specific pathogen

Antigen- These are the unique substances on the outside of cells that the immune system uses to identify pathogen from body cell (basically friend from foe)

B-lymphocyte- This is a certain type of blood cell that produces antibodies to help fight pathogens

Monoclonal antibodies- Antibodies made from B-lymphocyte clones, these are all identical

Fast dividing tumour cells- Used in the process for making fast diving lymphocytes

HCG- A hormone found only in the urine of pregnant women

Hybridoma- This is a B-lymphocyte, tumour cell fusion that creates multiple Fast diving B-lymphocytes, that all produce the same antibodies (MONOCLONAL ANTIBODIES) which can be collected and purified

Pipeline:

  1. Usually a mouse is injected with a certain antigen

  2. The mouse makes B-lymphocytes that make antibodies that target the antigen

  3. These B-lymphocytes are taken from the mouse

  4. And are fused with fast dividing tumour cells from a lab

  5. Creating a hybridoma which produces the desired monoclonal antibodies

  6. Which can be collected and purified

These monoclonal antibodies can be used in certain applications such as~

Pregnancy Tests: (AAAHHHHH NOOOOOO)

  • Antibodies attached to blue dye

  • The test strip has more antibodies wired to the hormone

  • If the test is positive:

    • The urine moves up the stick carrying the hormone

    • Theses bind to the antibodies with the blue dye

    • The dye and the hormones bind through the antibodies turning the strip blue

  • If it is negative this means

    • The there is no hormone to bind

CANCER CELLZ:

  • Cancer cells have a different type of antibody called a tumour marker

  • Monoclonal Antibodies can be made to bind to these and be attacked to a toxic drug

  • so they target the cancer with the drug or radioactive substance

  • Leaving healthy body cells untouched

Find substances:

  • They are made to bind to the specific substance that your looking for

  • Then they bind to a fluorescent dye

  • If the substance is present, the antibodies attach to them, being detected via the dye

ADV

  • They help with cancer treatments and damage body cells less the chemotherapy

  • And radiotherapy

  • However cause side effects such as:

    • fever

    • Vomiting

    • Low blood pressure

Plant Diseases and Defences

Plants need:

  • Nitrates to create proteins for growth

  • Nitrate deficiency causes stunted growth

  • Magnesium for making chlorophyll

  • Magnesium deficiency causes chlorosis and yellow leaves

Plants can be damaged by:

  • Viral diseases

  • Bacterial diseases

  • Fungal pathogens

  • Insect infestations E.g. aphids

Common signs are:

  • Stunted growth

  • Spots on the leaves

  • Patches of decay / rot

  • Abnormal growths and lumps

  • Malformed stems or leaves

  • Discolorations

  • Visible pests

These specific signs can be identified by:

  • Using a gardening manual

  • Using a gardening website

  • Using a testing kit with monoclonal antibodies

  • Taking the plant to a laboratory where scientists can identify the pathogen

Physical plant defences

  • Waxy cuticle- A barrier to stop pathogens from entering

  • Cell walls- Made of cellulose, another physical barrier

  • Bark- A layer of dead cells around stems

Chemical defences:

  • Poisons- Deters herbivores from eating the plant

    • e.g. tobacco, foxgloves, deadly night shades

  • Antibacterial chemicals-

    • E.g. mint plants, witch hazel

Mechanical defences

  • Thorns + hairs

  • Mimic organisms

  • Drooping or curling when touched to knock off insects

NEEEEEXXXXXXXXXT