GCSE Biology- B3 infection and response

pathogens

microorganisms that cause disease by entering the body

bacteria

small cells that reproduce quickly in the body and produce toxins that make you feel ill, damaging cells and tissues.

viruses

smaller than bacteria, replicate inside cells, then bursting and releasing more viruses.

protists

eukaryotes, could carry parasites and live on or inside other organisms, often carried by a vector

vector

any organism that can spread disease.

fungi

sometimes singled celled, often has a hyphae that grow and penetrate human skin or surfaces of plants. can produce spores which can spread to other plants

how can pathogens be spread

air, water, direct contact

example of pathogen spread by water

cholera

example of pathogen spread by air

influenza

example of pathogen spread by direct contact

Athlete's foot

examples of viral diseases

measles, HIV, tobacco mosaic virus

example of fungal diseases

Rose black spot

example of protist disease

malaria

example of bacterial diseases

Salmonella, gonorrhoea

How to prevent spread of bacterial diseases

being hygienic, destroying vectors, isolation, vaccination

nitrate deficiency symptoms for plants

stunted growth

magnesium deficiency symptoms for plants

yellowed leaves/chlorosis

common symptoms of diseased plants

stunted/abnormal growth, spots on leaves, patches of decay, malformed or discoloured leaves and stems

physical defence systems of pathogens in plants

waxy cuticle, cell walls, layer of dead cells

mechanical defence systems of pathogens in plants

thorns, hairs, mimicry, leaves that droop or curl

defence systems of pathogens in humans

skin, hair and mucus, trachea and bronchi, cilia, hydrochloric acid

human immune system

kills any pathogens entering body- white blood cells: phagocytosis, antitoxins produced to neutralise toxins, also produce antibodies which lock onto surface of antigen outside of pathogen, white blood cells then destroy pathogen.

antibody

proteins produced by the immune system that can recognize and bind to specific antigens, such as viruses or bacteria, and help to neutralize or destroy them.

antigen

any substance that causes your body to produce antibodies against it

phagocytosis

phagocytes engulfing the pathogen and destroying it

vaccination

injecting a dead or inactive form of a pathogen to cause your body to produce antibodies, helping produce antibodies quicker when infected with the pathogen again

positives of vaccinations

control common communicable diseases, prevent epidemics

negatives of vaccinations

don't always work, can cause bad reaction in a rare instance

drugs that fight diseases

painkillers, antibiotics

antibiotics

kill bacteria causing disease; doesn't work on viruses as it lives inside cells

painkillers

relieve the pain and symptoms of disease but do not kill it

drug testing stages

1. preclinical testing with human cells and tissues, 2. preclinical testing with live animals, 3. clinical trials- testing on healthy human volunteers or patients with low doses

placebo

substance similar to drug but without any effect when taken

placebo effect

when patient thinks there is an effect although no treatment has taken place

blind trials

when the patients do not know if they received the drug or the placebo, but the doctors/physicians know.

double-blind trials

when both the doctor and patient do not know if they received the placebo or drug

drug

A chemical substance that is taken to cause changes in a person's body or behaviour

drugs from plants

chemicals produced by plants to defend themselves that can be used treat human diseases or help with symptoms

aspirin

drug made from willow trees

digitalis

drug made from foxglove

penicillin

antibiotic made from penicillium mould

where are new drugs made?

Made in laboratories in the pharmaceutical industry by chemists

antitoxins

antibodies against specific toxins

monoclonal antibodies

identical antibodies produced by B lymphocyte

monoclonal antibodies process

antigen injected into mouse, immunisation, immune cells isolated, antibody forming cells, hybridomas- fused cells of myeloma- tumour cells to antibodies, antibody produced hybridomas cloned, monoclonal antibodies produced

uses for monoclonal anitbodies

Pregnancy testing, treating diseases, research to find specific substances

Pregnancy testing using monoclonal antibodies

HCG hormone, found in women when pregnant binds to antibodies

treating diseases using monoclonal antibodies

anti-cancer drugs can be attached to monoclonal antibodies- kills cancer cells and not normal body cells

research to find specific substances using monoclonal antibodies

used to bind hormones and chemicals to the blood to measure levels of specific substances

problems of using monoclonal antibodies

more side-effects than originally thought, eg. fever, vomiting, low blood pressure. Not used by doctors as much as first thought

what are drugs tested for

efficacy (how well does the drug do its job), toxicity (threat to human/animal), dose (how much is needed)