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Infection and Response part 1 – Viral diseasesExamples of Viral DiseasesMeasles Symptoms of fever and a red skin rash Can be fatal if complications occur Spread by inhaling droplets containing the virus from sneezes and coughs It is controlled by vaccinating young childrenHIV Initially causes a flu-like illness and spread by sexual contact or exchangeof body fluids such as blood when drug users share needles Unless HIV is successfully controlled with antiretroviral drugs, the viruswill attack the body’s immune cells Late stage HIV or AIDS occurs when the body’s immune system can nolonger deal with other infections or cancersTobacco Mosaic virus Common plant virus which enters through a damaged epidermis Seen as a distinct mosaic discolouration pattern on the leaves Affects growth as photosynthesis cannot occur as efficiently Control by removing affected leaves and destroying pests which causedinitial epidermal damage

Infection and Response part 1 – Bacterial diseasesExamples of Bacterial DiseasesSalmonella Salmonella food poisoning is spread by bacteria ingested infood or on food prepared in unhygienic conditions. Bacteria secrete toxins and cause symptoms including fever,abdominal cramps, diarrhoea and vomiting. In the UK, poultry are vaccinated against salmonella tocontrol the spread of the disease.Gonorrhoea Sexually transmitted disease (STD) caused by bacteria. Causes a thick yellow or green discharge from the penisor vagina and pain when urinating. Can be controlled with antibiotics or barrier methodsof contraception such as a condom. Easily treated with the antibiotic penicillin until manyresistant bacterial strains were found.

Infection and Response part 1 – Fungal and Protist diseasesExample of a Fungal DiseaseRose Black SpotExample of a Protist DiseaseMalaria The malaria causing protist is spread by Purple or black spots develop on leaves Leaves often turn yellow and drop off Photosynthesis is reduced. Growth isaffected as a result Fungal spores spread by wind or water Treat by removing infected leaves andburning them Spray with fungicide (a pesticide whichis used to kill fungus)mosquitoes feeding on infected bloodand then biting a human Mosquitoes are vectors as they pass onmalaria but do not suffer themselves Symptoms include recurrent fever andmalaria can be fatal Control the spread by preventingmosquitoes breeding and use mosquitonets to avoid being bitten

Infection and Response part 1 – Types of diseasesDiseaseMalariaSymptomRecurrent feverMethod oftransmissionControl spread of disease by:Caused by:By a vector from aninfected personPreventing breeding ofmosquitoes or use of a net toprevent being bittenProtistTobaccoMosaic VirusMosaic patternon leavesEnters via woundsin epidermiscaused by pestsRemove infected leaves andcontrol pests which aredamaging leavesVirusMeaslesFeverRed skin rashDroplet infectionfrom sneezes andcoughsChild VaccinationVirusGonorrhoeaGreen dischargefrom penis orvaginaDirect sexualcontact or bodyfluidsUse of a condom and treatinfected person withantibioticsBacteriaRose BlackSpotPurple blackspots on leavesSpores carried viawind or waterRemove infected leaves andspray with pesticideFungusSalmonellaFever, cramp,vomiting,diarrhoeaFood prepared inunhygienicconditions or notcooked properlyImprove food hygiene, washhands, vaccinate poultry, cookfood thoroughlyBacteria

QuestionIT!Communicable diseasesPart 1a Viral diseasesBacterial diseasesFungal diseasesProtist diseases

Infection and Response part 1 – QuestionIT1. What is the definition of a pathogen?2. List four types of micro-organism which can act as pathogens.3. Copy and complete the table to describe one similarity and onedifference between how bacteria and viruses act as s4. What do pathogens need from the host organism?5. Complete the sentences:HIV can be successfully controlled with drugs. If the immunesystem is badly damaged then may develop.

Infection and Response part 1 – QuestionIT6. Copy and complete the table for each disease.DiseaseSymptomMeaslesFeverRed skin rashFever, cramp,vomiting,diarrhoeaRose BlackSpotControl spread of diseaseby:BacteriaFood prepared inunhygienicconditions or notcooked properlyRemove infected leaves andspray with pesticideDirect sexualUse of a condom and treatcontact or body fluid infected person with antibioticsexchangeRecurrent feverMosaic patternon leavesCaused by:Child VaccinationPurple blackspots on leavesGonorrhoeaTobaccoMosaic VirusMethod oftransmissionBy a vector from aninfected personBacteriaPreventing breeding ofmosquitoes or use of a net toprevent being bittenVirus

Infection and Response part 1 – QuestionIT7. Look at this photograph.Suggest how pathogens could be transferred in this situation.What could people do to reduce the spread of pathogens?

AnswerIT!Communicable diseasesPart 1 Viral diseasesBacterial diseasesFungal diseasesProtist diseases

Infection and Response part 1 – AnswerIT1. What is the definition of a pathogen?Micro-organisms which cause infectious disease in animals & plants.2. List four types of micro-organism which can act as pathogens.Bacteria, Virus, Protist, Fungus.3. Copy and complete the table to describe one similarity and onedifference between how bacteria and viruses act as oduce rapidlyinside the bodyProduce toxins thatdamage tissuesVirusReproduce rapidlyinside the bodyLive and reproduceinside cells causing celldamage

Infection and Response – AnswerIT4. What do pathogens need from the host organism?Suitable conditions and nutrition to be able to grow and reproduce.5. Complete the sentences:HIV can be successfully controlled with antiretroviral drugs. If theimmune system is badly damaged then AIDS may develop.

Infection and Response part 1 – AnswerIT6. Copy and complete the table for each disease.DiseaseSymptomMethod oftransmissionControl spread by:Caused by:MeaslesFeverRed skin rashDroplet infectionfrom sneezes andcoughsChild VaccinationVirusSalmonellaFever, cramp,vomiting, diarrhoeaFood prepared inunhygienicconditions or notcooked properlyImprove food hygiene, washhands, vaccinate poultry,cook food thoroughlyBacteriaRose BlackSpotPurple black spotson leavesSpores carriedvia wind/waterRemove infected leaves and spraywith pesticideFungusGonorrhoeaGreen dischargefrom penis orvaginaDirect sexual contact Use of a condom and treator body fluidsinfected person with antibioticsBacteriaMalariaRecurrent feverBy a vector from aninfected personProtistTobaccoMosaic pattern onMosaic Virus leavesPreventing breeding of mosquitoesor use of a net to prevent beingbittenwounds inRemove infected leaves andepidermis caused control pests which areby pestsdamaging leavesVirus

Infection and Response part 1 – AnswerIT7. Look at this photograph.Suggest how pathogens could be transferred in this situation.What could people do to reduce the spread of pathogens?Direct contact bytouching acontaminatedsurface.Droplet infection ifsomeone sneezes orcoughs in the lift.Air - if fungal sporesare present.Could reduce thespread by:Hand over mouth ifcoughing and thenwashing.Use a tissue if sneezingand then dispose of itand wash hands.Washing hands withsoap after visiting thetoilet.Wear a face mask.

LearnIT!KnowIT!Infection and ResponsePart 1b Human defence systemsVaccinationAntibiotics and painkillersDiscovery and development of drugs

Infection and Response part 1 – Human Defence SystemsnoseNasal hairs, stickymucus and ciliaprevent pathogensentering throughthe nostrils.st o m a c hStomach acid (pH1)kills most ingestedpathogenstracheabronchusThe human bodyhas several nonspecific ways ofdefending itselffrom pathogensgetting in.videoRespiratory system islined with mucus to trapdust and pathogens. Ciliamove the mucus upwardsto be swallowed.skinHard to penetratewaterproof barrier. Glandssecrete oil which killmicrobes.

Infection and Response part 1 – Human Defence SystemsSometimes pathogens gain entry to the body.The immune system takes over to destroy them.The white blood cells are part of the immune system. Pathogens areidentified by white blood cells because they have different surfaceproteins. We call these surface proteins antigens.White blood cells act in 3 ways to defend the body:1. White blood cells (called phagocytes) engulf the pathogens and digestthem. This is called phagocytosis. Video phagocytes2. White blood cells (called lymphocytes) identify the antigen on thepathogen. They make specific antibodies to destroy the pathogens.This can take time and so an infection may occur. If a person isinfected again by the same pathogen, the white blood cells make theantibodies much faster. Video lymphocytes3. Bacteria may produce toxin (poison). White blood cells release specificantitoxins to neutralise the effect of the toxin.

Infection and Response part 1 – VaccinationCommunicable diseases can be dangerous leading to epidemics orpandemics. Vaccination can be used to enhance the immunesystem to reduce the chances of this happening. A vaccine containsa small amount of dead or inactive form of the pathogen that canbe introduced into the body.LymphocytepathogenWhite blood cellsdetect pathogens inthe vaccine.Antibodies are releasedinto the blood.Pathogens are destroyedby antibodies.

Infection and Response part 1 – VaccinationIf the body becomes re-infected with the same pathogen then thewhite blood cells are prepared.The white blood cells can respond much more quickly and makemore of the right type of antibodies much more quickly.White blood cellsdetect pathogens.Antibodies are madeand released into theblood much faster andin larger amounts.Pathogens are destroyedby the antibodies muchfaster.This means that the person is unlikely to suffer the symptoms of theharmful disease.Infection has been prevented by enhancing the immune system.

Infection and Response part 1 – AntibioticsAn antibiotic is a drug that helps to cure a bacterial disease bykilling the infective bacteria inside the body.Different bacterialinfections need adifferentantibiotic.Antibioticscannot be usedto treat viralpathogens.Penicillin is a wellknown antibioticmedicine.It is difficult to developdrugs to kill viruseswithout harming bodytissues because viruseslive and reproduce insidecells.Using antibioticshas greatly reduceddeaths.

Infection and Response part 1 – AntibioticsBacteria can mutate.Sometimes this makes them resistant to antibiotic drugs.The mutated bacteria are not killed. Increasing numbers of differentbacteria are becoming resistant and this is of concern.ARed bacteriacoloniesADisc soakedin antibioticClear nobacterialcoloniesBBacteria areresistant toantibiotic ABacteria arekilled byantibiotic B

Infection and Response part 1 –– PainkillersA doctor will not prescribe antibiotics for a viral infection as theydo not work.Antibiotics can only be used for bacterial infectionsPainkillers, steroids or anti inflammatory medicines can be used torelieve the symptoms of viral infections. Symptoms may include:fever, muscle ache, headache or a runny nose.Painkillersdo not kill pathogens.

QuestionIT!Infection and ResponsePart 1b Human defence systems Vaccination Antibiotics and painkillers

Infection and Response – QuestionIT1. Name and describe 3 ways the human body defends against theentry of pathogens.2. Draw a series of pictures to show how white blood cells carry outphagocytosis.3. What is an antigen?4. Why will the antibody produced for measles not be effective inother diseases?5. Why are dead or inactive pathogens used in a vaccine?6. What happens if the live pathogen invades the body after beingvaccinated?7. What is an antibiotic and what is it used for?

Infection and Response – QuestionIT8. Why is there a growing concern about bacterial resistance toantibiotics?9. Which one of these statements is true?Painkillers are used to treat the symptoms of a disease and kill thepathogens which cause it.Painkillers are used to kill the pathogens causing a disease.Painkillers are used to treat the symptoms of a disease but do not killthe pathogens.

AnswerIT!Infection and ResponsePart 1b Human defence systems Vaccination Antibiotics and painkillers

Infection and Response – AnswerIT1. Name and describe 3 ways the human body defends against theentry of pathogens. Skin – barrier, nose - nasal hairs , mucus and cilia,trachea & bronchi – mucus to catch, cilia to remove from lungs,stomach - HCl acid kills.2. Draw a series of pictures to show how white blood cells carry outphagocytosis. Diagram of white blood cell moving towards andengulfing foreign body and then adding digestive enzymes.3. What is an antigen? A protein on the surface of a pathogen.4. Why will the antibody produced for measles not be effective in otherdiseases? Antibody has a specific shape which fits with a specificantigen.

Infection and Response – AnswerIT5. Why are dead or inactive pathogens used in a vaccine?To stimulate white blood cells to make antibodies without causing thedisease.6. What happens if the live pathogen invades the body after beingvaccinated?White blood cells able to respond much faster and produce moreantibodies quicker to destroy the pathogens so the person doesn’tsuffer the symptoms of the disease.7. What is an antibiotic and what is it used for?Kills bacteria inside the body without harming human cells.

Infection and Response – AnswerIT8. Why is there a growing concern about bacterial resistance toantibiotics? The resistant bacteria are not killed and can continue tomultiply inside the body making the person very ill and infectingothers too.9. Which one of these statements is true?Painkillers are used to treat the symptoms of a disease and kill thepathogens which cause itPainkillers are used to kill the pathogens causing a diseasePainkillers are used to treat the symptoms of a disease but do not killthe pathogens.

LearnIT!KnowIT!Infectionand ResponsePart 2 Discovery of Drugs Development of Drugs Monoclonal Antibodies (Biology HT only)

Infection and Response part 2 – Discovery & drug developmentAspirin is a painkillerand antiinflammatory drug.This was first found inwillow bark.Traditionally drugswere extracted fromplants andmicro-organisms.videoFoxglove plants havebeen a source of thedrug digitalis whichacts on the heart.Alexander Flemingis famous fordiscoveringPenicillium mould.Fleming noticed thefungus on unwashedequipment and wenton to discover itsantibiotic properties.

Infection and Response part 2 – Development of drugsMost new drugs are developedand synthesised (made) in alaboratory by chemists in thepharmaceutical industry. Theinitial chemical may have beensourced from a plant.New drugs must be testedand trialled to check: Efficacy - that the drugswork Toxicity - that the drug isnot poisonous Dose - the most suitableamount to takePreclinical tests must becarried out before humansare allowed to take the drug.These preclinical tests aredone on cells, tissue samplesand live animals.

Infection and Response part 2 – Drug developmentIf successful the new drug will proceed to a clinical trial.The stages of a clinical trial are: Healthy volunteers try small doses of the drug to check it is safeStage 1 and has no side effects A small number of patients try the drug at a low dose to see if itStage 2 works A larger number of patients take the new drug and different dosesStage 3 are trialled to find the optimum dose A double blind trial will occur to see how effective the new drugStage 4 is. The patients are divided into groupsvideo

Infection and Response part 2 – Drug developmentA double blind trial is carried out on patients who have thedisease to make sure that it is actually the drug which is havingan effect on the patients and not anything else.The details of everyone taking part in the trial is entered into acomputer database. The computer groups people randomly.Each person receives a unique code and they receive themedicine which is labelled with the matching code.No-one knows who is receiving the real drug or a placebo untilthe end of the trial.The placebo is often the drug the patient was originally taking sothey still receive medical treatment.

Infection and Response part 2 – Monoclonal antibodies (Biology HT)Monoclonal antibodies are identical copies ofone type of antibody produced in a laboratory.How to produce monoclonal antibodies:1. A mouse is injected with a pathogen2. White blood cells called lymphocytesproduce antibodies3. Lymphocytes are removed from the mouseand fused with rapidly dividing mouse tumourcells4. The new cells are called hybridomas.5. The hybridomas divide rapidly and releaselots of antibodies which are then collected.Mono one

Infection and Response part 2 – Monoclonal antibodies (Biology HT)Monoclonal antibodies are specific to one binding site onthe antigen.This means that we can use monoclonal antibodies totarget a specific chemical or specific cells in the body.During pregnancy, a hormone called HCG is released intothe blood. Monoclonal antibodies can detect the presenceof this chemical at low levels and are used in pregnancytesting kits.

Infection and Response part 2 – Monoclonal antibodies (Biology HT)Monoclonal antibodies are also used in treating somecancers. The monoclonal antibodies are specific to the antigen onthe cancer cells. A chemical which stops cells dividing can be bound tothe monoclonal antibodies. The patient is given the monoclonal antibodies and theyattach to receptors on the cancer cells. The chemical stops the cancer cells growing and dividing.

Infection and Response part 2 – Monoclonal antibodies (Biology HT)Monoclonal antibody research has raised some concernsabout their ethical use.Mice are injected withpathogens and so theywill experience thedisease symptoms.Monoclonal antibodies have beensuccessful in treating some cancersand diabetes. But there have beendeaths when used to treat patientswith multiple sclerosis (MS).Mice provide antibodyproducing cells andtumour cells. Mice areinduced with cancer toget the tumour cells.Herceptin is used for breastcancer. It is not toxic and isspecific to breast cancer cellsso few side effects. But it iscostly.

QuestionIT!Infection and ResponsePart 2 Discovery of Drugs Development of Drugs Monoclonal Antibodies (Biology HT only)

Infection and Response – QuestionIT1. Choose the answer from the box to complete the sentences.Willow tree b

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