Infection & response topic 3 biology

What are pathogens, what do they cause, what can they infect?

What are pathogens, what do they cause, what can they infect?

1. Pathogens are microorganisms that enter body & cause disease

2. Cause communicable (infectious) diseases , can be easily spread

3. both plants & animals can be infected by pathogens

How do bacteria make you feel, why & how can they do this?

1. Really small cells (1/100 size of body cells) can reproduce rapidly inside body

2. Make you feel ill → producing toxins (poisons) that damage cells & tissues

Why are viruses not cells? (live, size, reproduce, feel ill)

1. Aren’t cells → tiny about 1/100 size of bacterium

2. Can reproduce rapidly inside body

3. live inside cells & replicate using cells’ machinery to produce copies of themselves, cell usually bursts releasing all new viruses

4. cell damage make you feel ill

Protists are unicellular eukaryotes (parasites, vectors)

1. all eukaryotes & most are unicellular

2. Some are protists, live on/ inside organisms & cause damage. Often transferred to organism by vector (doesn’t get disease itself - insect carries protist)

What do fungi have? (unicellular, disease, spores)

1. some are unicellular, others have body made up of hyphae (thread-like structures)

2. Hyphae grow & penetrate human skin & surface of plants causing disease

3. Hyphae produce spores → spread to other plants & animals

How can pathogens be spread? (3 points & examples)

1. Water → by drinking/ bathing in dirty water → bacterial infection, by drinking water contaminated with diarrhoea of other suffers

2. Air → carried in air & breathed in → airborne pathogens carried in air in droplets (produced when cough/sneeze) → influenza virus causes flu spread this way

3. Direct contact →touching contaminated surfaces including skin → athlete’s foot makes skin itch & flake off, spread touching same things as infected person (shower floors, towels)

Measles is a viral disease (spread, symptoms, results, prevention)

1. spread by droplets from infected persons sneeze/ cough,

2. Develop red skin rash & show signs of fever

3. Can be serious/ fatal, if complications. Can lead to pneumonia/ inflammation of brain (encephalitis)

4. Most are vaccinated against it when young

HIV is a viral viral disease (spread, symptoms, control, does, damage)

1. spread by sexual contact/ exchanging bodily fluids (blood), can happen when sharing needles when taking drugs

2. Causes flu-like symptoms for weeks, usually don’t experience symptoms for years → HIV can be controlled with antiretroviral drugs, stop virus replicating

3. Virus attacks immune cells

4. Body’s immune system badly damaged → cant cope with other infections/ cancers → virus known as late stage HIV infection/ AIDS

Tobacco mosaic virus (TMV) is a viral disease (affects, causes, means)

1. affects many species plants (tomatoes)

2. causes mosaic pattern on leaves of plants → become discoloured

3. Discolouration means plants cant carry out photosynthesis as well→ affects growth

Fungal disease (example, cause, means, spreads. treat)

1. Rose black spot (fungus) → causes purple/ black spots develop on leaves of rose plants → leaves turn yellow & drop off

2. Less photosynthesis → plant doesn’t grow very well

3. Spreads through environment (water/ wind)

4. Treat using fungicides & stripping plant of affected leaves → need to be destroyed so fungus cant spread

Disease caused by a protist (cycle, vector, spread, symptoms, reduce, protect)

1. Malaria → protist’s life cycle take place inside mosquito (vectors), pick up malaria protist when feed on infected animal

2. Every time mosquito feeds on other animal → infects by inserting protist into blood vessels

3. Cause repeating episodes of fever, can be fatal

4. Reduce spread → stopping mosquitos from breeding

5. Protected from mosquitoes using insecticides & mosquito nets

salmonella is a type of bacterial disease (cause, suffer, symptoms cause, catch &example, prevention spread)

1. causes food poisoning

2. suffer from fever, stomach cramps, vomiting & diarrhoea

3. symptoms caused by toxins bacteria produce

4. get salmonella by eating food contaminated with salmonella bacteria (eating chicken caught disease whilst alive/ eating food contaminated by being prepared unhygienic way)

5. In UK most poultry (chicken & Turkeys) given vaccination against salmonella → controls spread of disease

Gonorrhoea is type of bacterial disease (STD, caused, symptoms, og treated why, prevention)

1. STD’s transmitted sexual contact (unprotected sex)

2. caused by bacteria

3. symptoms → pai when urinating, thick yellow/ green discharge from vagina/ penis

4. originally treated with penicillin (antibiotic), strains of bacteria became resistant to it

5. Prevent spread of gonorrhoea → treated with antibiotics & use barrier methods of contraception

How can spread of disease be reduced/ prevented (4 points)

1. Hygienic → simple hygiene measures → washing hands before preparing food/ after sneezed

2. Destroying vectors → insects can be killed using insecticides/ by destroying habitat (no longer breed)

3. Isolating infected individuals → isolate someone with communicable disease → prevent passing it on

4. Vaccination (communicable disease)→ less likely develop infection & pass it on

Body’s defence system features stop pathogens/ bacteria getting in (5 points)

1. skin (barrier) to pathogens & secretes antimicrobial substances (kill pathogens)

2. hair & mucus in nose trap particles that could contain pathogens

3. trachea & bronchi (breathing pipework) secrete mucus to trap pathogens.

4. Lined with cilia (hair-like structures) waft mucus up back of throat where can be swallowed

5. Stomach produces hydrochloric acid (kills pathogens make it far from mouth)

Immune system can attack pathogens (immune system, microbes, attack)

1. pathogens make it into body → immune system destroy them

2. Most important part of immune system → white blood cells → travel around blood & crawl into every part body, constantly patrolling for microbes → come across invading microbes have 3 lines of attack

3 lines of attack when white blood cells come across invading microbes

1. phagocytosis → engulf foreign cells & digest them

2. Producing antibodies → invading pathogens have antigens on surface → WBC find & produce proteins (antibodies - specific antigens) lock onto invading cells (find & destroy),antibodies produced rapidly & carried in blood to find similar bacteria & viruses, remember pathogen (rapidly produce antibodies to kill → immune to pathogen)

3. Producing antitoxins → counteract toxins produced by invading bacteria

How can vaccination protect from future infections (learn, what & example, after)

1. infected with new pathogen, takes white blood cells time to learn how deal with it (by that time can get ill)

2. Vaccinations usually involve injecting small amounts of dead/ inactive pathogens → carry antigens which cause body to produce antibodies (attack them) → even though pathogen is harmless (dead/inactive) → example, MMR vaccine contains weakened versions virus that causes measles, mumps. rubella (German measles) in one vaccine

3. If pathogens of same type appear after → white blood cells rapidly mass-produce antibodies to kill pathogen

Pros of vaccination (2 points, example, outbreak)

1. helped control lots communicable diseases, were once common (polio, measles, whooping cough, mumps, rubella, tetanus) → small pox doesn’t occurs at all & polio infections fallen by 99%

2. epidemics (big outbreak of disease) prevented if large percentage population is vaccinated → people who aren’t vaccinated unlikely catch disease (fewer people able pass it on). Significant number people who aren’t vaccinated → disease can spread quickly through them & lots peope ill at same time

Cons of vaccination

1. don’t always work → don’t give immunity

2. Can have bad reaction to vaccine (swelling or something more serious like fever/ seizures), but are very rare

What drugs relieve symptoms (relieve, don’t) & which cure problem (name, role, don’t, reduced)

Relieve symptoms

1. painkillers (aspirin) relieve pain, don’t tackle cause of disease/ kill pathogens, help reduce symptoms

2. Lots cold remedies don’t actually cure colds

Cure problem

1. antibiotics (penicillin actually kill/ prevent growth of bacteria causing problem without killing own body cells, different antibiotics kill different types of bacteria → important treated with right one

2. Antibiotics don’t destroy virus (flu/ cord viruses), viruses reproduce using body cells → very difficult to develop drugs that destroy just virus without killing body cells

3. Use of antibiotics greatly reduced number deaths from communicable diseases caused by bacteria

How can bacteria become resistant to antibiotics (mutate, infection, treat, individual, serious & example, slowdown rate, course)

1. bacteria mutate (sometimes cause them to be resistant/ not killed by antibiotic)

2. Infection → some bacteria antibiotic resistant

3. Treat infection→ only non-resistant strains bacteria killed

4. individual resistant survive & reproduce → population increases (natural selection)

5. restrain strain cause serious infection , MRSA (meticillin-resistant-staphylococcus aureus) causes serious wound infections & resistant to powerful antibiotic meticillin

6. Slow down rate development resistant trains → doctors avoid over-prescribing antibiotics (wont get them for sore throat, only something serious)

7. Important Finish whole course antibiotics & don’t stop once feel better

Drugs extracted from plants (2 points, produce, chemicals & 2 examples)

1. plants produce variety chemicals to defend themselves against pests & pathogens

2. some chemicals used as drugs to treat human disease/ relieve symptoms. Current medicine discovered by studying plants used traditional cures:

   • Aspirin (painkiller & lowers fever, developed from chemical found in willow)

   • Digitalis (treat heart conditions, developed chemical found in foxgloves)

Drugs extracted from microorganisms (Fleming, penicillin, today)

• Alexander Fleming clearing out petri dishes containing bacteria, noticed one had mould on it & area around mould was bacteria free

• Found mould (penicillium notatum) on petri dish was producing substance that killed bacteria → penicillin)

  (these days drugs made large scale in pharmaceutical industry - produced by chemists in lab , process might start with chemical extracted from plant)

3 main stages in drug testing

1. Preclinical testing, → human cells & tissues,

2. Preclinical testing → living animals test (efficacy, toxicity, dosage)

3. Clinical trials → human volunteers, healthy volunteers → sufferers of disease

Preclinical testing (1 drug testing) (can’t, example)

1. tested on human cells & tissues in lab,

2. cant use human cells & tissues to test drugs affect whole/ multiple body systems (testing drug for blood pressure must be done on whole animal because has intact circulatory system)

Preclinical testing (2 drug testing) (law, thoughts)

1. test drug on live animals, to test for efficacy (whether works & produces effect looking for), toxicity (how harmful) & best dosage (concentration should be given & how often)

2. Law in britain → any new drug must be tested on 2 different live mammals → some think cruel test on animals but others think safest way make sure drug isn’t dangerous

Clinical trials (3 drug testing) (6 points, healthy, suffering, how well, blind, results)

1. tested on healthy volunteers, make sure no harmful side effects when body working normally. Start trial = very low dose & gradually increased

2. tested on people suffering from illness, optimum dose found (most effective & few side effects)

3. test how well works → patients randomly put 2 groups, 1 given new drug & other placebo. Doctor can see actual difference drug makes → allows place effect

4. Are blind → patient doesn’t know whether getting placebo/ drug, often double blind → neither patient nor doctor know until results gathered. Doctor monitoring patients & analysing results aren’t subconsciously influenced

5. Results aren’t published until they’ve been through peer review → helps prevent false claims

how are Monoclonal antibodies are identical antibodies (Antibodies, monoclonal, divide, tumour, fuse, cloned, bind)

1. antibodies → produced B-lymphocytes (type white blood cell)

2. Monoclonal antibodies → produced lots clones of single white blood cell → all antibodies identical & will target 1 specific protein antigen

3. Lymphocytes don’t divide easily

4. Tumour cells → don’t produce antibodies but divide lots → grown really easily

5. Possible fuse mouse B-lymphocyte with tomour cell → hybridoma cell

6. Hybridoma cells → cloned to get lots identical cells → produce same antibodies (monoclonal) → can be collected & purified

7. Can make monoclonal antibodies bind to anything → antigen only found on surface of 1 type cell → MA really useful because only bind to (target) that molecule → use target specific cell/ chemical in body

How are Monoclonal antibodies used in pregnancy test (HCG, pee, antibodies, pregnant, not)

Hormone HCG found in urine of pregnant women, pregnancy testing sticks detect HCG (hormone):

1. bit of stick pee on has some antibodies to hormone, with blue beads attached

2. Test strip (turns blue if pregnant) has some more antibodies to hormone stuck onto it (cant move)

3. If pregnant & wee on stick → hormone bins to antibodies on blue beads → urine moves up stick carrying hormone & beads → beads & hormone bind to antibodies on strip → blue beads get stuck on strip turning it blue

4. If not pregnant & wee on stick → urine moves up stick carrying blue beads →but nothing to stick blue beads onto test strip → doesn’t go blue

How can monoclonal antibodies be used to treat diseases (different, tumour markers, drug, patient, kills)

1. different cells = different antigens on cell surface, make monoclonal antibodies bind to specific cells (just liver cells)

2. Cancer cells → have antigens on cell membrane that aren’t found normal body cells → tumour markers

3. Anti-cancer drug → attached to those monoclonal antibodies → might be radioactive substance, toxic drug/ chemical which stops cancer cells growing & dividing

4. Antibodies given to patient through drip → target specific cells (cancer cells), only bind to tumour markers

5. drug kills cancer cells but doesn’t kill normal body cells near tumour

monoclonal abilities can be used to: (measure, test, locate: bind, dye, attach)

1. bind to hormones & other chemicals in blood to measure their levels

2. test blood samples in labs for certain pathogens

3. Locate specific molecules on cell or in tissue:

   1. Monoclonal antibodies made that bind to specific molecule looking for

   2. antibodies bound to fluorescent dye

   3. if molecules present in sample → monoclonal antibodies attach to them & can be detected using dye

problems of monoclonal antibodies (treatments, side effects, widely)

1. other cancer treatments (standard chemotherapy & radiotherapy) can affect normal body cells whilst killing cancer cells, whereas monoclonal antibodies target specific cells → side effects of antiboy-based drug lower than chemotherapy/ radiotherapy

2. Monoclonal antibodies cause more side effects than originally expected → cause fever, vomiting, low blood pressure → when first developed scientists though because target specific cell/ molecule would create lots side effects

3. Not as widely used as treatments as scientists had originally thought

Plants need mineral ions if there aren’t enough, plants suffer deficiency symptoms (growth, photosynthesis)

1. nitrates needed to make protein & therefore growth → lack causes stunted growth

2. Magnesium ions needed making chlorophyll which needed for photosynthesis → lack causes plants suffer from chlorosis & have yellow leaves

Plants can be infected by viral, bacterial & fungal pathogens, can also be infested & damaged by insects (aphids are insect that can cause huge damage to plants)

(symptoms, infestations, different diseases: searching, identify, testing)

1. common symptoms of disease → stunted growth, spots on leaves, patches of decay (rot), abnormal growths (lumps), malformed stems/ leaves, discolouration

2. Infestations of pests easy to spot → able to see them on plants

3. Different plant diseases have different signs, identified by:
   1. looking up signs in gardening manual/ gardening website

   2. taking infected plant to lab, scientists can identify pathogen

   3. using testing kits that identify pathogen using monoclonal antibodies

Physical defences of plants (barrier, physical, bark)

1. leaves & stems have waxy cuticle → provides barrier to stop pathogens entering

2. Plant cells surrounded by cell wall made of cellulose → form physical barrier against pathogens that make it past waxy cuticle

3. Layers of dead cells around stems → example, outer part of bark on trees → acts as barrier to stop pathogens entering

Chemical defences of plants ( antibacterial, poisons)

1. some produce antibacterial chemical which kill bacteria → mint plant & witch hazel

2. Others produce poisons which deter herbivores → tobacco plants, foxgloves, deadly nightshade

Mechanical defences of plants ( stop, knocking, mimic)

1. thorns & hairs → stop animals touching & eating them

2. Leaves that droop/curl when something touches them → prevent themselves being eaten by knocking insects off themselves & moving away from things

3. Mimic other organisms → passion flower has bright yellow spots on leaves which look like butterfly eggs → stops other butterflies laying eggs there. Several species of plant in ‘ice plant family’ in southern Africa look likes tones & pebbles → tricks other organisms into not eating them