infection and response

describe how viruses make people ill

• very small

• move into cells and use the biochemistry of it to make many copies of itself

• this leads to the cell bursting and releasing all of the copies into the blood stream

• the damage and destruction of the cell makes the individual feel ill

describe how bacteria make people ill

• small

• multiply very quickly through dividing by a process called binary fission

• produce toxins that can damage cells

describe how protists make people ill

• some and parasitic meaning they use humans and animals as their hosts ( live on and inside causing damage)

describe how fungi makes people ill

• produce spores which can be spread to other organisms

what is a fungus

can be either single-called or have a body made of hyphae (threadlike structures)

3 ways disease can be spread

• direct contact

• by water

• by air

how can direct contact spread disease + examples

touching contaminated surfaces eg kissing, contact with bodily fluids, microorganisms left from faeces

how can water spread disease

drinking or coming into contact with dirty water

how can air spread disease + examples

pathogens can be carried in the air and then breathed in for example droplet infection where when sneezing, coughing, talking expels pathogens in droplets which can be breathed in

how to limit the spread of disease (pathogens)

• improve hygiene

• reduce contact with infected people

• remove vectors

• vaccination

name 3 viral diseases

• tobacco mosaic virus

• HIV

• Measles

symptoms of measles

fever and red skin rash, can lead to other problems like pneumonia (lung infection), encephalitis (brain infection) and blindness

how is measles spread

droplet infection

how is measles prevented

vaccinations for young children to reduce transmission

symptoms of HIV

initially flu-like symptoms, then virus attacks the immune system and leads to AIDS

how is HIV spread

by sexual contact or exchange of bodily fluids such as blood

how is HIV prevented

• the spread - using confond, not sharing a needles, screening blood when ins used in transfusions, mothers with HIV bottle-feeding their children

• the development into AIDS - use of antiretroviral drugs to stop the virus replicating in the body

what plant goes tobacco mosaic virus commonly affect

tomato plant

symptoms of tobacco mosaic virus

discolouration of the leaves, affected part of leaf cant photosynthesise resulting in a reduction of the yield

how is tobacco mosaic virus spread

contact between diseased plants and healthy plants insects act as vectors

how to prevent tobacco mosaic virus

good field hygiene, pest control, growing TMV- resistant strains

why are bacterial diseases on the rise

becoming resistant to antibiotics

what is salmonella food poisoning

bacteria that live in the gut of different animal which we ingest when we eat meat

symptoms of salmonella

• stomach cramps

• vomiting

• diarrhoea

• fever

all caused by the toxins they secrete

how is salmonella spread

bacteria found in raw meat and eggs, unhygienic conditions

preventing salmonella

poultry are vaccinated against salmonella, keeping raw meat away from cooked food, wash hands and surfaces when handling it, cook food thoroughly

symptoms of gonorrhoea

• thick yellow or green discharge from the vagina or penis, pain when urinating

how is gonorrhoea spread

STD spread through unprotected sexual contact

prevention of gonorrhoea

by using contraception such as condoms and antibiotics (used to be treated with penicillin but many restraint strains are developing)

name a fungal disease

rose black spot

symptoms of rose black spot

purple or black spots on leaves of rose plants, reduces the area ir the leaf available for photosynthesis leaves turn yellow and drop early

how is rose black spot spread

the spores of the fungus are spread in water or by wind

how is rose black spot prevented

by using fungicides or stripping plant of affected leaves and burning them

name a protist disease

malaria

what is malaria

caused by protists pathogens that enter red blood cells and damage them

symptoms of malaria

fevers and shaking (when the protists bursts out of blood cells)

how is malaria spread

the vector is the female anopheles mosquito in which the protists reproduce sexually. When the mosquito punctures the skin to feed on blood the protists enter the human bloodstream via their saliva

what does the non-specific defence system do

prevents pathogens from entering the body

4 elements of non-specific defence system

• skin

• nose

• trachea + bronchi

• stomach

how does the skin benefit the non-specific defence system

• physical barrier

• produces anti microbial secretions to kill pathogens

• good microorganisms known as skin flora compete with bad ones for space and nutrients

how does the nose benefit the non-specific defence system

• has hairs and mucus which prevent particles from entering your lungs

how does the trachea and bronchi benefit the non-specific defence system

• secrete mucus in order to trap pathogens

• cilia (hair like structures of cells) beat to waft mucus upwards to be swallowed

how does the stomach benefit the non-specific defence system

produces hydrochloride acid that kills any pathogens in your mucus, food , drink

what’s the role of the specific immune system

acts to destroy any pathogens whoch pass through the non-specific immune system to the body

what 3 different ways can white blood cells act

• phagocytosis

• producing antibodies

• producing antitoxins

how does the step of phagocytosis in the specific immune system help to protect you?

• engulfing and consuming pathogens

• this destroys them meaning they can no longer make you feel ill

how does the step of producibg antibodies in the specific immune system help to protect you?

each pathogen has an antigen on their surface which is a structure which a specific complementary antibody can bind to, once the antibodies bind to the pathogen the pathogens start to clump together making it easier for them to be found by white blood cells

what happens when you become infected again with the same pathogen?

the specific complementary antibodies will be produced at a faster rate - the individual will not feel the symptoms of the illness they are said to be immune

how does the step of producing antitoxins in the specific immune system help to protect you?

they neutralise the toxins released by the pathogen by binding to them

what do vaccines do

making an individual immune to a certain disease they’re protected against it before they’re been affected

what is herd immunity

immunising a large proportion of the population, limits the spread as there are less people to catch the disease from

how do vaccines work

• they contain a dead or inactivated form of the pathogen

• this stimulates white blood cells to produce antibodies complementary to the antigens on the pathogen

• this replicates the first infection of a disease just with no symptoms

2 advantages of vaccines

• eradicated many diseases (smallpox) and reduced the occurrence of many (rubella)

• epidemics can be prevented through herd immunity

2 disadvantages of a vaccine

• not always effective in providing immunity

• bad reactions (fevers) can occur in response to vaccines

what are antibiotics

medicines that kill bacterial pathogens inside the body, without damaging body cells, they cannot kill viruses as they use body cells to reproduce, meaning any drugs that target them would affect body tissue too

what do painkillers do

treat symptoms don’t stop the disease

how can antibiotics be taken

• pills

• syrup

• directly into blood stream

example of an antibiotic

penicillin

explain how bacteria becomes resistant to an antibiotic

• mutations can occur during reproduction resulting in certain bacteria bon longer being killed by antibiotics

• when bacteria is exposed to antibiotics only the non-resistant ones die

• the resistant bacteria survive and reproduce meaning the population of resistant bacteria increases

how to prevent the development of resistant strains

• stop overusing antibiotics

• finishing courses of antibiotics to kill all of the bacteria

how are drugs tested

preclinical testing and clinical trials

how are the chemicals that plants use to kill pests and pathogens helpful with an example

can treat symptoms of human diseases

aspirin is used as a painkiller and it originates from willow

how was penicillin made

Fleming was growing bacteria on plates he found moult in his culture plates, with clear rings around the mould indicate oh there was no longer any bacteria there, he found the mould was producing a substance called penicillin which killer bacteria

what is clinical testing

uses volunteers and patients

how does clinical testing work

• first tested in healthy volunteers with low dose to ensure no harmful side effects

• tested on patients to find most effective dose

• half the patients get a placebo half get the actual one to observe the effect of the drug

• can be single/double blind

• then are peer reviewed