Science - Biology - Infection and Response - B3 Flashcards
what is a pathogen ?
pathogens are microorganisms that enter the body and cause disease. They cause communicable diseases.
what is a communicable disease ?
an infectious disease
what are the different types of pathogen ?
- bacteria
- viruses
- protists
- fungi
what is bacteria ?
very small cells which reproduce rapidly inside your body, they can make you feel ill by producing toxins which damage your cells and tissues
what is an example of bacteria ?
salmonella - food poisoning
what is a virus ?
viruses are not cells. They reproduce rapidly inside your body and live inside your cells and replicate themselves using the cells machinery which makes the cell usually burst releasing new viruses. The cell damage makes you feel ill
what is an example of a virus ?
HIV - infects and destroys cells that protect us against diseases
what is a protist ?
a pathogen transferred onto other organisms by a vector, which doesn’t get the disease itself
what is an example of a protist disease?
malaria is caused by a protist that lives inside a mosquito
what is fungi ?
a microorganism that can cause disease, and that produces spores that can be spread onto other organisms
what is an example of a fungi disease ?
rose black spot - black spot fungus infects rose plants
give 3 ways pathogens are spread
- water
- air
- direct contact
give an example of a pathogen that is caught through water
cholera - drinking dirty, contaminated water
give an example of a pathogen that is caught through air
influenza virus - spread in the air in droplets produced when a contaminated person coughs or sneezes
give an example of a pathogen that is caught through direct contact
athletes foot - fungus spread by touching the same things as an infected person
how is measles - a viral disease - spread ?
direct contact - droplets of someone’s cough or sneeze
what are the effects of measles ?
- red skin rash
- signs of fever
- high temperature
what can measles lead to if not treated ?
- pneumonia
- encephalitis - brain infection
how is measles prevented ?
vaccination
how is HIV spread ?
direct contact - sexual, exchanging bodily fluids, e.g blood
what are the symptoms of HIV ?
- first few weeks - flu like symptoms
- several years - potentially no symptoms
- aids - if body’s immune system is badly damaged and can’t cope with any diseases
how can HIV be controlled ?
- antiretroviral drugs - stops the virus replicating in the body
what is the tobacco mosaic virus ?
a virus that affects many species of plants
what are the effects of the tobacco mosaic virus?
- causes mosaic virus on the leaves
- leaves become discolored
- discoloration leads to less photosynthesis - effects growth
name 3 viral diseases ?
- measles
- HIV
- tobacco mosaic virus
what is the rose black spot ?
a fungus that causes purple or black spots to develop on the leaves of rose plants
what are the effects of the rose black spot disease ?
- leaves turn yellow and drop off
how is the rose black spot spread ?
through water or wind
how can the rose black spot be treated ?
- gardeners using fungicides by stripping the plant of its affected leaves
how is malaria caused ?
by a protist which uses a mosquito as a vector. when mosquitos feed on another animal it infects it by inserting the protist into the animals blood vessles
what are the effects of malaria ?
- repeating episodes of fever
how can malaria be prevented ?
- spraying exposed skin with insect repellent
- sleeping under a mosquito net
what are the effects of salmonella ?
- food poisoning
- fever
- stomach cramps
- vomiting
- diarrhoea
how is salmonella caught ?
- eating chicken that caught the disease whilst alive
- eating food that was contaminated by being prepared in unhygienic conditions
- eating raw chicken
how is salmonella prevented ?
- vaccinating chicken and turkey against salmonella
how is gonorrhea spread ?
direct contact - sexual transmitted disease
what are the effects of gonorrhea ?
- pain when they urinate
- thick yellow or green discharge from vagina or penis
how is gonorrhea prevented ?
- protected sex
- originally treated with penicillin but strains of bacteria have become resistant to this drug
how can you reduce and prevent the spread of disease ?
- being hygienic
- destroying vectors
- isolating infected individuals
- vaccination
what are the body’s non specific defence systems ?
- skin
- hairs and mucus
- trachea and bronchi
- stomach
how does the skin help defend the body ?
- acts as a barrier
- secretes antimicrobial substances which kills pathogens
how does hairs and mucus in your nose help defend the body ?
- trap particles that could contain pathogens
how do the trachea and bronchi help defend the body ?
- secretes mucus to help trap pathogens
- lined with cilia, which are hair-like structures which waft mucus up to the back of the throat where it can be swallowed
how does the stomach help defend the body ?
- produces hydrochloric acid which kills pathogens that make it far from the mouth
what are white blood cells ?
the most important part of your immune system
what do white blood cells do ?
travel around in your blood, crawling into every part of you, patrolling for microbes
what are the 3 things white blood cells could do when they come across a microbe ?
- consume them
- producing antitoxins
- producing antibodies
what is phagocytosis ?
the process where white blood cells engulf foreign cells and digest them to prevent disease
why do white blood cells produce antitoxins ?
to counteract toxins produced by invading bacteria
how do white blood cells produce antibodies ?
- every pathogen has an antigen on its surface
- when white blood cells come across a foreign antigen they produce proteins called antibodies
- these lock onto the invading cells so they can be found and destroyed by other white blood cells
what is an antigen ?
a molecule on the surface on a cell
why are different antibodies produced for every new antigen ?
they are specific to each antigen, as they won’t lock onto any others
what happens if a person is infected with the same pathogen again ?
white blood cells reproduce the antibodies to kill it, as your body is now naturally immune to that pathogen and won’t get ill
what do vaccinations do ?
prevent you from feeling ill
how to vaccinations work ?
where you inject small doses of dead or inactive pathogens which carry antigens so your white blood cells produce antibodies to attack them despite the pathogen being harmless, if the pathogen actually appears later down the line, the white blood cells can mass produce antibodies rapidly to kill of the pathogen so you don’t get ill
give an example of a common vaccination
MMR vaccine is given to children and contains weakened versions of viruses which cause measles, mumps and rubella
what are the advantages to vaccinations ?
- help control many infectious diseases
- big outbreaks of a disease called epidemics can be prevented if a large percentage of the population is vaccinated
what are the disadvantages of vaccinations ?
- they don’t always work
- sometimes you can have a bad reaction to vaccinations, e.g swelling, fever
what are painkillers ?
painkillers are drugs that relieve pain, but they don’t actually tackle the disease, they just reduce the symptoms
give an example of painkillers ?
aspirin
what are antibiotics ?
antibiotics kill or prevent the growth of the bacteria causing the problem without killing your own body cells - different antibiotics kill different types of bacteria
what can antibiotics not kill ?
viruses
why can’t antibiotics kill viruses ?
viruses reproduce using your own body cells so it is difficult to develop drugs that destroy only the virus without killing the body’s cells
what is antibiotic resistance ?
where bacteria mutates so it becomes resistant to an antibiotic
give an example of antibiotic resistant bacteria ?
some strains of bacteria that cause TB - lung disease- are resistant to several to several of the antibiotics that would normally be used to fight them
explain natural selection in bacteria
if you have an infection, some bacteria might be resistant to antibiotics, so when you treat the infection, only the non- resistant strain will be killed so the individual resistant bacteria will survive and reproduce, and its population will increase
how do you slow down the development of antibiotic resistance ?
- avoid over-prescribing antibiotics
- finish the whole course of antibiotics and don’t just stop once you feel better
where do drugs come from ?
- chemicals extracted plants
- extracted from microorganisms
give examples of drugs that were developed from chemicals extracted from plants
- aspirin - painkiller - chemical found in willow
- digitalis - treats heart conditions- found in foxgloves
give examples of of drugs that were extracted from microorganisms
penicillin
why do we do drug testing ?
to make sure that drugs are safe and effective
what are the 3 main stages in drug testing ?
- preclinical testing on human cells and tissues
- preclinical testing on live animals
- clinical testing on human volunteers
give the disadvantages of drug testing on human cells and tissues
you can’t use human cells and tissues to test drugs that affect whole or multiple body systems
why is there drug testing on live animals ?
- to test for efficacy - whether the drug works and produces produces the effect you’re looking for
- to find out about its toxicity - how harmful it is
- to find the right dosage
what is the law on Britain about animal testing ?
any new drugs must be tested on 2 different live mammals
in clinical trials, why is the drug first tested on healthy volunteers ?
to make sure that it works and doesn’t have any harmful side effects when the body is working normally
what is the optimum dose ?
the dose of drug which is the most effective and has few side effects
what is a placebo ?
a substance that is like the drug being tested but doesn’t do anything
why are placebos used ?
the doctor can see the actual difference that the drug makes - it allows for the placebo effect - patients are put into 2 different groups, 1 group is given the actual drug, the other group is given the placebo
what is the placebo effect ?
when the patient expects the treatment to work and so feels better even though the treatment isn’t doing anything
what are blind trials ?
when the patient doesn’t know whether they are getting the placebo or the actual drug
what are double blind trials ?
neither the patient nor the doctor knows who has the placebo
why are double blind trials used ?
so the doctors monitoring the patients aren’t subconsciously influenced by their knowledge
give an example where drug testing wasn’t used and something negative happened ?
Thalidomide was a sleeping pill that was only tested for that use, but was also found effective for relieving morning sickness in pregnant women. Because it wasn’t tested for morning sickness it caused abnormal limb development in the fetus. 10,000 babies were affected by thalidomide and only half survived
what are monoclonal antibodies
antibodies produced from lots of clones of a single white blood cell- a b lymphocyte- , which will only target one specific protein antigen
what is a B lymphocyte ?
a type of white blood cell
Because lymphocytes don’t divide easily, how are lots of clones made ?
tumor cells, which don’t divide easily but divide lots are grown very easily so are fused to a mouse b lymphocyte to create a hybridoma cell which can be cloned and produce antibodies
explain how monoclonal antibodies are made
- mouse is injected with chosen antigen
- b lymphocytes are taken from the mouse
- fast dividing tumor cells are fused with b lymphocyte
- this makes a hybridoma
- hybridoma cells divide quickly and produce the monoclonal antibodies
give an example of how monoclonal antibodies are used
in pregnancy tests
how do monoclonal antibodies work in pregnancy tests ?
- where you wee on in the stick has antibodies to the HGG hormone, a hormone found in only pregnant women’s urine , with blue beads attached
- the test strip - where it turns blue if pregnant- has some more antibodies to the hormone stuck onto it so they can’t move
what happens to the test stick if you’re pregnant?
- the HCG hormone binds to the antibodies on the blue beads and the urine moves up the stick carrying the hormone and the beads.
- the beads and hormone bind to the antibodies on the strip, so the blue beads get stuck on the strip, turning it blue
what happens to the test stick if you’re not pregnant ?
the urine move up the stick carrying the blue beads, but because the hormone isn’t there to stick the blue beads to the test strip it doesn’t go blue
what does the control window in pregnancy tests do ?
- it shows the person whether the test has worked correctly
- it has antibodies to the antibodies that were attached to the blue beads
- when the beads reach the control window the antibodies attached to them will bind to the antibodies stuck to the control window
- which should go blue when the test is positive or negative to ensure the test is working
how does a monoclonal antibody help treat cancer ?
- monoclonal antibody is attached to an anti- cancer drug
- antibody binds to tumor markers on cancer cell to make monoclonal antibody
what is a tumor marker ?
antigens on cancer cells on the cell membrane that aren’t found on normal body cells
give an example of monoclonal antibodies which are used to bind to hormones and other chemicals in blood to measure their levels ?
- ELISA test is used to detect banned drugs in athletes’ urine
how are monoclonal antibodies used in research?
- monoclonal antibodies help locate specific molecules on a cell or tissue
- They bind to the specific molecule you’re looking for
- the antibodies are then bound to a florescent dye
- if the molecules are present in the sample you’re analyzing, the monoclonal antibodies will attach to them
- they can be detected with the dye
what are the advantages to monoclonal antibodies ?
- cancer treatment
- side effects of antibody based drug are lower than for standard chemotherapy or radiotherapy
what are the disadvantages to monoclonal antibodies ?
- they have more side effects than originally expected
- not as widely used as anticipated
name different types of plant diseases ?
- deficiency disease
- diseases caused by pathogens
- infestation with pests
what’s a deficiency disease ?
plants need mineral ions from the soil, if there aren’t enough plants suffer deficiency symptoms
give an example of a deficiency disease ?
nitrates are needed to make proteins and for growth. A lack of nitrate causes stunted growth
what is plant infestation with pests ?
where plants are damaged by insects
give an example of infestation with pests ?
aphids are an insect that causes a huge damage to plants
how do you detect a plant disease ?
- stunted growth
- spots on the leaves
- patches of decay (rot)
- abnormal growths
- malformed stems or leaves
- discoloration
how do you identify plant diseases ?
- looking up signs in a gardening manual
- taking the infected plant to a lab
- using test kits that identify the pathogen
what are the 3 types of defences plants have ?
- physical
- chemical
- mechanical
give plant physical defences
- most plant leaves and stems have waxy cuticles which provides a barrier to stop pathogens entering
- plant cells have cell walls made from cellulose to form a physical barrier from pathogens
- plants have layers of dead cells around their stems, e.g bark which creates a barrier
give plant chemical defences
- some plants can produce antibacterial chemicals which kill bacteria, e.g witch hazel
- some plants produce poisons which deter herbivores, e.g tobacco plants
give plant mechanical defences
- some plants have adapted thorns and hairs to stop animals eating them
- other plants have leaves that droop or curl when something touches them to prevent themselves from being eaten
- some plants mimic other organisms e.g, passion flower has bright yellow spots on its leaves which look like butterfly eggs which stops butterflies laying their eggs there
