Infection And Response Flashcards
What is a communicable disease?
A disease that is caused by a pathogen which can be spread from person to person
What is a pathogen?
disease causing microorganism
How do bacteria cause disease?
Once inside the body, they divide rapidly by binary fission. They kill cells and produce harmful toxins.
How do viruses cause disease?
They invade and reproduce inside living body cells, leading to cell damage.
Give three ways in which pathogens can be spread?
● By air - flu, tuberculosis and the common cold are spread by droplet infection.
● By water - fungal spores in water spread plant diseases.
● By direct contact - common in plant diseases and sexually transmitted infections.
Give four ways in which the spread of pathogens can be reduced
● Hygiene - handwashing, disinfectants, tissues.
● Reducing contact with infected individuals - quarantine.
● Removing vectors - use of pesticides and insecticides, removal of habitats.
● Vaccination.
Why is it especially important to prevent the spread of viral diseases?
Scientists have not yet developed cures for many viral diseases.
What is measles?
Measles is a serious viral disease that can cause blindness and brain damage. The main symptoms are a fever and a red skin rash.
How is measles spread?
By air - through the inhalation of droplets from coughs and sneezes.
What is HIV/AIDS?
HIV is a virus which attacks and damages the immune system until it can no longer function properly. AIDS is the condition resulting from a long-term HIV infection. There is no cure or vaccine for HIV/AIDS.
How is HIV spread?
Direct sexual contact and the exchange of bodily fluids eg. blood, breastmilk.
How can the spread of HIV/AIDS be prevented?
● Use of condoms
● Screening of blood for transfusions
● Not sharing needles
● Bottle-feeding by HIV-positive mothers
● Use of antiretroviral drugs to prevent the development of AIDS
What is tobacco mosaic virus?
A plant pathogen which causes leaf discolouration when cells are damaged. Affected areas cannot photosynthesise, reducing the crop yield. As there is no treatment, farmers grow TMV-resistant crop strains to avoid infection.
How is tobacco mosaic virus spread?
Contact between infected and healthy plants. Insects may act as vectors which transfer the virus between different plants.
What is salmonella?
A type of bacteria found in raw meat, poultry and eggs. If they enter the body via food poisoning, they can affect natural gut bacteria.
What are the symptoms of salmonella food poisoning?
● Fever
● Abdominal cramping
● Vomiting
● Diarrhoea
May be fatal in very young or elderly populations due the risk of dehydration.
How can the spread of salmonella be limited?
● Vaccinating animals intended for consumption
● Keep raw meat away from cooked meat
● Disinfect hands and surfaces after contact with raw meat
● Thoroughly cook meat
What is gonorrhoea?
A sexually transmitted bacterial infection caused by unprotected sex with an infected individual. Early symptoms include yellow/green discharge from genitals and painful urination, although it may be symptomless. Its spread can be controlled through the use of antibiotics (no longer penicillin as many strains are resistant) and using condoms.
What is rose black spot?
A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early.
How is rose black spot fungus spread?
Fungal spores spread by wind and water
How can the rose black spot fungus be treated?
● Using fungicides
● Destroying infected leaves
What is malaria?
Malaria is a disease caused by protist pathogens. The disease is carried from host to host by mosquitoes, and the protists enter the human bloodstream when they feed. Symptoms include fever and shaking, and it may also be fatal in some cases.
How can the spread of malaria be reduced?
● Using insecticides
● Using insect nets to avoid bites
● Prevent mosquito breeding by removing stagnant water
● Antimalarial drugs
How does the skin prevent pathogens from entering the body?
● Acts as a physical barrier.
● Scab formation after skin is cut/wounded.
● Antimicrobial secretions which can kill pathogens.
● Healthy skin flora compete with pathogens and act as an additional barrier.
How do the respiratory systems prevent pathogens from entering the body?
Nose - has hairs and mucus which trap pathogens
Trachea and bronchi - have mucus that traps pathogens. Ciliates cells move mucus to the mouth so it can be swallowed
How does the stomach prevent pathogens infecting the body?
● Secretes hydrochloric acid - kills any pathogens present.
How does phagocytosis protect us against disease?
White blood cells (phagocytes) ingest and destroy pathogens so they cannot infect more cells.
How does antibody production protect us against disease?
White blood cells produce antibodies which are complementary to a specific antigen on a pathogen. The binding of antibodies to antigens causes pathogens to clump together, making them easier to destroy. In the case of a second infection, the correct antibodies can be produced rapidly, preventing the person getting the same disease again.
How does antitoxin production protect us against disease?
Antitoxins bind to toxins released by pathogens and neutralise them.
What is a vaccination?
Contains a dead or inactivated form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen. In the case of a second infection, memory cells can rapidly produce the correct antibodies and prevent illness.
What is herd immunity?
If a sufficiently high proportion of a population are immune to a disease (especially through vaccination), the spread of this disease will be limited.
What are the advantages of vaccinations?
● They have eradicated many deadly diseases eg. smallpox.
● Many epidemics can be prevented by vaccinations.
● Herd immunity protects those who cannot have vaccination
What are the disadvantages of vaccinations?
● Not guaranteed to work - might not protect against multiple strains of a pathogen.
● May be side effects or adverse reactions.
What drugs are used to cure some bacterial diseases?
Antibiotics - they can kill bacterial pathogens inside the body.
How do antibiotics work?
Antibiotics kill bacterial pathogens inside the body, but do not kill human cells. Whilst some antibiotics kill a wide range of bacteria, it is important that the right antibiotic is used for specific bacteria.
Why can antibiotics not be used to treat viruses?
Antibiotics have no effect on viral pathogens as they live inside the host’s (human) cells. Therefore, it is difficult to design drugs that would kill the virus and not destroy human cells at the same time.
What is antibiotic resistance?
Antibiotic resistance occurs when mutations lead to individual bacteria being resistant to an antibiotic. These bacteria are able to survive, reproduce and pass on their alleles, leading to a greater proportion of antibiotic-resistant bacteria. This is concerning as some types of bacteria are becoming resistant to all known antibiotics, so the diseases that they cause cannot be cured.
How can we prevent antibiotic resistance?
● Avoid overuse and unnecessary use of antibiotics - eg. antibiotics are often used for viral infections.
● Finish antibiotic courses - to ensure all bacteria is killed.
What effect do painkillers have on infectious diseases?
Painkillers can only treat the symptoms but do not kill pathogens.
What plant is the heart drug digitalis extracted from?
Foxgloves
What painkiller originates from a compound found in willow bark?
aspirin
What antibiotic was discovered by Alexander Fleming from a type of mould?
penicillin
What are the four qualities of a good medicine?
● Effective
● Safe
● Stable
● Able to be taken in and removed easily
What three main factors are tested for when developing new drugs?
Toxicity, efficacy and dose
How is preclinical testing carried out?
In a laboratory - uses cells, tissues and live animals
How is clinical testing carried out?
Uses healthy volunteers and patients. Firstly, the drug is tested at a low dose on healthy people - then tested on patients and on a larger scale to find the optimum dose. Often, one group receive a placebo (not the test drug) and the other group receive the actual drug, in order to assess its efficacy.
What is the difference between a single-blind and a double-blind trial?
In a single-blind trial, only the doctor knows whether the patient is receiving the drug or the placebo. In a double-blind trial, neither the patient nor the doctor knows. Double-blind trials help remove bias on the part of the doctor.
What is a peer review?
Where the results of drug trials are checked over by scientists knowledgeable in this field.
What are monoclonal antibodies?
● Antibodies that are clones from one parent cell
● Specific to one type of antigen
Describe how monoclonal antibodies are produced
- Specific antigen injected into an animal (e.g. mouse).
- B-lymphocytes producing complementary antibodies extracted.
- B-lymphocytes fuse with myeloma cells to form hybridoma cells - these cells can divide and produce antibody.
- Hybridoma cells cultured.
- Monoclonal antibodies collected and purified.
Outline the use of monoclonal antibodies
Detection of pathogens
Location of cancer cells and blood clots
Treatment of cancer
Used in pregnancy test kits
What are myeloma cells?
Type of tumour cell
What do pregnancy kits test for?
hCG in urine
What does a pregnancy test consist of?
A stick containing monoclonal antibodies (mAbs) specific to hCG:
● mAbs attached to a blue bead (free to move)
● mAbs fixed to the test stick
Describe what happens to test stick if a women is pregnant
-hCG in urine binds to monoclonal antibodies attached to a blue bead.
-Monoclonal antibodies with hCG diffuse up dipstick.
-Blue line forms
Describe what happens to the test stick of a women is not pregnant
No hCG in urine so a blue line isn’t formed
What is the advantages of using monoclonal antibodies to test for pathogens?
● Specific to one particular antigen
● Very accurate
● Quick results
Why can monoclonal antibodies be used to target cancer cells?
● Cancer cells have specific antigens called ‘tumour markers’ on their membranes.
● mAbs are specific to one type of antigen so can be targeted to ‘tumour markers’ without damaging other cells.
Describe how monoclonal antibodies can be used to diagnose cancer
● mAbs tagged to a radioactive substance.
● mAbs injected into the patient’s bloodstream.
● mAbs bind to ‘tumour markers’ on cancer cells.
● Emitted radiation is detected using a specialised scanner enabling doctors to determine the location of cancer cells.
How can monoclonal antibodies be used to target drugs to cancer cells?
● mAbs attached to an anti-cancer drug.
● mAbs injected into the patient’s bloodstream.
● mAbs bind to ‘tumour markers’ on cancer cells.
● Anti-cancer drug destroys cancer cells.
Why are cancer treatments that use monoclonal antibodies favoured over traditional treatments?
● Radiotherapy and chemotherapy target rapidly dividing cells.
● Healthy cells are damaged as a consequence, producing unpleasant side effects.
● mAbs only target cancer cells, reducing damage to normal cells.
How can monoclonal antibodies be used to locate blood clots?
● mAbs tagged to a radioactive substance.
● mAbs target and bind to specific proteins in blood clots.
● Radiation emitted by mAbs is detected, enabling the location of blood clots to be identified.
How do aphids cause damage to plants?
They use their sharp mouthparts to extract sap from the plant phloem, weakening the plant. They are also vectors who can transfer pathogens from diseased plants to healthy plants.
How can we reduce the number of aphids?
● Chemical pesticides
● Biological pest control - using ladybirds
Why do plants need a good supply of nitrate ions?
Nitrate ions are required to convert sugars into proteins which are required for the plant to grow. As a result, the growth of the plant will be stunted if there is not an adequate supply of nitrates.
Why do plants need a good supply of magnesium ions?
Magnesium ions are required to synthesise chlorophyll, which absorbs light energy during photosynthesis. As a result, the leaves cannot photosynthesise properly and they turn yellow (chlorosis).
What are the symptoms of disease in plants?
● Stunted growth (lack of nitrate ions)
● Spotted leaves
● Decay/rotting
● Growths
● Malformation of stems/leaves
● Discolouration
● Presence of pests
What are three ways in which plant disease can be identified?
● Reference to a gardening website or manual
● Laboratory testing
● Monoclonal antibody test kits
Give examples of physical defence responses used by plants
● Cellulose cell walls
● Tough waxy cuticle on leaves
● Outside layer on stems/bark on trees
● Leaf fall
Give examples of chemical defence response used by plants
Antibacterial chemicals
Poisons
Give examples of mechanical defence responses used by plants
● Thorns and hairs to deter animals
● Leaves that droop/curl on contact
● Mimicry to trick animals
How do virus cause the symptoms of disease?
Viruses reproduce inside cells, damaging them
Why are viruses are not classed as cells?
They don’t have a cell and they don’t have cytoplasm, nucleus, mitochondria, ribosomes
What does a vaccine contain?
a weakened form of a virus (pathogens)
Which part of a plant shows discoloured caused by TMV?
Leaf
Why does a high level of TMV infection reduces growth in a plant?
Less chlorophyll so less glucose/starch/protein made
What causes the green colour in the stem?
Chlorophyll/chloroplasts
What name is given to a group of tissues working together?
Organs
What is penicillin?
An antibiotic discovered by Alexander Fleming that is made from Penicillium mould
What is digitalis?
A heart drug that originates from foxglove plants
What is aspirin?
A painkiller that originated from willow trees
What is pharmaceutical industry?
Businesses that develop and produce drugs for use in medicine and health care
What is toxicity?
The harmful effects of a drug
What is efficacy?
The effectiveness of a drug
What is a dose?
The recommended quantity of a drug
What is the preclinical testing?
Drug tests carried out in a laboratory on cells, tissues and live animals
What is the first stage of clinical trials?
A trial to measure the safety of a drug by testing on a sample of healthy individuals
What is the second stage of clinical trials?
A trial to measure the efficacy of a drug by testing on individuals that are unwell and in need of the drug treatment
What is the third stage of clinical trials?
A trial with many individuals to evaluate the overall safety and efficacy of a drug in comparison to existing drugs
What is a blind trial?
A trial in which participants are unaware of whether they have received a treatment or a placebo
What is a double blind trial?
A trial in which neither the experimenter nor the patient knows who is getting the research treatment to prevent bias
What is a placebo?
A fake drug used in the testing of medication to determine the efficacy of a real drug
What is lymphocyte?
The white blood cell responsible for antibody production
What is an antibody?
A protein that binds to a specific antigen and triggers the pathogens to be destroyed
What is the antibody production?
When a white blood cell called a lymphocyte produces antibodies
What is antigen?
A substance on a foreign cell or pathogen that triggers an immune response
What is a memory cell?
A white blood cell that recalls the structure of a specific antigen to prevent the body from being infected a second time
What is an active immunity?
The process of exposing the body to an antigen or pathogen to generate an adaptive immune response
What is a primary response?
The reaction of the immune system when exposed to a pathogen for the first time
What is secondary response?
The very quick reaction of the immune system when exposed to the same pathogen for a second time
What is an antibiotic-resistant strain?
A strain of bacteria that has mutated and is no longer treatable with standard antibiotics
What is an antiviral drug?
A class of medication used to treat viral infections
What is non-specific defence?
A general defence that works the same against all pathogens
What is immune system?
The cells and tissues that recognize and attack foreign substances in the body
What is phagocytosis?
When a white blood cell called a phagocyte engulfs a pathogen to destroy it with enzymes
What is antimicrobial secretions?
Secretions from the skin and nose that reduce bacterial growth
What is mucus?
A thick and sticky substance produced by goblet cells in the body, traps invasive pathogens and particles
What is cilia?
The hair-like projections on the outside of trachea cells that move mucus and other substances away from the lungs
What is stomach acid?
Hydrochloric acid in the stomach that kills pathogens
What is antigen?
A substance on a foreign cell or pathogen that triggers an immune response
What is lymphocyte?
The white blood cell responsible for antibody and antitoxin production
What is phagocyte?
The white blood cell responsible for phagocytosis via ingestion
What is protist?
A eukaryotic organism that cannot be classified as an animal, plant or fungus
What is fungi?
An organism that absorbs nutrients from the environment
What is toxin?
A poison that is harmful to organisms and is produced by pathogens such as bacteria
What is human immunodeficiency virus (HIV)?
A virus with flu-like symptoms that is spread by the exchange of bodily fluids and can lead to AIDS
What is acquired immunodeficiency syndrome (AIDS)?
A disease in which the immune system is severely weakened and cannot fight infection
What is tobacco mosaic virus?
A plant virus which causes a mosaic pattern on the leaves which slows photosynthesis and therefore growth
What is droplet infection?
An infection that is transmitted by sneezing and coughing pathogens carried by droplets in the air
What is airborne transmission?
Some infectious agents can be transmitted through the air over time and distance
What is sexually transmitted infection (STIs)?
Also called sexually transmitted diseases or STDs, the term used to describe infections that are spread through sexual activity such as intercourse
What is ingestion?
Infection can occur when eating uncooked products such as meat, drinking dirty water or touching the mouth after touching a dirty surface, some pathogens can survive in the extreme pHs of the digestive system
What areas of the body that pathogens can enter?
Nose and mouth, respiratory system, digestive system, reproductive or urinary systems, eyes and tear ducts, any orifice, via injection to the blood, through wounds or damage to the skin
What is monoclonal antibody?
A laboratory-produced antibody that is designed to target and bind to specific antigens
What is a clone?
A group of genetically identical cells
What is a mouse lymphocytes?
White blood cells that are used to make monoclonal antibodies
What is B lymphocytes?
White blood cells which can produce specific antibodies but can’t divide
What is a tumour cell?
A long-lived cell that divides continuously
What is a hybridoma cell?
A cell used to make monoclonal antibodies that is made by fusing a lymphocyte and a tumour cell
What is a pregnancy test?
Monoclonal antibodies can be used to detect pregnancy hormones in urine
What is laboratory test?
Monoclonal antibodies can be used to detect hormones, chemicals and pathogens in laboratory tests
What is fluorescent dye?
Can be added to monoclonal antibodies to help locate and detect substances
What is cancer treatment?
Radioactive substances or toxic drugs can be added to monoclonal antibodies to be delivered to tumours
What is a radioactive substance?
A chemical that releases radiation to kill cancer cells
What is a toxic drug?
A chemical that is toxic to cancer cells
What is a diagnosis?
A way of using monoclonal antibodies to identify diseases
What are physical defences?
Barriers that reduce the invasion of pathogens
What are cellulose cell walls?
Strengthen plant cells to help resist pathogens
What is a waxy cuticle?
The surface of a leaf which act as a barrier to pathogens
What are layers of dead cells?
A protective layer that can fall off a plant and take pathogens with them
What is bark?
A protective layer on the trunks of trees which act as a barrier to pathogens
What are chemical defences?
Chemicals that protect plants against pathogens
What are antibacterial chemicals?
Chemicals that protect plants against bacterial infections
What are poisons?
Chemicals to deter herbivores from grazing on plants
What are mechanical adaptations?
Physical adaptations such as thorns that prevent damage to plants
What are thorns?
Sharp growths which prevent damage from herbivores
What are plant cells?
Can irritate the mouth of herbivores which makes the plant difficult to eat
What are touch-sensitive leaves?
Leaves droop or curl which can dislodge insects or deter large herbivores
What is mimicry?
Plants mimic unhealthy or dangerous plants to prevent damage
What is an identification reference?
A source of information such as a gardening manual or website that can be used to identify plant diseases
What is a laboratory test?
A process where plant diseases can be detected
What is a testing kit?
A kit to test for specific diseases and deficiencies
What are monoclonal antibodies?
Can be used in testing kits to identify plant diseases
What are reduction in disease spread?
One of the aims of treating diseases plants
What are pesticide?
A substance which kills pests like aphids
What is fungicide?
A substance which kills fungal infections like rose black spot
What is removal?
If a plant cannot be treated it must be removed from the area
What is stunted growth?
Growth that is not in keeping with average rates
What are the spots of leaves?
Discoloured areas on leaves that are symptoms of disease in plants
What are the areas of decay?
Areas of rot in a plant that are symptoms of disease in plants
What is growth?
Uncontrolled cell growth which is a symptom of disease in plants
What are malformed stems and leaves?
When stems and leaves are not the correct shape or size
What are discolouration?
When plant tissues are the incorrect colour
What is the presence of pests?
When pests like aphids cover or infest a plant
What is the horticulturist?
An expert in plant cultivation and management
What is an insect?
A small invertebrate animal that can be a source of plant infection
What is ion deficiency?
A lack of mineral ions that can lead to specific issues in a plant
What are optimum conditions?
The conditions needed for an organism to thrive such as ideal mineral content in the soil for plant development
What is stunted growth?
Growth that is not in keeping with average rates
What is aphids?
An insect pest that infests plants and feeds from the phloem using needle-like mouthparts
What is nitrate deficiency?
Causes stunted growth in plants
What is magnesium deficiency?
Causes chlorosis in plants
What is chlorosis?
Yellowing of leaves
What are nitrate ions?
Needed by plants to synthesise proteins for growth
What are magnesium ions?
Needed by plants to make chlorophyll for photosynthesis
