B3 Infection & Response Flashcards
(97 cards)
<p>Name four ways in which diseases caused by pathogens can be spread</p>
<ol><li>Through air</li><li> Through water</li><li>Direct contact (e.g. STDs)</li><li>Vectors</li></ol>
<p>Name four ways in which the spread of diseases can be reduced or prevented</p>
<ol><li>Hand-washing</li><li>Safer sex practices</li><li>Vaccination</li><li>Eradication of vectors</li><li>Isolation of infected individuals</li></ol>
<p>What is a pathogen?</p>
<p>A microorganism that causes infectious disease</p>
<p>Name the four classes of pathogens</p>
<ol><li>Viruses</li><li>Bacteria</li><li>Protists</li><li>Fungi</li></ol>
<p>Why is there a short delay between infection by a pathogen and feeling ill from the infection? </p>
<p>Bacteria and viruses need to reproduce rapidly inside the body before there are enough of them to have an effect</p>
<p>Why might viruses cause more damage than bacteria?</p>
<p>Viruses live and reproduce inside cells, causing cell damage</p>
<p>In what way might bacteria cause damage to cells and tissues?</p>
<p>Bacteria may produce poisons (toxins) that damage tissues and make us feel ill</p>
<p>What are the symptoms of the measles virus?</p>
<p>Fever and a red skin rash</p>
<p>How is the measles virus spread?</p>
<p>Inhalation of droplets from sneezes and coughs</p>
<p>Why are children vaccinated against the measles virus?</p>
<p>Measles is a serious illness that can be fatal if complications arise</p>
<p>What are the initial symptoms of HIV infection?</p>
<p>HIV initially causes a flu-like illness</p>
<p>What is the aim of antiretroviral drugs?</p>
<p>To stop the HIV virus from replicating</p>
<p>How does HIV lead to AIDS?</p>
<p>When the body's immune system becomes so badly damaged it can no longer deal with other infections or cancers</p>
<p>How is HIV spread?</p>
<p>Sexual contact or exchange of body fluids such as blood which occurs when drug users share needles</p>
<p>What is TMV and what type of organism does it affect?</p>
<p>A widespread plant pathogen affecting many species of plants including tomatoes</p>
<p>What are the symptoms of TMV?</p>
<p>A distinctive ‘mosaic’ pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis</p>
<p>How does Salmonella cause disease and what are the symptoms?</p>
<p>Spread by the bacteria being ingested in food, or on food prepared in unhygienic conditions. Fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete</p>
<p>How is the spread of Salmonella controlled in the UK?</p>
<p>In the UK, poultry are vaccinated against Salmonella to control the spread</p>
<p>How is the bacterial disease Gonorrhoea spread?</p>
<p>Gonorrhoea is spread by sexual contact</p>
<p>How can the spread of the bacterial disease Gonorrhoea be controlled?</p>
<p>Treatment with antibiotics or use of a barrier method of contraception e.g. condom</p>
<p>What are the symptoms of Gonorrhoea?</p>
<p>Thick yellow or green discharge from the vagina or penis and pain on urination</p>
<p>What issues are there with the treatment for Gonorrhoea?</p>
<p>Was easily treated with the antibiotic penicillin until many resistant strains appeared</p>
<p>What is rose black spot disease?</p>
<p>A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early</p>
<p>How is rose black spot spread?</p>
<p>It is spread in the environment by water or wind</p>
How does rose black spot affect a plant?
It affects the growth of the plant as photosynthesis is affected due to discolouration & destruction of the leaves
How can rose black spot be treated?
Using fungicides and/or removing and destroying the affected leaves
What causes malaria?
A protist
How is malaria spread?
Spread via mosquito
How is malaria treated?
Anti-malarial drugs
How is the spread of malaria controlled?
Eradication of vectors such as mosquitos and/or use of mosquito nets at night to avoid being bitten
What are the four first line non-specific defence systems of the human body against pathogens?
- Skin
- Nose
- Trachea and Bronchi
- Stomach
What is the role of the immune system?
If a pathogen enters the body the immune system tries to destroy the pathogen
Name three ways in which white blood cells help to defend against pathogens
- Phagocytosis
- Antibody Production
- Antitoxin Production
What is Phagocytosis?
Phagocytosis is the process when a White blood cell engulfs a pathogen
What is the purpose of vaccination programmes?
Can prevent illness in an individual and reduces spread of the pathogen in a population
What does a vaccination contain?
A small quantity of dead or inactive forms of a pathogen
How does the contents of a vaccine prevent future infection?
It stimulates the white blood cells to produce antibodies. If the same pathogen re-enters the body the white blood cells respond quickly to produce more of the correct antibodies quickly, preventing infection
How do antibiotics work?
Killing infective bacteria inside the body through many different ways e.g. preventing the cell wall from forming or preventing DNA from being replicated
What are the current concerns around antibiotic treatment?
The emergence of bacterial strains resistant to antibiotics means many antibiotics no longer work effectively
What are painkillers used for?
Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens.
What are the issues with treating viral diseases?
Antibiotics cannot kill viral pathogens. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues
Name three examples of drugs extracted from plants and microorganisms and state what they are used for.
- The heart drug digitalis originates from foxglove plants
- The painkiller aspirin originates from willow trees
- Penicillin was discovered by Alexander Fleming from the Penicillium mould
How are most drugs manufactured now?
Synthesised by chemists in the pharmaceutical industry (However, the starting point may still be a chemical extracted from a plant or microorganism)
Why do new drugs need to be tested and trialled?
New drugs are extensively tested for toxicity, efficacy and dose to check that they are safe and effective
What is preclinical testing?
Preclinical testing is done in a laboratory using cells, tissues and live animals
What is involved in the first stage of a clinical trial?
Clinical trials use small numbers of healthy volunteers and patients. Very low doses of the drug are given at the start of the clinical trial
If a drug is found to be safe in the first stage of testing, what happens next?
If the drug is found to be safe, further clinical trials on larger groups of healthy volunteers and patients are carried out to find the optimum dose for the drug
What is a double-blind trial?
In double-blind trials, some patients are given a placebo. Neither the doctor nor patient knows whether they have been given a placebo in order to reduce potential bias
How are monoclonal antibodies made?
From a single clone of B-lymphocyte (B-cell) cell
What do antibodies recognise?
Antigens - part of a specific chemical or cell in the body
What name is given to the section of the antibody that recognises the antigens?
The antigen binding site
What is a hybridoma cell?
The combination of a lymphocyte and a tumour cell
Why are hybridoma cells created?
They have the ability to create the required antibody and divide rapidly
Once one hybridoma is made, what is then done with it?
Cloned to create many identical cells
Name 4 possible uses of monoclonal antibodies
- For pregnancy tests/diagnosis
- Measurement of hormone/chemical/pathogen levels in the blood
- Research to identify specific molecules in cells or tissues by binding with fluorescent dyes
- Treatment of some diseases like cancer
How can antibodies be used to treat conditions such as cancer?
Bind radioactive/toxic substances that are able to stop cells growing and dividing. The antibody will bind specifically to the cancer cells and deliver the substances without harming the other body cells
Name three ways of visually detecting a plant disease
- Stunted growth
- Spots on leaves
- Areas of decay (rot)
- Growths on part of the plant
- Malformed stems or leaves
- Discolouration
- The presence of pests
Name three ways to identify a plant disease
- Look symptoms up in a gardening manual or website
- Taking the infected plant to a laboratory
- Using a testing kit that contains monoclonal antibodies
Name four possible causes of plant diseases
- Viruses
- Bacteria
- Fungi
- Insects
How do aphids damage plants?
Pierce stems with their mouthparts to drink sugary liquid in phloem, introduce pathogens and deprive plants of sugars
Name two problems caused in plants by an ion deficiency
- Stunted growth caused by nitrate deficiency
- Chlorosis caused by magnesium deficiency
Why does a lack of nitrate ions affect plant growth?
Nitrate ions are used to make proteins
Why does a lack of magnesium ions affect plant growth?
Magnesium ions are used to make chlorophyll
Name three physical defences of plants
Cellulose cell walls, tough waxy cuticle on leaves, layers of dead cells around stems (bark on trees) which fall off
Name two chemical defences of plants.
- Antibacterial chemicals
- Poisons to deter herbivores
Name three mechanical defences of plants.
- Thorns and hairs deter animals
- Leaves which droop or curl when touched
- mimicry to trick animals
What is Herd Immunity?
Herd immunity is a form of indirect protection from disease as a large majority of the population is immune to the disease. This provides a form of protection to the people that aren't immune as the people around them do not carry the disease
What is Health?
Health is the state of physical and mental wellbeing of an organism
What are Communicable Diseases?
Communicable diseases are diseases that can be spread between organisms
What are Non-Communicable diseases?
Non-Communicable diseases are diseases cannot be spread between organisms
What is a Vector?
A vector is an organism that carries a pathogen without being infected by them
How do fungi spread and infect plants and animals?
- Fungi are unicellular or multicellular organisms that each have bodies made up of hyphae (thread-like structures)
- The hyphae are able to grow and penetrate tissues, such as human skin or the surface of plants
- The hyphae produce spores, which can spread to other plants and animals
How does Vaccination work?
- A vaccination injects a dead or inactive form of a pathogen into the blood
- White blood cells recognise that the antigens are foreign and produce antibodies against them
- Some of these white blood cells remain in the blood as memory cells. If the same pathogen invades the body again, the memory cells are able to:
- Produce antibodies faster
- Produce more antibodies, meaning that the antibody concentration remains in the blood for longer
- Next time the same pathogen infects the vaccinated person, it will be destroyed by the immune system before it can cause illness
How do you prevent resistant strains of bacteria from forming?
- Doctors should only prescribe antibiotics if they are needed and not for minor infections or viral infections
- Patients should complete their course of antibiotics to ensure all bacteria are killed
How does resistant bacteria form?
Whithin a population of bacteria, some will mutate randomly. The mutated bacteria are resistant to antibiotics so are able to survive. The resistance bacteria are able to reproduce rapidly as their competition has been killed by the antibiotics. All the copies are genetically identical, so also resistant to the antibiotic
Where is the drug Digitalis extracted from?
Digitalis is extracted from foxgloves
What is the drug Digitalis used for?
Digitalis is used to help heart disease as it strengthens the contractions of the heart
Where is Aspirin extracted from?
Aspirin is extracted from the bark of willowtrees
What is Aspirin used for?
Aspirin is a painkiller
Where is Penicilin extracted from?
Penicilin is taken from the mould of Penicilium
Who discovered Penicilin?
Alexander Fleming
What is Penicilin used for?
Penicilin is an anti-biotic, which treats bacterial infection
How are drugs now discovered?
Nowadays, most drugs are synthesised (made) by chemists in the pharmaceutical industry But the ingredients of these drugs may be chemicals extracted (taken) from plants
What are Anitviral drugs used for?
Anitviral drugs are used to treat viral infections
What are painkillers used for?
Painkillers are used to relieve pain caused by an infection
What is efficacy?
Efficacy is the effectiveness of the drug, how well the drug cures the disease
What is a drug tested on?
- Toxicity
- Efficacy
- Dosage
What is Preclinical Testing?
Preclinical testing is the stage before clinical testing takes place, testing if the drug is safe by using it on human cells, tissue and animals
What is Clinical Testing?
Clinical Testing is when the drug is tested on healthy volunteers and patients to check if the drug is safe. A low dosage of the drug is used
What is Optimum Dosage?
Optimum Dosage is the best amount of the drug to be taken to produce the desired effect
How is the Optimum dosage of a drug found?
After the drug is tested on healthy volunteers, the dosage is increased to find a rough dose. The drug is then tested on non-healthy patients and the dosage is varied slightly to find the optimum dose
What is a Placebo?
A placebo is an inactive substance that is used a control in clinical testing
What is a double-blind trial?
A double-blind trial is when neither a patient nor doctor knows which patient has received the drug and which has received the placebo
What is the point of a double-blind trial?
A double-blind trial removes bias from the test as neither doctor or patient can skew the results. All conditions are kept the same so that only the drug has an impact on the patient's health
How do you porduce Monoclonal Antibodies?
- A mouse is injected with the chosen antigen (obtained from a pathogen)
- The mouse’s immune system responds by producing lymphocytes (white blood cells) that produce the particular antibodies against that antigen
- The lymphocytes are extracted from the mouse and fused (combined) with myeloma cells (tumour cells) to form hybridoma cells
- The myeloma (tumour) cells grow rapidly and lots of identical cells are produced. All of the hybridoma cells produce the same antibody
- These monoclonal antibodies are collected, purified and can then be used to target specific cells and chemicals
