B6.3 Flashcards
What is health?
The state of physical and mental wellbeing.
What is a disease?
A disorder that affects the body, organs, or cells.
What are the two types of disease?
Communicable and non-communicable.
What are communicable diseases?
Diseases caused by pathogens that can spread between people - contagious
Examples of communicable disease?
chickenpox, malaria, HIV
What are non-communicable diseases?
Diseases that do not spread between people - non contagious
Examples of non-communicable diseases?
diabetes, heart conditions, neurological diseases, cancer
What lifestyle factors cause non-communicable diseases?
Diet, stress, lack of exercise, alcohol
How does HIV affect susceptibility to disease?
Weakens the immune system so the body is more vulnerable to infections like TB.
What is tuberculosis (TB)?
A bacterial infection that mainly affects the lungs; more likely in HIV patients.
How is HPV linked to cancer?
The virus can live in cells and trigger cancers such as cervical cancer.
What do viruses do in the body?
Infect and live inside host cells, replicate DNA, burst out to infect other nearby cells.
Can antibiotics treat viral infections?
No
How does HIV spread?
Bodily fluids (e.g. sexual activity, sharing needles, from mother to baby:feeding)
Symptoms of HIV?
Initial flu-like symptoms
What does HIV develop into?
AIDS – immune system is damaged and fails
Prevention for HIV?
Use condoms, avoid sharing needles, bottle-feed babies of HIV+ mothers
Treatment for HIV?
No cure, but antiviral drugs slow progression to AIDS
What is a viral infection in humans?
HIV
What is a viral infection in plants?
Tobacco Mosaic Virus (TMV)
What does TMV do to plants?
Infects chloroplasts, reduces photosynthesis by creating mosaic white spots
How does TMV spread?
Contact between plants
How is TMV prevented?
Good field hygiene, pest control, grow TMV-resistant strains
What is a bacterial disease in humans?
Salmonella
What is Salmonella?
A type of food poisoning caused by bacteria in animal gut
Symptoms of Salmonella?
Fever, stomach cramps, vomiting, diarrhoea
Spread of Salmonella?
Raw meat, eggs, unhygienic food practices
Prevention of Salmonella?
Wash hands/surfaces, cook food thoroughly, avoid raw and cooked food contact
What is a bacterial disease in plants?
Crown gall disease
What does crown gall disease do?
Transfers bacterial DNA into plant’s DNA
Symptoms of crown gall?
Tumours develop in roots/stems, plant becomes stunted
What is a fungal disease in humans?
Athlete’s foot
Symptoms of Athlete’s foot?
Red or white flaky rash between toes
How does it spread?
Touching infected skin/surfaces, often in swimming pool changing rooms
Treatment for Athlete’s foot?
Antifungal medication
What is a fungal disease in plants?
Barley Powdery Mildew
What does barley powdery mildew do?
Affects grass plants like barley, plant will be unable to make chlorophyll so cannot photosynthesise
Symptoms of barley powdery mildew?
Circular fluffy white growth, spores spread by wind - hyphae produced on upper & lower leaf surfaces
Spread of barley mildew?
Common in cool, damp environments
Treatment barley mildew?
Fungicides, removing infected leaves
What is a protist disease in humans?
Malaria
What is malaria caused by?
Protists that infect red blood cells - pathogens replicate & RBCells burst to spread pathogen further
Symptoms of malaria?
Shivering and fever
How does malaria spread?
Female Anopheles mosquito (vector); saliva enters bloodstream
How is malaria prevented?
Insecticide nets, remove stagnant water, antimalarial drugs
How can communicable diseases be identified or reduced?
Visual identification
Screening for antibodies (e.g. HIV)
DNA identification (e.g. Agrobacterium)
What are physical plant defences?
Bark: barrier of dead cells
Cell wall: made of cellulose
Leaf cuticle: waxy layer to block pathogens
What are chemical plant defences?
Antimicrobial substances: e.g. mint, witch hazel – act as antiseptics
Poisons: e.g. stinging nettles release poison to avoid being eaten
What does ELISA Test stand for?
Enzyme-Linked Immunosorbent Assay
What is ELISA used for in plants?
To detect whether a plant contains a pathogen antigen - therefore if it’s infected
What are the 7 steps of ELISA?
- Liquidise plant sample
- Add sample to plastic tube/microtiter plate
- Leave for 5 mins so proteins in plant bind to plastic
- Wash the wells with buffered salt solution to remove unbound excess proteins
- Add blocking agent to block uncoated plastic, then wash again with salt solution
- Add antibody-enzyme complex specific to pathogen antigen, then wash again with salt solution
- Add colourless substrate – enzyme changes it to a coloured product if antigen is present
What PCR stand for
Polymerase Chain Reaction
What is PCR used for?
To copy small DNA sections billions of times.
What is added to the PCR tube?
2 primers, nucleotides, and DNA polymerase
What does DNA polymerase do?
Reads DNA, makes a copy by attaching nucleotides at a primer
What does 2 primers do?
they are short pieces of DNA, are needed to match each end of the DNA segment that is meant to be copied
What are the temperature stages of PCR?
95°C: DNA heated to 95 to unzip DNA and denature
55°C: DNA cooled to 55 to allow primers to anneal
72°C: DNA heated to optimum temp for DNA polymerase to work
What is observation used for in plant disease detection?
Look, feel, smell of plants – check for fungus, stunted growth, etc.
What is the purpose of non-specific defences?
Prevent pathogens from entering the body.
What are the 5 main non-specific defences?
Skin
Nose
Trachea and bronchi
Stomach
Phagocytic white blood cells
Skin - non specific defence - what does it do?
- acts as physical barrier
- Produces antimicrobial secretions to kill pathogens
- Contains skin flora (good microorganisms that outcompete pathogens for space & nutrients’)
Nose - non specific defence - what does it do?
Hairs and mucus trap particles - prevents them from entering lungs
Trachea and bronchi - non specific defence - what does it do?
Secrete mucus - trap pathogens
Cilia (hair like structures on cells) waft & move mucus upwards to be swallowed
Stomach - non specific defence - what does it do?
Produces hydrochloric acid to kill pathogens
Phagocytic white blood cells - non specific defence - what does it do?
Do phagocytosis: engulf and digest pathogens (non-specific - can do for any pathogen)
What are the 2 specific functions of white blood cells?
Produce antibodies (lymphocytes) Produce antitoxins
What does the white blood cell lymphocytes do (antibodies)
Each pathogen has antigens on its surface - complementary antibodies can bind to it
Antibodies bind to specific antigens
Which Causes pathogens to clump together – easier for white blood cells to find
Upon reinfection, faster antibody production = immunity
What do antitoxins from white blood cells do?
Allows WBCells to neutralise toxins released by pathogens by binding to them
What are platelets?
Blood components that help form clots.
How do platelets form clots?
Have surface proteins to clump together
Trigger a clotting cascade (chain of chemical reactions)
What are monoclonal antibodies?
Identical antibodies from the same lymphocyte that bind to one specific antigen.
What are the 6 steps to make monoclonal antibodies?
- Inject antigen into a mouse
- Mouse produces lymphocytes against specific antigen
- Remove spleen cells (where lymphocytes are made)
- Spleen cells combine with cancerous myeloma cells → form hybridoma
- Hybridoma clones itself to produce lots of same antibody
- Antibodies are collected and purified
What hormone do pregnancy tests detect?
hCG – human chorionic gonadotrophin
What are the 2 sections of a pregnancy test?
1st section - Mobile antibodies: Complementary to hCG, attached to blue beads
2nd section - Stationary antibodies: Fixed in place, also bind hCG
What happens when hCG is present? - pregnancy tests
hCG binds to mobile antibodies → forms hCG-antibody complex
Complex is carried to stationary antibodies
As they are each bound to a blue head:Blue line appears → positive result
How do monoclonal antibodies help detect cancer?
Bind to antigens on cancer cells, cause them to clump
Can carry fluorescent dye to highlight tumour location
How do monoclonal antibodies treat cancer?
Drugs are attached to deliver toxic substances directly to tumour
Encourage WBCs to attack cancer
Advantages of Monoclonal Antibodies
Bind to specific cells only – healthy cells unaffected
Can be engineered for many conditions
Mouse-human hybrid cells reduce immune response risk
Disadvantages of Monoclonal Antibodies
Hard to attach them to drugs
Expensive to develop
May trigger immune response in humans (from mouse lymphocytes)
What is a vaccine?
dead/inactivated form of pathogen that triggers an immune response.
How do vaccines protect against disease?
WBCs make complementary antibodies
On reinfection: faster antibody production, no symptoms
Creates immunity
What is herd immunity?
Immunising a large % of the population so fewer people catch and spread the disease.
What have vaccinations achieved so far?
Eradicated many diseases (e.g. smallpox)
Reduced occurrence of others (e.g. rubella)
How do vaccinations help prevent epidemics?
Through herd immunity, reducing lots of cases in an area
What is a disadvantage of vaccination?
Not always effective in providing immunity
What rare side effects can vaccines cause?
Bad reactions like fevers (very rare)
What are antibiotics used for?
Kill bacterial pathogens inside the body
Do not damage body cells
Why can’t antibiotics be used to treat viruses?
Viruses live inside body cells, so targeting them would damage tissue
How can antibiotics be taken?
Pill
Syrup
Directly into bloodstream
Why is it important to use the correct antibiotic?
Different antibiotics target different bacteria types
What is the impact of antibiotics on health?
Reduced deaths from bacterial diseases (e.g. Penicillin)
What causes antibiotic resistance?
Mutations during reproduction make bacteria resistant
What happens when bacteria are exposed to antibiotics?
Only non-resistant ones die
Resistant bacteria survive and reproduce
What is the problem with antibiotic resistance?
Previously effective antibiotics no longer work
Makes bacterial infections hard to treat
How can resistance be prevented?
Avoid overuse of antibiotics
Always complete the full course of treatment
What are antivirals used for?
Treat viral diseases
Stop virus replication
Why is killing viruses difficult?
Viruses hijack cells to replicate
Killing the virus may damage human cells
How do antivirals work?
Prevent the virus from copying its DNA
Stop replication
What are antiseptics?
Chemicals that kill foreign microorganisms
Where are antiseptics commonly used?
To sterilise wounds
Prevent infection and disease spread
Why are antiseptics and antibiotics tested on agar plates first?
To check their effectiveness
Why are aseptic techniques used?
Prevent contamination of pure cultures
Ensure accurate results
What is done to the workspace before beginning?
Cleaned and sprayed with disinfectants
How are petri dishes and agar gel sterilised?
In an autoclave
What is done after agar is poured?
Allowed to set in sterile petri dishes
Why work around a blue Bunsen flame?
Creates an updraft to stop airborne bacteria from contaminating
How is the bacterial suspension prepared?
Swirled (not shaken)
How is the inoculating loop sterilised?
Heated in a blue Bunsen flame or cleaned with pure alcohol
Why flame the neck of the bacterial bottle?
To kill unwanted bacteria
How are separate bacterial colonies made?
Dip loop in solution and streak on agar plate
How should the petri dish be stored?
Lid taped on
Labelled on the bottom
Stored upside down
Why shouldn’t the petri dish be fully sealed?
So oxygen can enter and bacteria can respire aerobically
What temp should the plate be incubated at? Why?
Max 25°C
Reduces harmful bacterial growth (pathogens grow at 37°C)
What happens after the experiment?
Dispose of contaminated materials
Disinfect surfaces
What is the zone of inhibition?
Area around antibiotic where bacteria stopped growing
How is the zone of inhibition measured?
Measure diameter
Divide by 2 to find radius
Use area of circle formula: πr²
What does a larger zone of inhibition mean?
More effective antibiotic or antiseptic
Where do most new drugs come from?
Plants used in traditional healing
Example of a plant-based medicine?
Willow bark used for fever → now used to make aspirin
Why is rainforest destruction a concern for medicine?
May destroy plants/organisms that could help modern medicine
What are preclinical drug trials?
Tests using computer models or human cells to see drug effects before animal/human testing.
Why are preclinical trials important?
To check safety on living cells before testing on animals.
Is animal testing for medicine legal in the UK?
Yes, but not for cosmetic products.
Why are drugs tested on animals?
To observe side effects and adjust dosage.
What are human clinical trials?
Tests on healthy volunteers, then target patients in increasing doses.
What is a placebo?
An inactive version of the drug used to compare against the real drug in trials.
What is a blind trial?
Patients don’t know if they receive the real drug or placebo—helps test drug’s true effect.
What was Thalidomide and why was it dangerous?
A sleeping pill given to pregnant women, caused birth defects due to lack of proper testing.
What are non-communicable diseases (NCDs)?
Diseases not spread between people, e.g., CVD, cancer, type 2 diabetes, liver disease.
How does obesity affect health?
Increases blood pressure and insulin resistance, raising type 2 diabetes risk.
What liver damage does alcohol cause?
Fatty liver - lipids to build up
alcoholic hepatitis - liver becomes inflamed
liver cirrhosis - scarred liver - no longer function
What brain effects can alcohol cause?
Brain shrinkage, memory loss, psychiatric problems.
How does smoking increase CVD risk?
Damages artery lining, increases fatty build-up, risk of heart attacks/strokes.
How do chemicals in cigarettes affect the heart?
Increase blood clots and heart rate (nicotine), reduce oxygen (carbon monoxide).
What can carcinogens in cigarettes cause?
Lung cancer.
What is COPD and how is it caused?
Chronic Obstructive Pulmonary Disease caused by inflammation and mucus in lungs - hard to breathe
What causes heart attacks?
Cholesterol and fatty deposits block coronary arteries, stopping oxygen to the heart.
What are symptoms of heart attacks?
Chest pain (angina), heart tissue dies if untreated.
Risk factors for CVDs?
Smoking, high blood pressure, high salt/saturated fat in diet.
Lifestyle choices to treat CVD?
Exercise, no smoking, lose weight, less saturated fat.
What are statins?
Drugs that reduce cholesterol production in the liver.
Who are statins given to?
Those with heart disease or high risk.
Side effects of statins?
Must be taken long-term; not suitable for people with liver disease.
What are stents?
Wire mesh tubes inserted to keep arteries open; made of metal alloys (avoid immune rejection).
What is coronary artery bypass surgery?
Graft from another body part creates new path for blood around blockage.
When is a heart transplant needed?
For heart failure—when it can’t pump blood effectively.
What is the risk of heart transplants?
Long wait, rejection risk, need for immunosuppressants (↑ infection risk).
What are artificial hearts used for?
Temporary support while waiting for transplant.
What is cancer?
Uncontrolled cell growth and division.
What is a benign tumour?
Grows slowly, doesn’t spread, can be removed.
What is a malignant tumour?
Grows quickly, cancerous, spreads via bloodstream (metastasis).
Cancer risk factors?
Carcinogens, age, genetic factors (e.g. BRCA1), HPV, smoking.
Lifestyle factors that increase cancer risk?
Alcohol (liver), UV radiation (skin), asbestos exposure.
What are stem cells used for in medicine?
Replace damaged cells (e.g. type 1 diabetes, paralysis), grow organs.
What are bone marrow transplants used for?
Treat blood cancers like leukaemia.
Advantages of stem cells?
Can grow whole organs, no rejection if from body.
Risks of stem cells?
Ethical issues, mutations, hard to find donors, uncertain success.
What is genetic engineering used for in medicine?
Make insulin, treat inherited conditions, and test for diseases.
How is insulin produced using genetic engineering?
Gene cut with restriction enzymes, inserted into plasmid, taken up by bacteria via binary fission.
How can inherited conditions be treated?
Replace faulty gene with working one via genetic engineering.
What is Huntington’s disease?
Genetic disease tested before symptoms show, helps with family planning.
What is the Human Genome Project?
Research to identify all human genes.
Benefits of the Human Genome Project?
Understand genetic causes of disease, predict likelihood, and improve drug effectiveness.
