infection and response Flashcards
What are pathogens?
Microorganisms that cause disease
Four types: viruses, bacteria, fungi, protists
What are the two differences between viruses and bacteria?
- Viruses are smaller than bacteria
- Pathogenic bacteria are the minority, but all viruses cause diseases
How do bacteria cause disease?
They divide rapidly (through binary fission) and produce toxins that affect the body and make you feel ill, sometimes directly damaging cells
How do viruses cause disease?
They live and reproduce inside cells, damaging and destroying them
How can pathogens be spread?
- Air (e.g., coughing, sneezing)
- Direct contact (e.g., sexual contact, vectors)
- Water
What are five methods to prevent the spread of communicable diseases?
- Hand-washing
- Using disinfectants on surfaces
- Keeping raw meat away from other food
- Isolating an infected person
- Vaccination
What is measles?
A viral disease spread by inhalation of droplets, with symptoms including fever and red skin rash, prevented by vaccination
What is HIV?
A viral disease spread by sexual contact or sharing needles, with flu-like symptoms that can lead to AIDS, controlled with antiretroviral drugs
What is the tobacco mosaic virus (TMV)?
A viral disease spread by plant contact or by insects as vectors, causing a mosaic pattern of discoloration on leaves
What is salmonella?
A bacterial disease spread by raw food or food prepared unhygienically, causing symptoms like fever and vomiting
What is gonorrhea?
A bacterial disease spread by sexual contact, characterized by yellow/green discharge, controlled with antibiotics
What is rose black spot?
A fungal disease spread by wind or water, causing purple/black spots on leaves that prevent proper photosynthesis
What is malaria?
A protist disease spread by vectors (mosquitos), with symptoms including fever and can lead to death
How do the nose, trachea, and bronchi defend against pathogens?
They secrete mucus and have hairs or cilia that trap particles containing pathogens
How does the skin defend against pathogens?
It covers the body and acts as a barrier, preventing pathogens from reaching underlying tissues
How does the stomach defend against pathogens?
Acid destroys harmful microorganisms in swallowed mucus
What are three ways that white blood cells defend against pathogens?
- Phagocytosis
- Antibody production
- Antitoxin production
What is phagocytosis?
When white blood cells ingest pathogens, digesting and destroying them using enzymes
How do antibodies work against pathogens?
They bind to specific antigens on pathogens, causing them to stick together and making phagocytosis easier
How do antitoxins work against pathogens?
They neutralize toxins released by bacteria
How can aphids affect plants?
They feed on dissolved sugars in phloem vessels and can act as vectors transferring pathogens
How can aphids be controlled?
- Chemical pesticides
- Releasing aphid-eating insects
How can nitrate deficiency affect plants?
Growth may be stunted, as nitrates are needed for protein synthesis
How can magnesium deficiency affect plants?
Without magnesium, plants cannot make chlorophyll, leading to yellowing (chlorosis) and stunted growth
How can diseases in plants be detected?
- Stunted growth
- Spots on leaves
- Areas of decay/rotting
- Discoloration
What are physical plant barriers that reduce the invasion of pathogens?
- Waxy cuticle layer
- Bark on trees
What are chemical barriers that help protect plants against pathogens?
Antibacterial chemicals that can be extracted for use as antibiotics
How can plants defend themselves from herbivores?
- Being poisonous
- Thorns
- Mimicking unhealthy/poisonous plants
What plant does aspirin come from?
Willow trees
What is immunisation?
Being protected against a disease by vaccination
How do vaccines work?
They contain a dead/inactivated form of the pathogen, stimulating antibody production
What is herd immunity?
A large proportion of the population being immune to a disease, reducing pathogen spread
What are antibiotics?
Medicines that kill infective bacteria inside the body
What are antiseptics?
Chemicals that kill microorganisms outside the body
What problem is beginning to arise with antibiotics?
Strains of bacteria resistant to antibiotics are evolving
Why is it difficult to develop drugs that kill viruses?
Because it is difficult to kill viruses without damaging body tissues
Where does the heart drug, digitalis, originate?
Foxgloves
Who discovered penicillin?
Alexander Fleming
What three aspects are drugs tested against during trials?
- Toxicity
- Efficacy
- Dosage
What does preclinical testing involve?
Testing drugs in a laboratory on cells, tissues, and live animals
What does the first stage of clinical testing involve?
Testing the drug on healthy individuals for safety and side effects
What does the second stage of clinical trials involve?
Testing the drug on patients to see if it treats the disease
What is a placebo?
A substance that looks like the drug being tested, but has no effect
What is a double blind trial?
When neither the doctor nor the patient know who is receiving the drug and who is receiving the placebo
Why are double blind trials used in clinical trials?
To eliminate bias from the doctors
What is a monoclonal antibody?
An identical antibody from the same immune cell, binding to one type of antigen
How are monoclonal antibodies made?
B-lymphocytes are fused with tumor cells to create hybridoma cells that produce identical antibodies
What are uses of monoclonal antibodies?
- Pregnancy tests
- Cancer treatments
- Measuring and monitoring
How can monoclonal antibodies be used to treat cancer?
They can trigger the immune system to attack cancer cells or block growth receptors
What are the advantages of using monoclonal antibodies?
- Bind to specific cells
- Can be engineered for different conditions
What are the disadvantages of monoclonal antibodies?
- Expensive to develop
- May trigger immune responses
- Difficult to attach to drugs
