Unit 3 - Infection and Response - Communicable Diseases Flashcards
What are the two major categories of diseases?
- Communicable (infectious)
- Non-communicable
Define communicable diseases.
Diseases that can be passed from one organism to another
Give an example of a communicable disease.
The flu
Define non-communicable diseases.
Diseases that cannot be transmitted from one person to another
Give an example of a non-communicable disease.
Heart disease
What are some factors that affect health?
- Diet
- Stress
- Life situations
How do bacteria reproduce?
By binary fission, splitting into two every twenty minutes
What do bacteria produce that can make you feel ill?
Toxins that damage your cells
How do viruses reproduce?
They take over host cells, reproduce inside them, and then destroy the cells
What are pathogens?
Microorganisms that can cause disease
What are the different types of pathogens
- bacteria
- fungi
- virus
- protist
What are the three ways that pathogens are spread from one individual to another
- By air
- By direct contact
- By water
What occurs during droplet infection/inhalation? (spread of disease through air)
Tiny droplets full of pathogens are expelled when a sick person coughs, sneezes, or talks, and others inhale these droplets
Examples of diseases spread by air
- influenza (flu)
- tubercolosis
- the common cold
How are diseases spread by direct contact?
Through direct contact of an infected organism with a healthy one
Examples of diseases spread by direct contact
- syhilis
- chlamydia
- HIV/AIDS
These are all examples of sexually transmitted diseases.
What is a common method for plant disease transmission?
By water
Fungal spores are often carried in splashes of water.
How can humans contract diseases through water?
By eating raw, undercooked, or contaminated food or drinking water containing sewage
Examples of diseases in humans spread through water
- cholera
- salmonellosis
These are all diarrhoeal diseases
What does culturing bacteria mean?
growing bacteria in a laboratory
What conditions are needed for culturing bacteria?
They need a source of nutrients, e.g. glucose, the right temp, pH, oxygen (aerobic)
What is sterile technique?
Ensures that you and the environment aren’t getting contaminated by the bacteria being cultured
Give some examples of precautions you might take for sterile technique.
- hand washing
- disinfect bench
- sterile agar/plates
How would you label a petri dish?
Label it with initials, name of bacteria
How do you fix the lid on a petri dish?
Seal it with a bit of tape on both sides
How should you store a petri dish?
Store it upside down so condensation doesn’t get into the bacteria
What is the maximum temperature for incubation of a culture in a school?
25°C
If the mean division time is 30 minutes, how many times will bacteria divide in 8 hours?
16 times.
Calculation: 8 hours x 2 divisions per hour = 16 divisions.
What is the equation to calculate the number of bacteria at the end of the growth period?
Bacteria at end = Bacteria at beginning x 2^number of divisions.
Calculate the number of bacteria after 8 hours if starting with 1 bacterium and a mean division time of 30 minutes.
65,536.
Calculation: 1 x 2^16 = 65,536.
List some factors that affect bacterial growth
- Optimum temperature. (enzymes)
- Optimum pH (enzymes)
- Nutrients availability (glucose)
- Oxygen availability → aerobic bacteria.
What happens during the Lag phase of bacterial growth?
No change in population size, no/very little cell division, cells are adjusting to the culture medium
What happens during the Exponential phase of bacterial growth?
Rapid increase in population due to plenty of resources available for cell division
What occurs during the Stationary phase of bacterial growth?
Population remains the same; cell division equals cell death
What is happening in the Death phase of bacterial growth?
Population size decreases due to cell death exceeding cell division
This is due to a lack or resources
What is the effect of high temperatures on bacteria?
High temperatures can kill bacteria by damaging their proteins and other essential molecules.
What is the effect of low temperatures on bacterial growth?
Low temperatures can slow down bacterial growth.
What is the purpose of disinfectants?
Disinfectants are chemicals that kill bacteria and other microorganisms.
Where are disinfectants commonly used?
Disinfectants are often used to clean surfaces, such as countertops and floors.
What are antiseptics used for?
Antiseptics are used to kill bacteria on the skin or other living tissue.
What are antibiotics?
Antibiotics are medicines that kill bacteria inside the body.
What types of infections are treated with antibiotics?
Bacterial infections
e.g pneumonia
What is an example of beneficial bacteria?
Bacteria in the gut help to digest food.
What is the first key way to help prevent the spread of communicable diseases?
Practicing good hgiene
List three hygiene practices to prevent the spread of communicable diseases.
- Wash hands
- Disinfect surfaces
- Face masks/handkerchiefs
What action should be taken if someone has an infectious disease?
Isolating infected individuals
It helps to prevent the spread of disease to other individuals
What are vectors?
Organisms that carry or spread a pathogen
How can we control the spread of diseases transmitted by vectors?
Destroying or controlling vectors.
What role does education play in preventing communicable diseases?
It allows people to develop an understanding of how the diseases are spread.
What are the symptoms of measles?
- Fever
- Rash
- Red irritated skin
- Can cause blindness/brain damage
How is measles spread?
Droplet inhalation (air) from coughs/sneezes
What is the treatment for measles?
No treatment
Prevention: isolation + vaccination
What are the initial symptoms of HIV/AIDS?
Mild, flu-like illness
How does HIV progress to AIDS?
HIV stays in the immune system until the immune system is badly damaged, leading to AIDS
How is HIV spread?
Via sexual contact & exchange of bodily fluids (blood)
What treatments are available for HIV/AIDS?
No treatment; no vaccine
What are some prevention methods for HIV?
- Using condoms
- Not sharing needles
- Screening blood
- HIV-positive mothers bottle-feeding their children
What is a key symptom of the Tobacco mosaic virus?
Distinctive ‘mosaic’ pattern of discoloration on the leaves
What impact does the Tobacco mosaic virus have on plants?
- Affects the growth of the plant
- Affected areas do not photosynthesize
- Destroys chloroplasts – less chlorophyll (less light absorbed)
How is the Tobacco mosaic virus spread?
By contact between diseased plant material and healthy plants; insects can act as vectors
What are the prevention methods for the Tobacco mosaic virus?
- Good field hygiene
- Good pest control
What are the symptoms of Salmonella infection?
Fever, abdominal cramps, vomiting, diarrhoea
How is Salmonella spread?
Eating undercooked food, raw meat, poultry, eggs, food prepared in unhygienic conditions
What is the treatment for Salmonella infection?
No treatment
Prevention: poultry in vaccinated
What preventive measures can be taken against Salmonella?
Keep raw chicken away from uncooked food, avoid washing raw chicken, wash hands and surfaces (main one)
What are the symptoms of Gonorrhoea?
Thick yellow or green discharge, pain on urination
What are the long-term consequences of untreated Gonorrhoea?
Pelvic pain, infertility, ectopic pregnancies
What is the treatment for Gonorrhoea?
Antibiotics
Prevention: using condoms/reducing the number of sexual partners
What happens when plants are infected by Agrobacterium tumefaciens?
Crown galls form, consisting of unspecialised cells
They are founf in roots + shoots
What is the recommended action when plants are infected with Agrobacterium tumefaciens?
Remove affected plants and clean equipment
What type of disease is Rose Black Spot?
Fungal disease
.
What are the symptoms of Rose Black Spot?
- Black/purple spots on leaves
- Yellowing of leaves
- Early leaf drop
- Reduced photosynthesis
- Poor flowering
How does Rose Black Spot spread?
- Water (rain)
- Wind (airborne transmission)
What is the treatment for Rose Black Spot?
Use fungicides to kill the fungi
What type of disease is Malaria?
Protist disease
What are the symptoms of Malaria?
- Fever
- Shaking
- Weakens the person over time
What is the vector for Malaria transmission?
Female Anopheles mosquito
What are the treatments for Malaria?
Anti-malarial drugs
What are some prevention methods for Malaria?
- Mosquito nets
- Insecticides
- Repellents
- Long clothing
- Vaccination
- Draining bodies of water
- Releasing sterile mosquitoes
What is an example of a pest that affects plants?
Aphids
What do aphids use to feed on plants?
Sharp mouthparts that pierce into the plant’s stem
What is the impact of aphids on plants?
- Found in large numbers
- Deprive the plant of sugar needed for energy and growth
- Act as vectors for disease pathogens
- Damage and weaken the plant, leading to stunted growth
What are two methods for removing aphids from plants?
- Insecticides
- Biological control (e.g., using ladybugs)
What are non-communicable diseases in plants caused by?
Mineral deficiencies in the soil
What is the role of nitrate (NO3-) in plants?
Needed for growth and repair
What does a deficiency of nitrate cause in plants?
- Less protein
- Less growth (stunted growth)
- Less yield
What is the role of magnesium (Mg2+) in plants?
Making chlorophyll
What are the effects of magnesium deficiency in plants?
- Cannot photosynthesize properly
- Leaves turn yellow (chlorosis)
- Stunted growth
What are the primary types of plant defense mechanisms?
Physical, chemical, and mechanical defenses
What is the role of cellulose cell walls in plant defense?
Prevent entry of microorganisms
How does the waxy cuticle on leaves contribute to plant defense?
Prevents microorganism entry
What is the function of layers of dead cells (bark) in plant defense?
Makes it difficult for microbes to penetrate
These parts also fall off, and takes the pathogens with them
What is leaf fall and its significance in plant defense?
Deciduous trees shed leaves in autumn to remove pathogens
What types of chemicals do plants produce for defense?
Antibacterial chemicals and poisons
Give an example of a mechanical adaptation in plants.
Thorns
How do thorns function as a defense mechanism?
Deter herbivores from feeding
What is the purpose of mimicry in plant defense?
Deter herbivores or insects from laying eggs
Describe the mimicry of a wasp and hoverfly.
Both have black and yellow stripes
This mimicry helps the hoverfly avoid predation and gain more access to nectar.
What reaction do drooping or curling leaves provoke in herbivores?
Make the plant appear unhealthy or react to touch
E.g mimosa plant
What is the importance of fast identification of plant diseases?
Leads to rapid treatment and prevents the disease from spreading
Name a visible pest that may indicate plant disease.
Caterpillars
What is the first step to identify plant diseases?
Observe symptoms
What are some treatment options for plant diseases?
- Pesticides or anti-fungal agents
- Fertilisers
- Removal and destruction
What is the purpose of using pesticides or anti-fungal agents?
To target specific pathogens
What is the role of the skin in human defense responses?
Acts as a barrier; tough/dry outer surface; sebum/oil repels pathogens
What function does mucus serve in the nose?
Traps pathogens in the air
What is the role of mucus in the trachea?
Traps pathogens in the air; moved out by cilia; swallowed into the stomach
What is the function of hydrochloric acid in the stomach?
Kills pathogens in mucus/food/drink
What is contained in tears that helps protect the eyes?
Natural antiseptic
What happens if pathogens get past non-specific defense systems?
White blood cells (WBC) of the immune system try to destroy them
What type of cells are lymphocytes and their function?
Make antibodies; large nucleus
What characterizes phagocytes?
Phagocytes engulf and digest pathogens; irregular nucleus
Identify the phagocyte and the lymphocyte
What is phagocytosis?
The process by which a cell engulfs a particle or another cell.
What happens to a pathogen during phagocytosis?
The pathogen is surrounded and engulfed by the phagocyte.
What are antibodies?
Proteins that bind to specific antigens (foreign substances) to help fight infection.
Where do antibodies travel after being produced?
Antibodies travel through the bloodstream to the site of infection.
What do antibodies bind to?
Antibodies attach to specific markers (antigens) on the surface of pathogens.
Are antibodies specific to pathogens?
Yes, each type of antibody is designed to target a specific pathogen.
What happens once antibodies are bound to a pathogen?
Antibodies destroy the pathogen
What do pathogens release that can be harmful?
Some pathogens release harmful substances called toxins.
What do WBCs produce to neutralise toxins?
White blood cells produce antitoxins that can neutralize these toxins.
What is the function of antitoxins produced by WBCs?
To neutralize the toxin/poison produced by pathogens.
What are memory cells?
Cells produced after encountering a pathogen that allow for a faster response if the same pathogen is encountered again.
What gives us immunity to certain pathogens or diseases?
Vaccination
What are antigens?
Chemical markers in cell membrane
What is the effect of vaccination on the primary immune response?
Stimulates lymphocytes to produce & release specific antibodies to pathogen
The vaccine contains a weak or dead form of the pathogen.
What happens in the secondary immune response?
You are immune to future infections by the same pathogen
Memory cells to the pathogen remain in blood
.
How does the secondary immune response differ from the primary response?
Response is sooner, antibodies are produced faster, greater concentration of antibodies, remain in blood for longer
What is herd immunity?
Most people are immune, reducing illness and disease spread
What are the benefits of herd immunity?
Less chance of a non-vaccinated individual being exposed to the pathogen
What do antibiotics do?
Kill bacteria and prevent/slow down cell division
What is the primary function of painkillers?
Relieve symptoms
What type of infections do antibiotics specifically target?
Bacterial infections
Antibiotics are ineffective against viral infections.
Why is it difficult to develop antiviral drugs?
Because it is challenging to kill viruses without also damaging the body’s tissues.
What is a major concern regarding bacteria and antibiotics?
Strains of bacteria that are resistant to antibiotics are evolving
This leads to antibiotics that previously killed specific bacteria becoming ineffective.
Define ‘antibiotic-resistant organism.’
A population of bacteria that is resistant to antibiotics.
What is a ‘non-resistant organism’?
An organism that is not resistant to antibiotics.
What are the characteristics of a good medicine?
- little/no side effects
- how it’s taken (e.g. tablets easier than injection)
- does it work?
- dosage
- speed of effect
- cost
What is the focus of pre-clinical drug testing?
Tests on cells, tissues, organs, followed by tests on laboratory animals
What is the focus of Phase 1 clinical trials?
- Test on healthy volunteers
- Low dosage to reduce risk
- Look for side effects
- Look for toxicity/safety
What is the focus of Phase 2 clinical trials?
- Small number of patients
- Look for side effects
- Look for toxicity/safety
- Double-blind trial using a placebo
- Efficacy and effectiveness
What is the focus of Phase 3 clinical trials?
Determine correct dosage with a large number of patients
What is a placebo?
A drug containing no active ingredients and no therapeutic effect
What is a double-blind trial?
A trial where neither the patient nor the doctor knows who is receiving the real drug and who is receiving the placebo
This helps prevent bias
What is the purpose of peer review?
To analyze results by peers to check validity and avoid bias
What are monoclonal antibodies?
Antibodies produced from a single clone of cells
Monoclonal antibodies are specific to what?
One binding site on one protein antigen
So, they are able to target specifical cells/chemicals in the body
How are monoclonal antibodies produced?
By stimulating mouse lymphocytes to make a particular antibody
What is a hybridoma?
A cell formed by combining mouse lymphocytes with a tumour cell
What capabilities does a hybridoma cell have?
It can both divide and make the antibody
What process is used to produce many identical hybridoma cells?
Cloning single hybridoma cells
So, a large amount of the antibody can then be collected + purified
What are monoclonal antibodies used for in pregnancy tests?
Diagnosis
What hormone do females produce during pregnancy that is tested for?
hCG
It is found in blood + urine
What is injected into a mouse to produce monoclonal antibodies specific to hCG?
hCG
