4.1.1 Flashcards
What are the four types of pathogen?
- Bacteria
- viruses
- protoctista (Protista)
- Fungi
Which type of bacteria causes communicable diseases?
Pathogens
What are the two ways that bacteria can be classified?
- Basic shapes
- cell walls
How can bacteria be classified by their basic shape?
- Rod shaped (bacilli)
- spherical (cocci)
- comma shaped (vibrios)
- spiralled (spirilla)
- corkscrew (spirochaetes)
How can bacteria be identified by their cell walls?
Two types:
- gram-positive bacteria: blue/purple under light microscope (Staphylococcus aureus MRSA)
- gram-negative bacteria: red (e.coli)
Why is knowing the type of cell wall of a bacteria useful?
Because it affects how bacteria reacts to different antibiotics
What is an antibiotic?
Compound that kills or inhibits the growth of bacteria
What is a virus? What is the structure of the virus?
- Nonliving infectious agents
- some genetic material surrounded by protein
How do viruses cause communicable diseases?
Invade living cells
Take over biochemistry of the host cell to make more viruses
Reproduce rapidly and evolve by developing adaptations to the host (successful pathogens)
What are the viruses that attack bacteria?
Bacteriophages
They take over bacterial cells and use them to replicate whilst destroying the bacteria
What is protoctista?
Eukaryotic organisms with a wide variety of feeding methods
What do protoctista cause?
Parasitic diseases that use people/animals as a host
May need a vector to transfer them to the host
What is fungi?
Eukaryotic organisms that are mostly multicellular
What do fungi do to an organism?
-They feed on dead or decaying matter but some are parasitic so can feed on living organisms
How can fungi kill a plant?
Often infect plant leaves, stopping them from photosynthesising, quickly killing the plant
How can fungi spread between organisms?
They produce millions of tiny spores that can spread Widely through crop plants
Can cause hardship and starvation
How do viruses take over? 6 steps
- Virus attaches to host cell
- It inserts viral nucleic acid (Genetic material)
- The viral nucleic acid replicates
- The synthesis of the viral protein happens
- Then the assembly of the virus particles
- Lysis of the host cell, allowing the new viruses to spread to infect other cells
How do protoctista take over a cell?
They digest and use the cells contents to reproduce
What can bacteria produce and what does this do?
Toxins (poison/damage host cells) -breakdown cell membranes -Damage/inactivates enzymes -interfere with host so genetic material Toxins or a byproduct of the normal functioning of the bacteria
How do plant diseases threaten people?
When crops fail…
- people can starve
- economies can struggle
- ecosystems are threatened as well
What is ring rot?
Bacterial disease
(potatoes tomatoes aubergines)
Damages leaves, tubers, fruit and can destroy up to 80% of the crop
No cure
What is tobacco mosaic virus?
Infects tobacco plants and around 150 other species
Damages leaves, flowers, fruit (Stunts growth, reducing yield)
No cure
There are resistant crop strains
What is potato blight?
Fungus-like protoctista
Penetrates host cells, destroys leaves/tubers/fruits
No cure
There are resistant strains
(Careful management, chemical treatments can reduce infection risk)
What is black Sigatoka?
Fungus
Attacks and destroys leaves
Fungicide treatments can control the spread
No Cure
What is tuberculosis?
Bacterial disease
Destroys lung tissue and suppresses the immune system (body is less able to fight off other diseases)
Curable with antibiotics
Preventable with a vaccination and improving living standards
What is bacterial meningitis?
Starts at brain and can spread to the rest of the body causing septicaemia
Antibiotics can cure it if delivered early
Vaccines can protect against some forms of bacterial meningitis
What is HIV/AIDS?
AIDS is caused by HIV, targets T-helper cells in the immune system so it’s gradually destroys it
People with HIV are more likely to get other infections (TB) and some types of cancer
It has the enzyme reverse transcriptase that transcribes RNA to single strand of DNA to produce a single strand of DNA in host cell.
Passed by bodily fluids
Anti retroviral drugs slow the progress of the disease
What is influenza?
Virus
Kills the ciliated epithelium cells in the gas exchange system (airway open to secondary infection)
Most deaths off from the secondary bacterial infection (pneumonia)
Having flu one year leaves you with some immunity for the next but it mutates regularly
What is malaria?
Protoctista Has two hosts: Mosquitoes and people Invades red blood cells, liver, brain making people weak and vulnerable to other infections No vaccine and limited cures Control the vector (prevent mosquitoes)
What is Ring worm?
Fungus
Causes grey white crusty infectious circular area of skin (itchy)
Antifungal cream can cure it
What is athletes foot?
Fungal disease
Grows on and Digests warm moist skin between toes
Crackling and scaling (itchy)
Antifungal cream can cure it
What are five different ways of direct Transmission?
- Kissing or contact with bodily fluids
- skin to skin contact
- microorganisms from faeces transmitted on hands
- Inoculation
- ingestion
How does transmission through inoculation happen?
-Break in the skin
– animal bites
– puncture wound or through sharing needles
How does transmission through ingestion happen?
- Consuming contaminated food or drink
- transferring pathogens from hand to mouth
What are three ways of indirect transmission?
- Formites
- droplet infection (inhalation)
- vectors
What are formites and how do they transmit diseases?
-Inanimate objects that can transfer pathogens
How does droplet infection transmit diseases?
Small droplets of saliva and mucus are expelled they can contain pathogens
Healthy individual may breathe them in and become infected
How do vectors transmit diseases?
From one house to another
Are often animals (e.g. mosquitoes)
Water can also act as a vector (e.g. diarrhoeal diseases)
People can be vectors for animal diseases (foot and mouth disease)
What is environmental factors can cause the transmission of communicable disease in animals? Mention 7
- Overcrowded living/working conditions
- poor nutrition
- compromised immune system/immunosuppressant drugs after transplant
- poor disposal of waste
- climate change (new vectors and new diseases), (high temperatures promote spread of malaria)
- culture and infrastructure (traditional medical practices)
- Socio- economic factors (lack of trained health workers, insufficient public warning during outbreak)
How does direct transmission happen between plants?
Healthy plant with any part of the disease plant
e.g. ring rot, tobacco mosaic virus, tomato and potato blight, black sigatoka
What are two ways of indirect transmission in plants?
- Soil contamination
- vectors
How does soil contamination cause indirect transmission of communicable diseases?
Infected plants leave pathogens or reproductive spores in the soil that can infect the next crop
What are the four types of vectors and how do they cause indirect transmission of communicable diseases in plants?
- wind: spores may be carried
- Water: spores swim in surface film of water on leaves
- animals: carry Pathogens and spores from one plant to another as they feed
- humans: pathogens and spores transmitted by hand, clothing,formites
What environmental factors affect the transmission of communicable diseases in plants? Name 5
- Planting variety of crops susceptible to disease
- overcrowding increases spread
- poor mineral nutrition reduce resistance
- damp and warm conditions increase survival
- climate change (allow animal vectors to spread) (increased rainfall and went to promote spread)
How do plants respond to an attack (vaguely)?
Chemical is produced when the cell wall is attacked
Release of signalling molecules
Triggers cellular responses (defensive chemicals)
These chemicals send alarm signals to unaffected cells to trigger the defences and physically strengthens the cell wall
What polysaccharide is produced when a plant recognises an attack?
Callose
What is the role of callose in plant defence?
- It is deposited between cell walls and cell membrane next to infected cells, they act as barriers preventing the pathogens from entering
- large amounts continue to be deposited after initial infection, lignin is added making the mechanical barrier thicker and stronger
Where is callose deposited and what does this do?
- Blocks sieve plates in flooring: sealing infected part, preventing spread
- Deposited in plasma does matter between infected cells and neighbours sealing them off from healthy cells to prevent spread
What is chemical defences can be used to prevent the spread of communicable diseases in plant?
- Insect repellent
- insecticides
- anti bacterial compounds (antibiotics) phenols
- Antifungal compounds (interfere with fungal cell membranes (chitinases -breaks down chitin in fungal wall)
- Anti-oomycetes (glucanases-Breakdown glucans (polymers found in cell walls of oomycetes)
- General toxins (made by plants)
How does skin keep pathogens out?
- Covers body preventing entry
- skin flora of healthy microorganisms: outcompete pathogens for space on surface
- sebum oily substance that inhibits the growth of pathogen
What adaptation in the airways keeps pathogens out?
Mucous membranes that secrete mucus (traps microorganisms, contains lysozymes)
Mucus has phagocytes that remove remaining pathogens
What do lysozymes do and where else can they be found?
Destroy bacterial and fungal cell walls
Tears and urine
What are expulsive reflexes and how do they keep pathogens out?
Coughs/sneezes eject pathogen leading mucus
Vomiting/diarrhoea expel contents of gut along with infective pathogens
How does blood clot?
Platelets come into contact with collagen and skin/wall of the damaged blood vessel and they secrete several substances
What substances do platelets secrete to help with blood clot?
Thromboplastin: enzyme that triggers a cascade of reactions resulting in the formation of blood clot
Serotonin: make smooth-muscle in the walls of blood vessels contract (reducing supply of blood to the area)
What happens after the clutch dries out and formed a tough scab?
Epidermal cells start to grow under the scab sealing the wound permanently,
Damaged blood vessels regrow
Collagen fibres are deposited to give new tissue strength
Once the new epidermis reaches normal thickness, scab falls off and the wound is healed
How is inflammation characterised?
Pain
Heat
Redness
Swelling
Describe the inflammatory response?
Mast cells are activated in damaged tissue, they release chemicals: histamines, cytokines
Histamines: make blood vessels dilate (localised heat and redness) raised temperature prevents pathogens reproducing
They also make blood vessels more leaky so blood plasma is forced out this tissue fluid causes swelling (oedema) and pain
Cytokines: attracts white blood cells that carry out phagocytosis
What are non-specific defences give two examples (animals)?
Fever
Phagocytosis
How does fever get rid of pathogens?
Cytokine stimulates hypothalamus to reset thermostat (temperature increases)
- Pathogens reproduce best at or below 37°C, high temps inhibit reproduction
- specific immune system works faster at higher temperatures
What are Phagocytes? and what are the two main types?
Specialised white cells that engulf and destroy pathogens
Neutrophils, macrophages
Describe the five stages of phagocytosis
- Pathogen is produce chemicals that attracts phagocytes
- Phagocytes recognises nonhuman proteins on pathogen (antigen) the response is not specific it’s simply to a cell or an organism that is non-self
- Phagocyte engulfs the pathogen and encloses it in a vacuole: phagosome
- phagosome combines with lysosome: phagolysosome
- Enzymes from the lysosome digest and destroy the pathogen
Why do macrophages take longer to destroy bacteria?
It’s combines antigens from the pathogen surface membrane with special glycoproteins in the cytoplasm called major histocompatibility complex (MHC)
MHC complex moves pathogen antigens to macrophages surface membrane: antigen-presenting cell
What can the antigen-presenting cell do?
Stimulate other cells involved in the specific immune system response
What are the three functions of cytokines?
Act as cell signalling molecules
Increased body temperature
Stimulate the specific immune system
What are opsonins?
Chemicals that bind to pathogens and “Tag “them so they can be more easily recognised by phagocytes
What happens during inflammation?
Mast cells are activated
What two chemicals do mast cells release? What do each of these chemicals do?
Histamines:
-dilates blood vessels (local heat and redness: slows pathogen reproduction)
-more leaky blood vessels (Swelling and pain:more tissue fluid so more neutrophils leave due to lobed nucleus)
Cytokines: cell signalling, attract phagocytes leading to phagocytosis
What is the difference between a neutrophil and a macrophage?
N: lobed nucleus, can leave the blood stream
M: round nucleus, can’t leave blood stream, has major histocompatibility complex
What is MHC responsible for?
It is the protein that turns the macrophage into an antigen presenting cell
What are the steps of a macrophage becoming an antigen presenting cell?
- macrophage engulfs pathogen
- phagosome is formed
- Phagosome fuses with lysosome making a phagolysosome, Lysosome digests the pathogen except for the antigens
- antigen and MHC combine, placed on the surface making APC
What is the difference between T lymphocytes and B lymphocytes?
T: made in bone marrow, mature in thalamus gland
B: made and matured in bone marrow (can become APC)
How is the T-helper cell activated?
CD4 Receptor recognises the antigen MHC complex
What does the T-helper cell do?
- Releases interleukins that trigger mitosis and specialisation of cells
- signals B cells to work
After mitosis of T-helper cells what can be produced?
- T memory cells
- T killer cells
- T regulatory cells
What do you T killer cells do?
Release perforin or H202 (Hydrogen peroxide)
They kill cells
What T regulatory cells do?
Suppresses immune system by killing all white blood cells except for T memory and B memory.
To prevent autoimmunity
Describe the humoural response
- Clonal selection: choosing the right B-cell (B-effector cells make different antibodies) that is complimentary to the pathogen
- Clonal expansion where the B antigen-presenting cells divide by mitosis to make B memory cells or B plasma cells
What do you B plasma cells do?
They produce many antibodies
What are the four things that immunoglobin can become?
- They can directly attack
- agglutinins
- opsonins
- antitoxins
What do agglutinins do?
They glue in different pathogen is making a big batch
Easier to catch
What do antitoxins do?
Neutralise toxins released by pathogens
What do you T memory and B memory cells do
Immunological memory
Used in the secondary response so that if encountering the same pathogen is it can go straight to specific response
What happens during inflammation?
Mast cells are activated
What two chemicals do mast cells release? What do each of these chemicals do?
Histamines:
-dilates blood vessels (local heat and redness: slows pathogen reproduction)
-more leaky blood vessels (Swelling and pain:more tissue fluid so more neutrophils leave due to lobed nucleus)
Cytokines: cell signalling, attract phagocytes leading to phagocytosis
What is the difference between a neutrophil and a macrophage?
N: lobed nucleus, can leave the blood stream
M: round nucleus, can’t leave blood stream, has major histocompatibility complex
What is MHC responsible for?
It is the protein that turns the macrophage into an antigen presenting cell
What are the steps of a macrophage becoming an antigen presenting cell?
- macrophage engulfs pathogen
- phagosome is formed
- Phagosome fuses with lysosome making a phagolysosome, Lysosome digests the pathogen except for the antigens
- antigen and MHC combine, placed on the surface making APC
What is the difference between T lymphocytes and B lymphocytes?
T: made in bone marrow, mature in thalamus gland
B: made and matured in bone marrow (can become APC)
How is the T-helper cell activated?
CD4 Receptor recognises the antigen MHC complex
What does the T-helper cell do?
- Releases interleukins that trigger mitosis and specialisation of cells
- signals B cells to work
After mitosis of T-helper cells what can be produced?
- T memory cells
- T killer cells
- T regulatory cells
What do you T killer cells do?
Release perforin or H202 (Hydrogen peroxide)
They kill cells
What T regulatory cells do?
Suppresses immune system by killing all white blood cells except for T memory and B memory.
To prevent autoimmunity
Describe the humoural response
- Clonal selection: choosing the right B-cell (B-effector cells make different antibodies) that is complimentary to the pathogen
- Clonal expansion where the B antigen-presenting cells divide by mitosis to make B memory cells or B plasma cells
What do you B plasma cells do?
They produce many antibodies
What are the four things that immunoglobin can become?
- They can directly attack
- agglutinins
- opsonins
- antitoxins
What do agglutinins do?
They glue in different pathogen is making a big batch
Easier to catch
What do antitoxins do?
Neutralise toxins released by pathogens
What do you T memory and B memory cells do
Immunological memory
Used in the secondary response so that if encountering the same pathogen is it can go straight to specific response
What happens during inflammation?
Mast cells are activated
What two chemicals do mast cells release? What do each of these chemicals do?
Histamines:
-dilates blood vessels (local heat and redness: slows pathogen reproduction)
-more leaky blood vessels (Swelling and pain:more tissue fluid so more neutrophils leave due to lobed nucleus)
Cytokines: cell signalling, attract phagocytes leading to phagocytosis
What is the difference between a neutrophil and a macrophage?
N: lobed nucleus, can leave the blood stream
M: round nucleus, can’t leave blood stream, has major histocompatibility complex
What is MHC responsible for?
It is the protein that turns the macrophage into an antigen presenting cell
What are the steps of a macrophage becoming an antigen presenting cell?
- macrophage engulfs pathogen
- phagosome is formed
- Phagosome fuses with lysosome making a phagolysosome, Lysosome digests the pathogen except for the antigens
- antigen and MHC combine, placed on the surface making APC
What is the difference between T lymphocytes and B lymphocytes?
T: made in bone marrow, mature in thalamus gland
B: made and matured in bone marrow (can become APC)
How is the T-helper cell activated?
CD4 Receptor recognises the antigen MHC complex
What does the T-helper cell do?
- Releases interleukins that trigger mitosis and specialisation of cells
- signals B cells to work
After mitosis of T-helper cells what can be produced?
- T memory cells
- T killer cells
- T regulatory cells
What do you T killer cells do?
Release perforin or H202 (Hydrogen peroxide)
They kill cells
What T regulatory cells do?
Suppresses immune system by killing all white blood cells except for T memory and B memory.
To prevent autoimmunity
Describe the humoural response
- Clonal selection: choosing the right B-cell (B-effector cells make different antibodies) that is complimentary to the pathogen
- Clonal expansion where the B antigen-presenting cells divide by mitosis to make B memory cells or B plasma cells
What do you B plasma cells do?
They produce many antibodies
What are the four things that immunoglobin can become?
- They can directly attack
- agglutinins
- opsonins
- antitoxins
What do agglutinins do?
They glue in different pathogen is making a big batch
Easier to catch
What do antitoxins do?
Neutralise toxins released by pathogens
What do you T memory and B memory cells do
Immunological memory
Used in the secondary response so that if encountering the same pathogen is it can go straight to specific response
What happens during inflammation?
Mast cells are activated
What two chemicals do mast cells release? What do each of these chemicals do?
Histamines:
-dilates blood vessels (local heat and redness: slows pathogen reproduction)
-more leaky blood vessels (Swelling and pain:more tissue fluid so more neutrophils leave due to lobed nucleus)
Cytokines: cell signalling, attract phagocytes leading to phagocytosis
What is the difference between a neutrophil and a macrophage?
N: lobed nucleus, can leave the blood stream
M: round nucleus, can’t leave blood stream, has major histocompatibility complex
What is MHC responsible for?
It is the protein that turns the macrophage into an antigen presenting cell
What are the steps of a macrophage becoming an antigen presenting cell?
- macrophage engulfs pathogen
- phagosome is formed
- Phagosome fuses with lysosome making a phagolysosome, Lysosome digests the pathogen except for the antigens
- antigen and MHC combine, placed on the surface making APC
What is the difference between T lymphocytes and B lymphocytes?
T: made in bone marrow, mature in thalamus gland
B: made and matured in bone marrow (can become APC)
How is the T-helper cell activated?
CD4 Receptor recognises the antigen MHC complex
What does the T-helper cell do?
- Releases interleukins that trigger mitosis and specialisation of cells
- signals B cells to work
After mitosis of T-helper cells what can be produced?
- T memory cells
- T killer cells
- T regulatory cells
What do you T killer cells do?
Release perforin or H202 (Hydrogen peroxide)
They kill cells
What T regulatory cells do?
Suppresses immune system by killing all white blood cells except for T memory and B memory.
To prevent autoimmunity
Describe the humoural response
- Clonal selection: choosing the right B-cell (B-effector cells make different antibodies) that is complimentary to the pathogen
- Clonal expansion where the B antigen-presenting cells divide by mitosis to make B memory cells or B plasma cells
What do you B plasma cells do?
They produce many antibodies
What are the four things that immunoglobin can become?
- They can directly attack
- agglutinins
- opsonins
- antitoxins
What do agglutinins do?
They glue in different pathogen is making a big batch
Easier to catch
What do antitoxins do?
Neutralise toxins released by pathogens
What do you T memory and B memory cells do
Immunological memory
Used in the secondary response so that if encountering the same pathogen is it can go straight to specific response
What happens during inflammation?
Mast cells are activated
What two chemicals do mast cells release? What do each of these chemicals do?
Histamines:
-dilates blood vessels (local heat and redness: slows pathogen reproduction)
-more leaky blood vessels (Swelling and pain:more tissue fluid so more neutrophils leave due to lobed nucleus)
Cytokines: cell signalling, attract phagocytes leading to phagocytosis
What is the difference between a neutrophil and a macrophage?
N: lobed nucleus, can leave the blood stream
M: round nucleus, can’t leave blood stream, has major histocompatibility complex
What is MHC responsible for?
It is the protein that turns the macrophage into an antigen presenting cell
What are the steps of a macrophage becoming an antigen presenting cell?
- macrophage engulfs pathogen
- phagosome is formed
- Phagosome fuses with lysosome making a phagolysosome, Lysosome digests the pathogen except for the antigens
- antigen and MHC combine, placed on the surface making APC
What is the difference between T lymphocytes and B lymphocytes?
T: made in bone marrow, mature in thalamus gland
B: made and matured in bone marrow (can become APC)
How is the T-helper cell activated?
CD4 Receptor recognises the antigen MHC complex
What does the T-helper cell do?
- Releases interleukins that trigger mitosis and specialisation of cells
- signals B cells to work
After mitosis of T-helper cells what can be produced?
- T memory cells
- T killer cells
- T regulatory cells
What do you T killer cells do?
Release perforin or H202 (Hydrogen peroxide)
They kill cells
What T regulatory cells do?
Suppresses immune system by killing all white blood cells except for T memory and B memory.
To prevent autoimmunity
Describe the humoural response
- Clonal selection: choosing the right B-cell (B-effector cells make different antibodies) that is complimentary to the pathogen
- Clonal expansion where the B antigen-presenting cells divide by mitosis to make B memory cells or B plasma cells
What do you B plasma cells do?
They produce many antibodies
What are the four things that immunoglobin can become?
- They can directly attack
- agglutinins
- opsonins
- antitoxins
What do agglutinins do?
They glue in different pathogen is making a big batch
Easier to catch
What do antitoxins do?
Neutralise toxins released by pathogens
What do you T memory and B memory cells do
Immunological memory
Used in the secondary response so that if encountering the same pathogen is it can go straight to specific response
What happens during inflammation?
Mast cells are activated
What two chemicals do mast cells release? What do each of these chemicals do?
Histamines:
-dilates blood vessels (local heat and redness: slows pathogen reproduction)
-more leaky blood vessels (Swelling and pain:more tissue fluid so more neutrophils leave due to lobed nucleus)
Cytokines: cell signalling, attract phagocytes leading to phagocytosis
What is the difference between a neutrophil and a macrophage?
N: lobed nucleus, can leave the blood stream
M: round nucleus, can’t leave blood stream, has major histocompatibility complex
What is MHC responsible for?
It is the protein that turns the macrophage into an antigen presenting cell
What are the steps of a macrophage becoming an antigen presenting cell?
- macrophage engulfs pathogen
- phagosome is formed
- Phagosome fuses with lysosome making a phagolysosome, Lysosome digests the pathogen except for the antigens
- antigen and MHC combine, placed on the surface making APC
What is the difference between T lymphocytes and B lymphocytes?
T: made in bone marrow, mature in thalamus gland
B: made and matured in bone marrow (can become APC)
How is the T-helper cell activated?
CD4 Receptor recognises the antigen MHC complex
What does the T-helper cell do?
- Releases interleukins that trigger mitosis and specialisation of cells
- signals B cells to work
After mitosis of T-helper cells what can be produced?
- T memory cells
- T killer cells
- T regulatory cells
What do you T killer cells do?
Release perforin or H202 (Hydrogen peroxide)
They kill cells
What T regulatory cells do?
Suppresses immune system by killing all white blood cells except for T memory and B memory.
To prevent autoimmunity
