4.1 Flashcards
Pathogen
A microorganism that causes disease
Direct transmission
Passing a pathogen from host to host with no intermediary
Indirect transmission
Passing a pathogen from host to new host via a vector
Transmission
Passing a pathogen from an infected individual to an uninfected individual
Vector
An organism that carries a pathogen from one host to another
Callose
A large polysaccharide deposit that blocks old phloem sieve tubes
Inflammation
Swelling and redness of tissue cause by infection
Mucous membrane
Specialised epithelial tissue that is covered in mucus
Primary defence
Those that prevent pathogens entering the body
Antigen presenting cell
Cell that isolated the antigen form a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system
Clonal selection
Selection of a specific B or T cell that is specific to the antigen
Cytokines
Hormone like molecules used in cell signalling to stimulate the immune response
Neutrophils
A type of white blood cell that engulfs foreign matter and traps it in a large phagosome which fuses with lysosomes to digest the foreign matter
Opsonins
Proteins that bind to the antigen on a pathogen and then allow phagocytes to bind
Antibodies
Specific proteins released by plasma cells that can attach to pathogenic antigens
B memory cells
Cells that remain in the blood for a long time providing long term immunity
Clonal expansion
An increase in the number of cells by mitotic cell division
Interleukins
Signalling molecules that are used to communicate between different WBC
Plasma cells
Derived from the B lymphocytes, these r cells that manufacture antibodies
T helper cells
Cells that release signalling molecules to stimulate the immune response
T killer cells
Cells that attack and destroy our own body cells that are infected by a pathogen
T memory cells
Cells that remain in the blood for a long time providing long term immunity
T regulator cell
Cells that are involved with inhibiting or ending the immune response
What’s a pathogen
An organisms that causes disease
What is the organism that carries a pathogen called
A host
What is the hosts role for a pathogen
Creates a good habitat which the microorganism can live in
As a results of the host function what happens
Numerous types of microorganisms live in and on the body of another organism
How do pathogens live and what is its disadvantage
By taking nutrients from their host, but this can cause damage to the host
What kingdom does bacteria belong to
Prokaryotae
What are prokaryotae-bacteria cells like compared to eukaryotes
They are smaller but can reproduce rapidly in the right condition
In the right condition how many times can bacteria reproduce
Some can reproduce every 20mins in right condition
What happens once bacteria be enters host
They can multiply rapidly
How do bacteria presence in a host cause damage in animals
Causes disease by damaging cells or by releasing waste products/toxins harmful to the host
In plants how does bacteria cause damage
Bacteria often lives in vascular tissue and causes blackening and death of these tissues
Does fungi cause only one disease in plants and animals
Fungi causes a variety of diseases
how do fungal infections in animals work
Fungus lives in the skin of animals and where it’s hyphae which forms mycelium and grows under the skins surface
How does fungal infections spread
Fungus sends out special reproductive hyphae which grows to the surface on the skin to release spores causing redness and irritation
How to fungal infections spread in plants
Fungus often lives in vascular tissue where it gains nutrients, hyphae then releases extracellular enzymes like cellulase, to digest surrounding tissue which causes decay
What are symptoms of fungal infections in plants
Leaves often become mottled in colour (curled up and shrivelled) before dying, fruit storage organs like tubers (potatoes) will turn black and decay
How do viruses cause damage
They invade cells and take over genetic machinery and other organelles of a cell, they then cause the cells to manufacture more copies of the virus and host cells eventually burst which releases many new viruses which can infect healthy cells
What are protoctista
Diseases caused by animals like protoctists
How do protoctista cause harm to host
By entering host cells and feeding on the contents as they grow
How to the protoctista malaria cause harm
Malaria parasite (plasmodium) has immature forms that feed on haemoglobin inside RBC
What are the characteristics of tuberculosis
Affects many parts of the body, kills cells and tissues and lungs are usually attacked
What are symptoms of tuberculosis
Long lasting cough, weight loss, fever, night sweats
What organism causes disease tuberculosis and how do you cure it
Bacteria, treated by antibiotics for several months
What are characteristics of bacterial meningitis
Infections of meninges(membrane that surrounds brain and spinal cord), if membrane swells it causes damage to brain and nerves
What organism causes bacterial meningitis and how is it cured
Bacteria and cured by antibiotics
What are characteristics of ring rot (in plants)
Rings of decay in vascular tissue of a potato tuber or tomato as well as wilting of leaves
What organism causes ring rot and how do you treat it
Bacterium and remove infected plants
What are at or tons of bacterial meningitis
Seizures, headaches, drowsy, fever
What are symptoms of ring rot
Vascular wilt
What are characteristics of HIV/AIDS
Attacks cells in immune system and compromises immune response
What are symptoms of HIV/AIDS
Fever, rash, swollen glands
What organism causes HIV/ AIDS and how is it treated
Virus and can’t be treated but can live with it if you take antiretroviral drugs
What are characteristics influenza
Attacks respiratory system and causes muscle pain and headaches
What organism causes influenza and how is it cured
Virus and fluids and painkillers cure it
What are characteristics of tobacco mosaic virus
Causes mottling and discoloured leaves
What organism causes tobacco mosaic virus and how is it cured
Virus and cured by removing infected plants
What are characteristics of black Sigatoka (banana plants)
Causes leaf spots on banana plant, reducing yield
What organism causes black Sigatoka and how is it cured
Fungus and remove infected leaves and neighbouring leaves
What is characteristics of blight (tomato and potato)
Affects leaves and potato tuber and causes watery rot on leaves
What organism causes blight and how is it cured
Protocistan and removed infected ones and spray others with fungicide
What are characteristics of ringworm (cattle)
Growth of fungus in skin with spores causing erupting through skin to cause rash
What organism causes ringworm and how is it cured
Fungus and anti fungal cream
What are characteristics of athletes foot
Growth under the skin of feet, especially between toes
What organism causes athletes foot and how is it cured
Fungus and anti fungal cream
What are characteristics of malaria
Parasite in blood that causes headaches and fevers and may progress to coma and death
What organism causes malaria and how is it cured
Protoctistan and hard to treat
What happens after plants manufacture sugars in photosynthesis
They convert them to a wide variety of compounds like proteins and oils
What does sugars converting into proteins and oils in a plant mean for other organisms
They are a rich source of nutrients for many organisms like bacteria, fungi, protoctists, viruses, insects and vertebrates
Why is it bad for the plant that many organisms want to feed of them
Bacteria, fungi, protoctists and viruses may be pathogenic and insects and vertebrates may be vectors to help transmit these pathogens
Do plants have an immune system
They don’t have one like humans but they have developed a wide range of structural and chemical and protein based defences which can detect invading organisms and prevent them from causing extensive damage
What do plant defences include
Passive defences to prevent entry and active defences which are introduced when a pathogen detected
What is a passive defence in plants
Defences present before infection, their role is preventing entry and spread of pathogen, including physical and chemical barriers
What is the biggest physical and passive defence
Cellulose cell wall, acts as a physical barrier and contains a variety of chemical defences too activate when pathogen detected
How is lignin thickening of cell walls a little physical and passive defence
Lignin is waterproof and almost completely indigestible so pathogen will find it hard to enter it
How are waxy cuticles a passive and physical defence
They prevent water from collecting on cells surface, since pathogens collect in water and need water to survive lack of water is a passive defence
How is bark a passive and physical defence
Contains a variety of chemical defences that work against pathogenic organisms
How is stomata closure a physical and passive defence
Stomata are point of entry for pathogens, stomatal opening controlled by guard cells, when pathogenic organism detected, guard cells will close the stomata at that part of the plant
How is callose a physical and passive defence
It’s a large polysaccharide that is deposited in sieve tubes at the end of growing season, it’s deposited around sieve plates and blocks flow in sieve tubes which prevents pathogens spreading round the plant
How is tylose formation a passive and physical defence
Balloon like swellings or projections that fill xylem vessel, when tylose fully formed it plugs the vessel and vessel can no longer carry water, blocking xylem prevents spread of pathogens through heartwood (tylose also has high concentration of chemicals like terpenses-harmful to pathogens
What are some chemical defences plants have
Plant tissue contains variety of chemicals that have anti-pathogenic properties including terpenoids, phenols, alkaloids, hydrolytic enzymes
What chemical defences are passive (present before infection)
Terpenes and tylose and tannis in bark
Why are most chemicals not produced until plant detects infection
As they require lots of energy
What are active defences in plants
When pathogen attacks, specific chemicals in their cell wall can be detected by plant cells, these chemicals include specific proteins and glycolipids, plant responds by forfeiting defences already present which includes increasing physical defences and producing defensive chemicals
How can cell wall become an active defence
When pathogen detected cell wall thickens and strengthens with additional cellulose
How can deposition of callose become a active defence
Deposition of callose between plant cell wall and cell membrane near invading pathogen, callose deposits are polysaccharide polymers that impede cellular penetration at site of infection, it strengthens cell walls and blocks plasmodesmata
How are oxidative bursts a active defence
Oxidative bursts that produce highly reactive oxygen molecules capable of damaging the cells of invading organisms
What defence is an increase in production of chemicals
Active defence
What is the action of the active chemical defence terpenoids
Range of essential oils that have antibacterial and antifungal properties, may also create a scent like methanols and menthones produced by mint plant
What is the action of the active chemical defence phenols
Have antibiotic and antifungal properties. Tannis in bark inhibits attack by insects, these compounds bind to salivary proteins and digestive enzymes like trypsin and chymoteyspin, deactivating the enzymes. Insects that ingest high amounts of tannis don’t grow and die which helps prevent transmission of pathogens
What is the action of the active chemical defence alkaloids
Nitrogen-containing compounds like caffine, nicotine, cocaine, morphine, solanine. They give a bitter taste to inhibit herbivores feeding. They also act in a variety of metabolic reactions via inhibiting/activating enzyme action. Some alkaloids inhibit protein synthesis, if plant can reduce grazing by larger animals, it suffers less damage which can allow pathogens to enter plant
What is the action of the active chemical defence defensins (defensive proteins)
Small cysteine-rich proteins which broad anti-microbial activity, they appear to act upon molecules in plasma membrane of pathogens, possibly inhibiting action of ion transport channels
What is the action of the active chemical defence hydrolytic enzymes
Found in spaces between cells, include chicinease which breaks down chichin in fugal cell walls, glucanases which hydrolyse glycosidic bonds in glucans and lysosomes which are capable of degrading bacteria cells
What is necrosis
Deliberate cell suicide. A few cells sacrificed to save rest of the plant. By killing cells surrounding infection, the plant can limit pathogens access to water and nutrients, stopping it spread further around the plant
How is necrosis brought about by intracellular enzymes activated
By injury, these enzymes destroy damaged cells and produce brown spots on leaves or dieback
What is canker
Sunken necrotic lesion in the woody tissue like main stem or branch which causes death of cambium tissue in bark
How does plant defence overall work
Pathogen detected by plant cell wall receptors in cell membrane as when pathogen breaks down cell wall their bi-products recognised. So, a signalling molecule alerts nucleus of attack. Callose and lignin are then made to strengthen cell wall and defensive chemicals warn other cells before they’re attacked. Some defence molecules even directly attack the pathogen
What does pathogens life cycle involve
Living in or on other living things
What is the bi-product of a pathogens life cycle
It causes harm to their host
What does the pathogens life cycle involve in stages
Travelling from one host to another (transmission), entering the hosts tissue, reproducing and leaving hosts tissue
How are most pathogens transmitted
Pathogenic organisms can be transmitted between animals in many ways but most common is direct transmission
What is one method of direct transmission
Direct physical contact, like touching a person whose infected or touching contaminated surface or soil that harbours pathogens such as HIV, meningitis, ringworm and athletes foot
What factors effect direct transmission by direct physical contact
Hygiene-washing hand regularly, keeping surfaces clean, disinfecting cuts or abrasions, sterilising surgical instruments, using condoms during sexual intercourse
What is another way direct transmission can happen (faecal)
Faecal-oral transmission usually by eating food or drinking water contaminated by the pathogen like cholera and food poisoning
What factors effect direct transmission via faecal
Using human sewage to fertilise crops is common in some parts of the world, treatment of waste water And drinking water are important way to reduce risk. Washing all fresh food using treated water m, careful food prep and making sure food isn’t raw all reduce risk
What is another means of direct transmission (droplet)
Droplet infection-in which pathogens carried in tiny water droplets in the air like TB and influenza
What factors effect direct transmission by droplet infection
Catch it-bin it-kill it, cover mouth when coughing or sneezing, use a tissue and dispose of the tissue correctly
What is a means of direct transmission (spores)
Transmission by spores, which are a resistant stage of the pathogen. Can be carried by air or residue on surfaces or in soil like anthrax or tetanus
What factors effect direct transmission via spores
Use of mask and washing skin after contact with soil
What are 4 main ways of direct transmission
Direct physical contact, faecal contact, droplet infection, transmission by spores
What social factors also effect transmission (6)
Over-crowding(lots of people living in a house), poor ventilation, poor health (immunocompromised), poor diet, homelessness, living/working with people who have migrated from places where disease is more common
What is indirect transmission
Some pathogens are transmitted indirectly via a vector
What is a vector and give an example
Another organism that may be used by the pathogen to gain entry to primary host such as plasmodium parasite that causes malaria enters human host by bite from female mosquitoes
What is the life cycle of plasmodium (uses vector)
Person with malaria->gametes of plasmodium in blood->female mosquito sucks blood->plasmodium develops and migrated to mosquito salivary glands->uninfected person bitten->plasmodium migrates to liver->plasmodium migrates to blood-> person with malaria
How to plant pathogens spread
Also by direct and indirect means
How may pathogens in soil enter the plant
Will infect plants by entering the roots, especially if they have been damaged as a result of replant, burrowing animals or movement by storm
How does airborne transmission work in plants
Many fungi produce spores as a means of sexual or asexual reproduction, these spores are then carried by the wind and once pathogen inside plant in may affect vascular tissue
How may pathogens on leaves enter plant
Pathogens on leaves are distributed when leaves shed in autumn and carry pathogens back to soil where it can grow and infect other plants
How can pathogen effect plant when they enter the fruit and seed
Pathogen enters fruit or seed and is then distributed within seeds so many/all offspring are infected
How does indirect transmission in plants often occur
As a result of an insect attack
How do spores and bacteria enter plant by indirect transmission
Spores and bacteria become attached to burrowing insects which attack infected plant, when that nettle attacks another plant, pathogen is transmitted to uninfected plant so beetle acts as a vector
Give an example of indirect transmission in plants
Fungus that causes Dutch elms disease is carried by a beetle
What can many pathogens do in warm and moist conditions
Many protoctists, bacteria and fungi can grow and reproduce mor rapidly in warm and moist conditions so they tend to be more common in warmer climates
What happens to pathogens in cool climates
Pathogens which live in warm climates may become damaged or even killed by winter weather as it reduces their ability to grow and reproduce
What does it mean as pathogens thrive in warmer climates
Their is a greater variety or diseases to be found in warmer climates and animals or plants living in these regions are more likely to become infected
What do pathogenic organisms need to do before causing harm
Enter the hosts body
What has evolution done to hosts to make it harder for pathogenic organisms to enter the body
Evolution has adapted hosts to defend themselves against invasion
What are primary defences
Mechanisms that have evolved to prevent entry of pathogenic organism, they are non-specific as they prevent entry of any pathogen
What kind of defence is skin
Primary defence
How is skin the main primary defence
Body covered by skin, outer layer of skin called epidermis and consists of layer of cells
What are most of the cells in epidermis called
Keratinocytes
What are keratinocytes
These are cells produced by mitosis at base of epidermis and then migrate out to surface of the skin
What happen as keratinocytes migrate out to surface of skin
They dry out and cytoplasm is replaced by protein keratin which is a process called keratinisation and takes about 30days
What happens by the time keratinocytes have reached the cells surface
They are no longer alive, keratinised layer of dead cells act as an effective barrier to pathogens and eventually dead cells slough off (dust)
Skin only protects as long as…?
It’s complete
What do abrasions and lacerations open the body to
Damaged skin opens body up to infection
What happens when we cut ourselves to prevent infection
Body must prevent excess blood loss by forming a clot, this makes a temporary seal to prevent infection and to repair skin
Why is blood clotting a complex process
As it is important to prevent clots forming in blood vessels, where they are not needed
What is involved in blood clotting
Calcium ions and atleast 12 factors known as clotting factors
Where are many clotting factors released from and what does this cause
Many clotting factors released from platelets and damaged tissue which activates an enzyme cascade
What happens once a clot
Is formed
Clot will begin to dry out and form a scab, scab shrinks as it dries, drawing sides of cut together, making a temporary seal under which skin is repaired
How is skin repaired under scab
First stage is deposition of fibrous collagen under the scab, stem cells in the epidermis then divide by mitosis to form new cells which migrate to end of cut and differentiates to form new skin, new blood vessels grow to supply oxygen and nutrients to new tissues, tissues contract to draw edges of cut together so repair can be completed, as new skin completed scab will be released
What is the disadvantage of the exchange surfaces where oxygen and nutrients have to be exchanged to enter our blood
Exchange surface must be thinner so less well protected from pathogens
What may air and food from our environment harbour and why is this a problem
May harbour microorganisms so the airway, lungs, digestive system are at risk of infection
How are the lungs, airways, digestive system protected from infection
Mucous membrane
What is a mucous membrane
Epithelial layers contain mucus secreting cells called goblet cells and their are also extra mucus-secreting glands under epithelium
How does mucus membrane work in lungs
Mucus lines passages and traps pathogens that may be in the air, epithelium also has ciliated cells, cilia are tiny hair like organelles that move mucus to top of trachea where is can enter oesophagus, it’s swallowed and passes down digestive system where pathogen is killed by stomach acid which denatures pathogens enzymes
Apart form airways, lungs where is mucous membrane also found
Gut, genital area, anus, ear, nose
What is an adaptation of areas prone to attack by pathogen
They are sensitive, they respond to irritation that may be caused by presence of microorganisms or by the toxins they release-these reflexes include coughing, sneezing and vomiting
How does coughing/sneezing protect against infection
Sudden expulsion of air will carry with it the microorganism causing the irritation
What is a sign tissue is infected
Swelling and redness known as inflammation where tissue cells hot and painful
What are mast cells
Presence of microorganisms in tissue is detected by specialised cells known as mast cells, they then release a cell signalling substance called histamine
What does histamine do to surrounding tissue
Has a range of effects on surrounding tissue, which acts to help combat infection, the main effect is to cause vasodilatation and make capillaries walls more permeable to white blood cells and some proteins
What happens once mast cells cause capillary walls to be more permeable
Blood plasma and phagocytic white blood cells leave blood and enter tissue fluid which leads to increased production of tissue fluid which causes swelling known as an oedema
What happen to excess tissue fluid after oedema formed and what does this lead to
Excess tissue fluid drained into lymphatic system where lymphocytes are stored which can lead to pathogens coming into contact with lymphocytes and initiating specific immune response
What are other less important primary defences
Eyes protected by antibodies and enzymes in tissue fluid, ear canal lined with wax to trap pathogens, female reproductive system protected by mucus plug in cervix and by maintaining relitavely acidic conditions in vagina
What are the 5 main primary non specific defences
Skin, blood clotting, mucous membrane, coughing sneezing, inflammation
What are secondary no specific defences used to combat
Pathogens that have entered the body
When pathogen enters body how is it recognised as foreign
By the chemical markers on its outer membrane, makers called antigens
What are antigens
Proteins or glycoproteins intrinsic to plasma membrane
How are pathogens antigens recognised as foreign
Antigens are specific to an organism so it’s detected as foreign. Are own cells have antigens, but they are recognised as our own and don’t produce a response
What are opsonins
Protein molecules that attach to the antigens on the surface of a pathogen-they are a type of antibody
Are all opsonins specific and what does this mean
Some aren’t very specific so can attach to a variety of pathogenic cells
What is role of opsonins
The role of opsonins is to enhance ability of phagocytic cells to bind and engulf the pathogen
What is the first line of secondary non-specific defence
Phagocytosis
What is phagocytosis
Specialised cells in blood and tissue fluid engulf and digest the pathogen
What is the most common phagocyte and how do you recognise it
Neutrophil and recognise them by their multi-lobed nucleus
Where are neutrophils manufactured
Bone marrow
Where are neutrophils found
They travel in the blood and often squeezed out of blood into tissue fluid
How long do neutrophils live and in what quantity
Short-lived but they will be released in large numbers as result of infection, die after engulfing a few pathogens
What are features of neutrophils and function
Have many lysosomes and they engulf and digest pathogens, dead neutrophils may collect in an area of infection and form pus
What are the 6 stages of phagocytosis
1.phagocytosis attracted by chemicals produced by pathogen 2.phagocyte recognises pathogen as foreign and binds to it 3.phagocyte engulfs pathogen to form a phagosome-lysosomes move to phagosome and combine forming phagolysosome 4.in phagolysosome digestive enzymes break down pathogen 5.digested pathogen absorbed by phagocyte-antigen combine with MHC in cytoplasm 6.MHC/antigen complex is displayed on phagocyte membrane, making an antigen presenting cell
What are macrophages
Larger cells manufactured in bone marrow, they travel in blood as monocytes before settling in body’s tissue
Where are many macrophages found
In lymphnodes where they mature into macrophages
What are dendritic cells and where are they found
Type of macrophage and found in more peripheral tissues
What do macrophages play an important role in
Initiating specific immune response to invading pathogens
What happens when macrophage engulfs a pathogen
It doesn’t fully digest it, the antigen from the surface is saved and moved to a special complex on the surface of the cell and it becomes an antigen-presenting cell
Why do macrophages expose the antigen on its surface
So that other cells of the immune system can recognise the antigen, the special protein complex ensures that the antigen-presenting cell isn’t mistaken for a foreign cell and attacked by other phagocytes
What do antigen presenting cells do
Move around the body where it can come into contact with specific cells that can activate the full immune response, these are T lymphocytes and B lymphocytes, there may only be one T and one B cell with the correct recognition site for the antigen, so, the role of the antigen presenting cell is to increase the chance that the antigen will come into contact with them
What is clonal selection
Activation of specific B and T cells
What does clonal selection bring to play
A complex series of events that lead to production of antibodies that can combat the specific pathogen and memory cells that will provide long term immunity
What is the whole series of specific immune response stimulated and coordinated by
Lots of hormone like chemicals called cytokines which stimulate the differentiation and activity of macrophages, B and T cells
What are secondary non specific defences
Antigens and opsonins, phagocytes, phagocytosis, macrophages
What does specific immune response involve
B lymphocytes (b cells) and T lymphocytes (t cells)
What are T and B lymphocytes
White blood cells with large nucleus and specialised receptors on their plasma membrane
What does the immune response produce and why
Antibodies as it is antibodies that neutralise foreign antigens
What does immune response provide
Long term immunity from the disease, it produces immunological memory by the release of memory cells which circulate body for many years
What 4 cell types do T lymphocytes develop into
T helper cells, T killer cells, T memory cells, T regulator cells
What is a T helper cell
Releases cytokines- chemical messengers that stimulate B cells to develop and stimulate phagocytosis phagocytes
What are T killer cells
Attack and kill host-body cells that display foreign antigens
What are T memory cells
Provide long term immunity
What are T regulator cells
Shut down immune response after pathogen has been successfully removed, so also involved in preventing autoimmunity
What are 2 cell types B lymphocytes develop into
Plasma cells and B memory cells
What are plasma cells
Circulate in the blood, manufacturing and releasing the antibodies
What are B memory cells
Remain in the body for number of years and act as immunological memory
What does specific immune response involve and what must be done to make it successful
Coordinated action of a range of cells- to work effectively they must communicate- known as cell signalling
How is communication between cells achieved
The release of hormone like chemicals called cytokines
Is their only one signalling molecule and what does this mean
There’s a huge range of signalling molecules, each performing a different role and in order to detect a signal, the target must have a cell surface receptor complementary in shape to shape of signalling molecule
What are 3 examples of communication using cytokines
Macrophages release monokines, some attract neutrophils by chemotaxis and others stimulate B cells to differentiate and release antibodies. T cells and macrophages release interleukins which stimulate clonal expansion (proliferation) and differentiation of B and T cells. Many cells can release interferon, which inhibits virus replication and stimulates activity of T killer cells
What is chrmotaxis
Movement of cells towards certain chemicals
When does autoimmune disease occur
When immune system attacks a part of the body
What are B and T cells normally specific to and what happens in case of autoimmune diseases
Normally T and B cells specific to our antigens are destroyed during early development of immune system, but autoimmune disease arises when antibodies start to attack our own antigens (possibly as antigens that aren’t usually exposed become exposed to attack)
What are causes of autoimmune diseases
Unknown but seem to include both genetic and environmental factors
What are examples of autoimmune diseases
Arthritis-painful inflammation of a joint, cause is uncertain but starts with antibodies attacking membranes around the joint. Lupus-can affect parts of the body causing swelling and pain, it may be associated with antibodies that attack certain proteins in the nucleus in cells and affected tissue
What are antigens
Molecules that can stimulate an immune response - generate antibody response
What molecules can act as an antigen
Almost any but they are usually proteins or glycoproteins in pathogens plasma membrane
What will happen to a foreign antigen in human body
It will be detected by the immune system and will stimulate the production of antibodies
What are antibodies specific to
Antibodies are specific to the antigen and antigen specific organism, so antibody specific to pathogen
Why don’t our antigens stimulate an immune response
Our antigens are recognised by our immune system so don’t usually stimulate any response
What are antibodies
Immunoglobulin- a complex protein produced by plasma cells in the immune system
When are antibodies released
They are released in response to an infection
How do antibodies work
They have a region with a complementary shape to that of particular antigen, they attach to antigens and render them harmless
How many antibodies must our immune system manufacture
One type of antibody for every antigen detected
What is antibodies structure
Y shaped with 2 distinct region, they consist of 4 polypeptide chains
What are the 2 regions on an antibody
Variable region-had a shape specific to the shape of the antigen. Constant region- is the same in all antibodies, it may have a site for the easy binding of a phagocytic cell
Detailed structure of antibody
Just underneath the variable region on Y fork is the light polypeptide chain, disulphide bridges hold polypeptides together, at the Y intersect there is a hinge region to allow flexibility so molecules can grip more than 1 antigen, bottom of Y is heavy polypeptide chain
How do most antibodies work
By attaching to antigens on pathogens
What are the 3 main groups of antigens
Opsonins, agglutinins, anti-toxins
What are opsonins
A group of antibodies that bind to antigens on a pathogen, they then act as binding sites for phagocytic cells, so they can more easily bind and destroy the pathogen
Are opsonins specific to antigens
Some opsonins aren’t very specific and stick to types of molecules that aren’t found in host cells (eg.peptidoglycan found in bacteria cell wall), others are produced as part of specific immune response and bind to very specific antigens, the pathogen may have another use of this antigen molecule (eg.it may be binding site used for attachment to host cell)
What is neutralisation in opsonins
Opsonins bind to antigen and renders them useless
What do opsonins do as well as assist in phagocytosis
Prevent the pathogen entering a host cell before it can be attacked by phagocytes
What are agglutinins
Each antibody molecule has 2 identical binding sites, it can cross link pathogens by binding an antigen on one pathogen with one binding site and an antigen on another pathogen with its other binding site
How does agglutinins destroy pathogens
When many antibodies perform the crosslinking they clump together (agglutinate) the pathogen
What are the 2 advantages of agglutinins
They agglutinated pathogens are physically impeded from carrying out some functions like entering host cells. And agglutinated pathogens are readily engulfed by phagocytes(esp effective against viruses)
What are anti-toxins
Some antibodies bind to molecules that are released by pathogenic cells, these molecules may be toxic and the action of anti-toxins renders them harmless
What happens when infecting antigens first detected
The immune system starts to produce antibodies
How long does it take for the number of antibodies in the blood to rise to a level that can successfully combat infection
A few days
What is primary immune response
When antibody levels rise enough in the blood to combat an infection, once pathogen has been dealt with the number of antibodies in the blood drops rapidly
Antibodies don’t stay in the blood but what happens if the same antigen is detected again
If body infected by same pathogen second time, antibodies must be made again but as a result of specific immune response there will be B and T memory cells circulating in the blood, these cells can recognise specific antigens and immune system can swing into action quicker, this time production of antibodies start sooner and is much faster (secondary immune response)
What is good about secondary immune response
It is usually quick enough to prevent any symptoms being detected by host
What do vaccinations provide
Provides immunity to specific diseases, this is created by deliberate exposure to antigenic material that has been rendered harmless - mostly injected but sometimes taken orally
How does immune system treat antigenic material injected from vaccine
As a real disease, so immune system activated and manufactures antibodies and memory cells to give long term immunity
What are the different forms antigenic material used in vaccines can take
Live, attenuated, dead, toxoid
How does a whole/live virus work
Usually not as harmful as the one that causes disease but very similar antigens so antibodies produced will be affective against real disease (eg. Smallpox vaccine uses similar virus-cowpox)
How does harmless/attenuated work
Weakened form of pathogenic organism such as measles and TB vaccine
What is an example of a dead pathogen vaccine
Typhoid and cholera vaccine
What is an example of vaccines where a preparation of the antigen from a pathogen
Hepatitis B vaccine
What is a toxoid vaccine
A harmless version of a toxin like tetanus vaccine
What is herd vaccination
Using vaccine to provide immunity to all/almost all of population at risk
How does herd vaccination occur
Once enough people are immune, disease can no longer be spread through population and herd immunity is achieved
What is needed for herd immunity to be effective
Almost all population must be vaccinated such as 80-85% of vaccines needed to eradicate small pox and 95% for measles
In the UK there’s a vaccination programme to immune young children against what diseases
Diphtheria, tetanus, wooping cough, polio, meningitis, measles, mumps, rubella - vaccines given to most kids at appropriate age
When is ring vaccination used
In new cases of a new disease being reported
What is ring vaccination
When you vaccinate people in immediate vicinity of the new case/ cases which may mean vaccinating surrounding households or even a whole town/village
Where is ring vaccination used worldwide
To control spread of livestock disease
What happens once disease is eradicated or at low enough Kew it won’t spread
Vaccination program can become relaxed
With what diseases has the vaccine programme relaxed
Smallpox and TB vaccine mostly stopped for UK kids
What happens when pathogen undergo genetic mutations which change their antigens
Memory cells produced by vaccination don’t recognise new antigen and so pathogen may be transmitted and incidence of disease increases
What is an example of a difficult disease to vaccinate against
Influenza as it is relatively unstable and regularly undergoes change in its antigens, when this happens epidemic may occur
Why must threats from epidemics be monitored
So new strains of pathogen can be identified which enables health authorities to prepare from impending pandemic by stockpiling suitable vaccines and vaccinating those at risk from certain disease
What is influenza and who does it affect
A killer disease cause by a virus, people over 65 and those with respiring tract conditions most at risk
What occasionally happens with influenza that causes risk of epidemic and 3 examples
A new strain of flu virus arises that’s particularly virulent such as 1918 flu epidemic killed 40million worldwide, 1968/9 1 million died from Hong Kong flu and 2009-10 540 000 cases of swine flu in UK
Ehh are worldwide numbers unknown for swine flu
Numbers unknown as strain was less virulent that expected so many cases were unreported
Why are people at risk immunised
To avoid a pandemic
What does the UK vaccination programme ensure for influenza
Over 65 and at risk are vaccinated and immunised- in 2013/14 75% over 65 immunised and 5% at risk we immunised
What is newest development on influenza vaccine
Vaccine developed which can be taken by nasal spray and proposed to be given to all children in new few years
What is so difficult about vaccinating flu
Strain of flu changes each year so immunisation programme has to change vaccine each year (worldwide research determines most likely strain)
What are the 4 different ways immunity can be achieved
Natural, artificial, active, passive
What is natural immunity
Achieved by normal life processes
What is artificial immunity
Achieved through medicinal intervention
What is active immunity
Achieved when immune system activated and makes its own antibodies
What is passive immunity
Achieved when antibodies are supplied from another source
What is active natural immunity
Immunity provided by antibodies made in immune system as result of infection, a person suffers once and then is immune like chickenpox
What is natural passive immunisation
Antibodies provided via placenta or breast milk, this makes babies immune to diseases to which mother is immune to which is useful for first year of babies life when their immune system developing
What is artificial active immunity
Immunity provided by antibodies made in immune system as result of vaccine, person injected with weakened, dead or similar pathogen or with antigens and this activates their immune system (immunity to TB or influenza)
What is artificial passive immunity
Immunity provided by injection of antibodies made by another individual (hepatitis A and B), tetanus can also be treated this way when vaccine using toxoid hasn’t worked well
How many different types of medicine are there in UK
6000
Why are new drugs needed x3
New diseases emerging, still many diseases with no effective treatment, some antibiotic treatment became less effective
How are new medicines discovered
Accidentally, observation of wildlife, plant research, personalised medicine, synthetic biology
What is a famous accidental discovery of a drug
Antibiotic penicillin discovered by Fleming
How does penicillin work
Fungus penicillin releases compounds that kill bacteria
How did Fleming discover penicillin
Accident but he observed what he saw and explained what he saw, then Florey and Chain purified penicillin and demonstrated potential use of antibodies- shows importance of teamwork in science
Are drugs a new discovery
No, many drugs have been used for centuries as people noted plants/extracts that have beneficial effect
What did world health organisation calculate that the worlds population relies on traditional drugs
80%
How many drugs are traditional medicine in India, China and Europe
India-7000 China- 5000 and in Europe many Morden drugs originated from traditional medicine
Where does morphine originate form and when was it found
Sap from unrip poppyseed heads as long as Neolithic times
What was used as anaesthetic in 12th century and from where and then in 19th century
Opium from poppies used and by 19th century both opium and morphine used
How do opiate drugs, morphine and opium work as anaesthetic
They reduce nervous action in CNS, if nerves can’t carry impulses then no pain is felt
What is medicinal use of willow bark and for how long
Reduce pain and fever- used for a long time
After discovery of willow bark active ingredients what happened
A way was later found to reduce side effect of stomach bleeding by adding acetyl group which led to development of drugs aspirin and ibuprofen
What animals make use of plants with medicinal properties and how
Monkeys, bears and other animals rub citrus oils on their coats as insecticides and antiseptics to prevent insect bite and infection and birds line their nest eight leaves to protect chicks from blood sucking mites
What do scientists use traditional plant medicines and animal behaviour for
A starting point in search for new drugs
How was aspirin developed
Research into plants used for traditional remedies enabled scientists to isolate active ingredient, this molecule can be analysed and similar molecules can then be manufactured
In recent years where has discovery of natural drugs been focused on
Concentrated on tropical plants
Why has natural drug research been focused on tropical plants
They have great diversity and there are hopes they may contain molecules that could form new medicinal drugs, but it’s important to remember there may be potential uses of wild and cultivated plants in the UK
What is new chemical fingerprinting technology allowing scientists to do
Screen natural chemicals more effectively for their activity as potential medicines
What are pharmaceutical companies research to do with disease causing mechanisms
Ways microorganisms cause disease
How are pharmaceutical companies seeing how microorganisms cause disease
Looking at receptors on plasma membrane like HIV bonds to CD4 and CCR5 receptors on surface of T helper cells, so if binding between pathogen and receptor site can be blocked then disease causing pathogens can’t enter cell
How can pharmaceuticals uses glycoprotein receptor molecules to determine how microorganisms cause disease
Glycoprotein receptor molecules can be isolated and sequenced- once the amino acid sequence is known, molecular modelling can be used to determine shape of receptor
What is the next step in drug research
Finding a drug that mimics the shape of receptor and could be used to bind to virus itself which would block virus entering T helper cells- similarly drugs that inhibit action of certain enzymes can also be developed
How does sequencing technology and molecular modelling have huge potential for future medicines
It’s possible to screen genomes of plants or microorganisms to identify potential medicinal compounds from DNA sequences
What is personalised medicine
When fully developed sequencing technology and molecular modelling may be possible to sequence genes from individuals with certain condition and develop specific drugs for this condition
What is 1 form of synthetic biology
Development of new molecules, especially enzymes that mimic biological systems
What’s another form of synthetic biology
Used to design and construct new devices and systems that may be useful in research, healthcare or manufacturing (eg. Development of tomatoes containing pigment anthocyanin- pigment found in fruits like blueberries and has specific health benefits)
What are anthocyanin
Antioxidants that help protect against coronary heart disease
What are antibiotics
Compounds preventing growth of fungi or bacteria
Is penicillin only antibiotic
No, since Flemings discovery many different compounds with antibiotic properties been discovered
What are most in use antibiotics derivatives of
Compounds made by bacteria form genus streptomyces- antibiotics used widely to treat bacterial infection
What happened before antibiotics
Many died from wound/surgery when they became infected
When did antibiotics come widespread
In ww2 to prevent infection of wounds
What has overuse/ misuse of antibiotics caused
Microorganisms to develop resistance and many currant antibiotics now have limited effectiveness, some bacteria became infamous for their multiple resistance to range of antibiotics
What microorganisms have developed resistance to many antibiotics
Clostridium difficle and methicillin-resistance staphylococcus (MRSA)
