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54 Cards in this Set
- Front
- Back
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Two Types of Lymphocytes |
• T lymphocytes - cell mediated immunity (involves body cells), and mature in the thymus gland • B lymphocytes - humoral responses (involves antibodies present in body fluids), and mature in the bone marrow |
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What do protein molecules allow the immune system to identify? (4) |
• Pathogens eg. HIV • Non-self material eg. cells from other organisms of the same species • Toxins eg. those produced by certain pathogens that cause cholera • Abnormal body cells eg. cancer cells |
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What distinguishes one cell from another? |
The variety of specific 3D structure - proteins have vast variety and a highly specific tertiary structure |
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What are the issues for those who have had tissue or organ transplants & how do they attempt to combat these? |
Immune system recognises them as non-self cells and attempts to destroy Donor tissues are matched as closely as possible to the recipient (usually relatives) and immunosuppressant drugs are given |
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What are the issues for those who have had tissue or organ transplants & how do they attempt to combat these? |
Immune system recognises them as non-self cells and attempts to destroy Donor tissues are matched as closely as possible to the recipient (usually relatives) and immunosuppressant drugs are given |
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Clonal Selection |
When an infection occurs and the one type of lymphocyte already present that has the complementary proteins to those of the pathogen is stimulated to divide until it is able to destroy it |
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How Lymphocytes recognise self cells in adults and fetuses? (6) |
• Millions of Lymphocytes that are constantly colliding with other cells in fetus • As infection in fetus is rare due to protection from mother and placenta they almost solely collide with self cells • Some have receptors that exactly fit those self cells & so either die or are suppressed • Only remaining ones are those that may fit non self-cells • In adults - lymphocytes produced in bone marrow only initially only encounter self-antigens • Any that exhibit an immune response undergo apoptosis before they can differentiate into mature ones & no clones of these anti-self lymphocytes will appear in the blood |
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Defence Mechanisms - Non Specific and Specific |
Non Specific - Response is immediate and the same for all pathogens eg. physical barrier (skin), and phagocytosis Specific - Response is slower, and specific to pathogen eg. cell-mediated response (T lymphocytes), and humoral response (B lymphocytes) |
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Difference between Phagocytes and Lymphocytes |
Phagocytes - seek out and kill foreign cells Lymphocytes- are specialised and respond to specific cells & use information from previous encounters to recognise and quickly destroy future ones |
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Phagocytosis Process (6) |
• Chemical products of pathogens or abnormal cells causing phagocytes to move towards them • Phagocytes have receptors on their membrane that recognise and attach to chemicals on the surface of the pathogen • Engulf the pathogen to form a vesicle (phagosome) • Lysosomes move toward the vesicle and fuse with it • Enzymes called lysozymes are in the lysosomes & destroy ingested bacteria by hydrolysis of their cell walls • The solubles products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte |
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Where do phagocytes travel? (2) |
Travel in the blood, but some can move out of the blood vessels into other tissues |
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Antigen |
any part of an organism or substance that is recognised as non-self (foreign) but the immune system and stimulates an immune response |
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How can T Lymphocytes distinguish between invader cells from normal cells in cell-mediated immunity? |
• Phagocytes that have engulfed and hydrolysed a pathogen present some of its antigens • Body cells invaded by a virus present some of the viral antigens • Transplanted cells from individuals of the same species have different antigens on their surface • Cancer cells are different cells from normal cells and present antigens on their membrane |
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Cell-Mediated Immunity/Cellular Response Definition |
T lymphocytes will only respond to antigens that are presented on a body cell (rather than to antigens within the body fluids) |
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Response of T Lymphocytes Process (4) & Cloned T Cells (4) |
• Pathogens invade body cells or are taken in by phagocytes who present antigens on their membrane • Receptors of a specific helper T cell fit exactly onto these antigens • This activates the T cell to divide rapidly by mitosis and form clones • These cloned T Cells: - develop into memory cells that enable a rapid response in future - stimulate phagocytes to engulf pathogens - stimulate B cells to divide and secrete their antibody - activate cytotoxic T cells |
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How do Cytotoxic T Cells Kills Abnormal and Infected Body Cells? & What is it Most Effective against? |
Produce a protein called perforin that makes holes in their cell-surface membrane which makes the membrane freely permeable to all substances and the cell dies Most effective against viruses as they replicate inside cells & so sacrificing body cells prevent viruses multiplying and infecting more cells |
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Are Antibodies Soluble or InSoluble? |
Soluble in the blood and tissue fluid of the body |
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Clonal Selection Definition |
When Helper T Cells bind to the processed antigens and stimulate the B Cells to divide by mitosis to form identical cells all of which produce the antibody that is specific to the foreign antibody |
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Monoclonal Antibody Definition |
When each B Cell clone produces one specific antibody - antibodies that can come from a clone formed by a single B cell |
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Two Types of Cell Produced by B Cell Clone |
• Plasma Cell - Secrete antibodies into blood plasma (survive a few days, and each makes 2000 every sec) & these lead to the destruction of the antigen • Memory Cells - Live longer than plasma cells & circulate in the blood and tissue plasma until they encounter the same antigen where they’ll divide rapidly developing into plasma and memory cells |
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What is the Primary and Secondary Immune Response during Humoral Immunity? |
Primary Immune Response - Production of Antibodies and Memory Cells Secondary Immune Response - Memory Cells are Responsible for it |
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Role of B Cells in Humoral Immunity (4) |
• Surface antigens of an invading pathogen are taken up by a B cell which processes the antigens and presents them • Helper T Cells attach to the antigen on the B cell which activates the B cell which then divides by mitosis to give a clone of plasma cells • Cloned plasma cells produce and secrete the specific antibody that fits the antigen & this antibody attaches to it and destroys it • Some B cells develop into memory cells & these can respond to future infections by the same pathogen by rapid division and developing into plasma cells that produce antibodies |
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Antibody Definition |
Proteins with specific binding sites synthesised by B cells |
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Antibody Definition |
Proteins with specific binding sites synthesised by B cells |
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Antibody Structure (3) |
Made up of four polypeptide chains The chains of one pair are long (called heavy chains) & the chains of the other pair are shorter (called light chains) Connected by disulfide bonds |
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Variable Region of Antibody & Structure (3) |
The Binding Site & Each antibody has two identical ones Binding site consists of a sequence of amino acids that form a specific 3D shape that binds directly to a specific antigen |
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Constant Region of Antibody |
Rest of Antibody & binds to receptors on cells such as, B cells |
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How Antibodies Assist in the Destruction of Bacterial Cells? (3) |
Antibiotics don’t directly destroy antigens but they prepare them for destruction • Cause agglutination of bacterial cells - clumps of bacterial cells are formed, making it easier for phagocytes to locate them as less spread • Serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attached |
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Direct Monoclonal Antibody Therapy with Cancer Cells (3) |
• Monoclonal antibodies are produced that are specific to antigen cancer cells • These antibodies are given to a patient and attach themselves to receptors on their cancer cells • They attach to the surface of their cancer cells and block the chemical signals that stimulate their uncontrolled growth |
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Indirect Monoclonal Antibody Therapy (2) |
Involves attaching a radioactive or cytotoxic drug (drug that kills cells) to the monoclonal antibody & when the antibody attaches to the cancer cell, it kills them Referred to as ‘magic bullets’ and can be used in small amounts to target specific sites |
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How does a Pregnancy Test Work? (3) |
Rely on the fact that the placenta produces the hormone called human chorionic gonadatrophin (hCG) and this is found in mother’s urine Monoclonal antibodies present on test strip are linked to coloured particles & the hCG-antibody-colour complex moves along the strip until it’s trapped by a different type of antibody creating a coloured line |
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Ethical Issues Surrounding Monoclonal Antibodies (3) |
• Involves use of mice - deliberately inducing cancer in them • Have been used successfully to treat many diseases, but their had been many deaths associated with their use in treatment of MS & patient should know all risks and benefits • Testing for safety of new drug presents dangers & in March 2006 six healthy volunteers tested TGN1412 and within minutes suffered multiple organ failure - probably due to T cells overproducing chemicals that stimulate immune response |
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Producing Monoclonal Antibodies (6) |
• Mouse exposed to non-self material so antibody is required & the B cell in the mouse produces a mixture of antibodies which are extracted • To enable these to divide outside the body they are mixed with cells that readily divide outside body (tumour cells) • Detergent added to break down membrane of each cells and enable them to fuse together (hybridoma cells) • Hybridoma cells are separated under microscope and each is cultured to form a clone & tested to see if it producing the right antibody • Correct clones are grown on a large scale and antibodies are extracted • Modified to make them like human cells - humanisation |
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Producing Monoclonal Antibodies (6) |
• Mouse exposed to non-self material so antibody is required & the B cell in the mouse produces a mixture of antibodies which are extracted • To enable these to divide outside the body they are mixed with cells that readily divide outside body (tumour cells) • Detergent added to break down membrane of each cells and enable them to fuse together (hybridoma cells) • Hybridoma cells are separated under microscope and each is cultured to form a clone & tested to see if it producing the right antibody • Correct clones are grown on a large scale and antibodies are extracted • Modified to make them like human cells - humanisation |
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Passive Immunity Definition & Whether or Not it Causes Lasting Immunity? |
When the introduction of antibodies into an individual from an external source leading to immunity but there’s no direct contact with a pathogen There is no lasting immunity as because the antibodies aren’t produced by the individual they’re not replaced when they’re broken down and no memory cells are produced |
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Active Immunity Definition & Whether or Not its Long Lasting? |
Produced by stimulating the production of antibodies by the individual’s own immune system & requires direct contact with the pathogen or its antigen It takes times to develop and is long lasting |
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Two Types of Active Immunity |
• Natural Active Immunity - results from an individual becoming infected with a disease & the body produces its own antibodies and immunity lasts • Artificial Active Immunity - forms the basis of vaccination & involves inducing an immune response in an individual, without them suffering the symptoms of the disease |
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Vaccination & Vaccine Definitions |
Vaccination - introduction of the appropriate disease antigens into the body either by injection of by mouth with the intention to stimulate an immune response against a disease • Vaccine - the material introduced and contains one or more types of antigen from the pathogen and these stimulate the immune response Causes a slight immune response but memory cells are produced |
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Features of a Successful Vaccination Programme (5) |
• Cost - must be economically available in sufficient quantities • Side Effects - must have very few (if any), as may detract others from being vaccinated • Available Means of Producing, Storing, and Transporting Vaccines - technologically advanced equipment, hygienic conditions, and refrigerated transport • Means of Administering - involves training staff with the appropriate skills • Vast Scale - must be possible to vaccinate the vast majority of the vulnerable population to produce herd immunity |
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Herd Immunity (2) |
Arises when a large proportion of the population has been vaccinated to make it difficult for a pathogen to spread Based on the idea that pathogens are spread from close contact & it’s important as it’s never possible to vaccinate everyone |
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Why Vaccination may not Eliminate a Disease? (6) |
• Fails to induce immunity in certain individual such as, those with defective immune systems • Individuals may develop the disease immediately after vaccination before immunity levels are high enough & they may harbour it and reinfect others • Pathogen may mutate frequently with its antigens changing suddenly & this means the vaccine suddenly become ineffective & this antigenic variability happens with the flu • Many varieties of a particular pathogen so almost impossible to develop an effective vaccine against them all • Some pathogens ‘hide’ from the body’s immune system by concealing themselves inside cells or living in out of reach places eg. intestines • Individuals may have religious, ethical, or medical reasons for objections against vaccinations |
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Human Immunodeficiency Virus Structure (6) |
• Attachment Proteins • Lipid Envelope • Matrix • Capsid • Genetic Material (RNA) • Reverse Transcriptase (Enzyme) |
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What Group of Viruses is HIV in? |
Retroviruses - due to reverse transcriptase that catalyses the production if DNA to RNA |
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Replication of HIV (7) |
• HIV enters bloodstream and circulates body • Protein of HIV bunds to protein CD4 (most readily attaches to helper T cells) • Protein capsid fuses with the cell-surface membrane and RNA and enzymes of HIV enter the helper T cells • HIV reverse transcriptase converts the virus’ RNA into DNA which is moved into helper T cell’s nucleus and into its DNA •HIV DNA in the nucleus creates messenger RNA using the cell’s enzyme & this mRNA contains the instructions for making new viral proteins and the RNA to go into the new HIV • The mRNA passes out of the nucleus through a nucleus pore and uses the cell’s protein synthesis mechanisms to make HIV particles • HIV particles break away from helper T cells with a piece of its membrane surrounding them which forms their lipid envelope |
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How does HIV cause the Symptoms of AIDs |
• HIV attaches helper T cells & HIV causes AIDs by interfering with their normal function People normally have between 800 and 1200 helper T cells & infected people could have as low as 200 Helper T cells are essential in cell-mediated immunity |
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What is the ELISA Test? |
Stands for Enzyme Linked Immunosorbant Assay & it uses antibodies to detect the presence and quantity of a protein in a sample |
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ELISA Test Process |
• Apply the sample to a surface to which all the antigens will attach & wash the surface repeatedly to remove any unattached antigens • Add the antibody that is specific to the antigen that is trying to be detected & leave them to bind • Wash the surface to remove excess antibody • Add a second antibody that binds with the first & this second antibody has an enzyme attached • Add the colourless substrate of the enzyme & the enzyme acts on the substrate, making it coloured • Amount if antigen present is relative to the intensity of colour that develops |
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What is the ELISA test useful for? |
Used to detect HIV and pathogens of diseases such as, TB and hepatitis Is useful where the quantity of an antigen needs to be measured such as, testing for particular drugs in the body (as many drugs are naturally in low concentrations) |
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Why are Antibiotics ineffective against viral diseases like AIDs but effective to bacteria (3) |
• Antibiotics often work by preventing bacteria from making normal cells walls • Water constantly enters bacterial cells by osmosis & the cell doesn’t burst due to its cell wall made of murein which is tough, hard to stretch, and is inelastic • Antibiotics inhibit certain enzymes required for the synthesis and assembly of the peptide cross-linkages in bacterial cell walls & this weakens the wall so the bacteria cells bursts and the cell dies |
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Why are Antibiotics ineffective against viral diseases like AIDs but effective to bacteria (3) |
• Antibiotics often work by preventing bacteria from making normal cells walls • Water constantly enters bacterial cells by osmosis & the cell doesn’t burst due to its cell wall made of murein which is tough, hard to stretch, and is inelastic • Antibiotics inhibit certain enzymes required for the synthesis and assembly of the peptide cross-linkages in bacterial cell walls & this weakens the wall so the bacteria cells bursts and the cell dies |
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Why are antibiotics ineffective against AIDS? (4) |
• Viruses rely on the host cells to carry out their metabolic activities and so lack their own metabolic pathways and structures • Antibiotics are ineffective as there are no metabolic mechanisms or cell structures for them to disrupt • Viruses have a protein coat rather than murein cell wall & don’t have a site where antibiotics can work • When viruses are within an organism’s cells, antibiotics can’t reach them |
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Why are Antibiotics effective against bacteria? (3) |
• Antibiotics often work by preventing bacteria from making normal cells walls • Water constantly enters bacterial cells by osmosis & the cell doesn’t burst due to its cell wall made of murein which is tough, hard to stretch, and is inelastic • Antibiotics inhibit certain enzymes required for the synthesis and assembly of the peptide cross-linkages in bacterial cell walls & this weakens the wall so the bacteria cells bursts and the cell dies |
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Why are antibiotics ineffective against AIDS? (4) |
• Viruses rely on the host cells to carry out their metabolic activities and so lack their own metabolic pathways and structures • Antibiotics are ineffective as there are no metabolic mechanisms or cell structures for them to disrupt • Viruses have a protein coat rather than murein cell wall & don’t have a site where antibiotics can work • When viruses are within an organism’s cells, antibiotics can’t reach them |
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How does HIV replicate? |
Uses its genetic material to instruct the host cell’s biochemical mechanisms to produce the components required to make new HIV |
