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44 Cards in this Set
- Front
- Back
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Define Pathogen
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A microorganism that causes a disease
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Define immunity
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The means by which the body defends itself from infection
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How do lymphocytes(1) in a foetus, recognise cells belonging to the body?
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in foetus, (1) are constantly colliding with other cells. infection is rare so the cells will be that of the body. Some of the (1) will have receptors that exactly fit those of the body and die or are suppressed. remaining (1) are those that fit (and respond) to foreign material.
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How do lymphocytes(1) produced by adult bone marrow, recognise cells belonging to the body?
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(1) in the bone marrow only encounter self-antigens Any (1) that respond/ show an immune response to these antigens undergo apoptosis before they can differentiate into mature (1). No clones of these will appear in the body leaving only those (1) that will respond to non-self antigens. |
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Define Phagocytosis
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mechanism by which cells engulf particles to form vesicles or a vacuole
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Describe what happens during Phagocytosis Pathogen (1) Phagocyte (2) Lysozymes (3) |
(1) releases chemicals which attract (2) (along a concentration gradient) (1) attach to (2) cell surface receptors and is engulfed by the (2) (3) attach to phagosome and release lysozymes which hydrolyse the bacterium hydrolysis products are ejected (exocytosis). An antigen presenting cell appears on cell surface |
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Define Antigen
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a protein molecule that triggers an immune response by lymphosytes
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What are B lymphocytes?
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a type of white blood cell that is produced and matures within the bone marrow. They produce antibodies as part of their role in immunity
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What are T Lymphocytes?
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a type of white blood cell that is produced within the bone marrow and matures in thymusglands. They coordinate the immune response and kill infected cells
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How can T-lymphocytes distinguish invader cells from normal cells?
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1. some phagocytes have antigen presenting cells on the cell surface of the phagocytes 2. body cells invaded by a virus present some of the viral antigens on their cell surface 3. Transplanted cells have different antigens on their cell surface 4. Cancer cells are different from normal cells and present their antigens on their surface |
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What are the stages of T-lymphocyte response to infection?
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1. Phagocytosis occurs and antigen presenting cells appear 2. receptors of specific TH cells fit exactly to these antigens 3. Attachment causes T helper cells to divide rapidly by Mitosis and clone |
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What can the cloned T helper cells differentiate to?
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Memory T cells Stimulate phagocytosis stimulate B cells to divide Activate Cytotoxic T cells |
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How do Cytotoxic T cells kill infected cells?
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Produce perforin (Protein) that makes holes in cell surface membrane. These holes allow cell membrane to permeable to all substances and cell dies as a result.
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What immunity is T cells?
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Cell-mediated immunity
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What immunity is B cells?
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Humoral immunity (involves antibodies) |
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What is a property of antibodies that make it good for secondary immunity?
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soluble in the blood and tissue fluid of the body
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Define antibody
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a protien produced by the lymphocytes in response to the presence of a complementary antigen
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What are the stages of the response of B cells (1)? Antibody(2) T helper cell (3) Antigen (4) |
(2) attaches to complementary (4). (4) enters (1) by endocytosis and presents on surface (3) binds to (4) and stimulates (1) to divide by mitosis and clone (Clonal selection) Each clone can differentiate into plasma cells or B memory cells. |
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What do the plasma cells do?
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Secrete antibodies into the blood plasma which survive for a few days. Responsible for immediate response against infection and are known as the primary immune response.
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What do memory cells do?
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1. Secodary immune response 2. live longer than plasma cells 3. circulate in blood and tissue fluid 4. when interacting with the same antigen again they divide rapidly and make more plasma cells and memory cells. Higher quantities of are antigens released and at a faster rate than primary response |
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What is the structure of an antibody?
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A- Variable region C- Constant region Bottom is the receptor binding site Has disulphide bonds 4 polypeptide chains |
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How do antibodies lead to the destruction of the antigen?
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Cause agglutination of the bacterial cells (clumps bacterial cells together) making it easier for Phagocytes to locate then Serve as markers that stimulate phagocytes to engulf the bacterial cells to which they attach |
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What are monoclonal antibodies?
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isolation and cloning of an antibody to form identical antibodies.
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How do monoclonal antibodies target cancer cells?
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1. produced so that they are complementary to the antigens of the cancer cell 2. These antibodies are given to patients and attach themselves to the receptors on their cancer cells 3. They attach to to the surface of the cancer cell and block the chemical signal that Stimulates their uncontrolled growth |
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How are monoclonal antibodies used in pregnancy testing?
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1. Placenta produces a hormone (hCG) which is present in the mothers urine. 2. Monoclonal antibodies are present on test strip are linked to coloured particles 3. If hGC is present then it binds to the antibodies forming a hGC-antibody-colour complex which moves along strip intil it is trapped by a different type of antigen, creating a coloured line. |
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What are the ethical issues of Monoclonal antibodies?
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Production involves the use of mice There have been deaths associated with the use in multiple sclerosis. There must be informed consent Testing for safety is dangerous. e.g. 2006 6 healthy volunteers took part in a trail. within minutes they suffered multiple organ failures |
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What are some advantages of Monoclonal antibodies?
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Antibodies are not toxic and highly specific so there are less side effects than other forms of therapy. have been used successfully to treat a number of diseases including cancer and diabetes, saving many lives |
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What is passive immunity?
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Produced by the introduction of antibodies into individuals from an outside source. No direct contact with the pathogen or its antigen is necessary to induce immunity. immunity acquired immediately. Antibodies not replaced and no memory cells formed. no lasting immunity e.g. snake bite |
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What is active immunity?
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Produced by stimulating the production of antibodies by the individuals' own immune system. direct contact with the pathogen or its antigen is needed. Immunity takes long to develop. generally long lasting |
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What are the two types of active immunity?
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Natural active immunity Artificial active immunity |
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What is Natural active immunity?
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Results from individuals becoming infected with a disease under normal circumstances. the body produces its own antibodies and may continue to do that for many years.
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What is Artificial active immunity?
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Forms the basis of vaccination ( Immunisation) . it involves inducing an immune response in an individual, without them suffering the symptoms of the disease.
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define vaccination
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the introduction of a vaccine containing appropriate disease antigens into the body, by injection or mouth in order to induce artificial immunity
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What does the success of a vaccine depend on?
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1.Economically available in sufficient quantities to immunise the most vulnerable population 2.Few Side effects so no discouragement 3.Means of (Hygienic) production, storage and transport of vacine must be available 3. Must be posible to vaccinate vast majority 4. There must be means of administering it at appropriate times. e.g training staff |
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What is Herd Immunity?
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sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within a population.
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Why might vaccines not eliminate the disease?
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1.Diffective immune systems& religious reasons 2.Individuals may develop disease immediately after vaccine and may infect others 3.pathogens may mutate frequently (High antigen variability) 4. may be many varieties of the pathogen that its immpossible to develop a vaccine againstg them all |
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What are ethical issues of using vaccines?
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often uses animals have side effects that m at cause long term harm and unkown health risks on new vaccines should it be compulsory? expensive vaccination means less people can afford cheap vaccination means less money for research and developement |
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What Does HIV stand for?
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Human Immunodeficiency Virus
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What does AIDS stand for?
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Aquired immune deficiency syndrome
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What is the structure of HIV?
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includes Matrix (Retro Virus) |
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how does the replication of HIV work? Protien (A) HIV (B) T helper cells(C) Nucleus (D) Reverse transcriptase (E) mRNA(F) |
(1)(B) circulates around body. (2) (A) on (B) readily binds to a (A) called CD4, normally found on (C) and infuses with the cell surface membrane. RNA and (E) enter cell. (4) (B) (E) catalysis RNA to DNA and inserts into (C) (D). creates (F) which contains instructions for making new viral (A) . (F) passes out of nucleus through a (D)pore and make (B)particles. (B)particles burst from cell, killing it. |
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What happens in the ELISA test?
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sample applied to surface-antigens present. washed to remove unattached antigens. add antibodies that are specific to the antigen which bind. surface washed again. second antibody is complementary to first wave have an enzyme attached. colourless substrate added and complementary enzyme causes a colour to be present |
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Why are antibiotics ineffective against viral diseases like AIDS?
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Virus rely on host cells to carry out their metabolic reactions so lack their own metabolic pathways and cell structures so antibiotics cannot disrupt their metabolic pathways and have no sites where antibiotics can work on.
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How do antibiotics work against bacteria?
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Water constantly enter by osmosis but bursting is prevented by murine in cell walls allowing it to remain turgid. However, antibodies weaken the cell wall and so bacteria bursts.
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