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91 Cards in this Set
- Front
- Back
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What is a pathogen? |
Microorganism that stimulates immune response |
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What is an antigen? |
Protein found on cell surface membrane that stimulates immune response |
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What is the first line of defence against disease? |
Physical barriers e.g. skin, ciliated epithelial and goblet cells, HCL acid in stomach Non-specific |
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What is the second line of defence against disease? |
Phagocytosis Non-specific |
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What is the third line of defence against disease? |
Cell mediated immunity - T-lymphocytes Humoral immunity - B-lymphocytes Specific |
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What is a specific response? |
Slower and specific to each pathogen |
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What is a non-specific response? |
Immediate and same for all pathogens |
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What does the skin do? |
Covers body surface and forms tough outer layer/ barrier to entry of pathogens |
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What do the ciliated epithelia covered in mucus do? |
Pathogens stick to mucus Transported away by cilia to trachea Swallowed and enters stomach |
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What does hydrochloric acid do? |
Low pH destroys pathogens in the stomach |
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What do tears do? |
Contain lysosomes to break down pathogens |
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What are the four different types of white blood cells? |
Phagocytes for phagocytosis Granulocytes for inflamation T Lymphocytes for cell-mediated immunity B Lymphocytes for antibody-mediated immunity |
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What is the first stage of phagocytosis? (1/5) |
Pathogen produces chemoattractions, causing phagocytes to move towards it |
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What is the second stage of phagocytosis? (2/5) |
Phagocyte binds to pathogen |
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What is the third stage of phagocytosis? (3/5) |
Phagocyte engulfs pathogen, forming vesicle - phagosome |
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What is the fourth stage of phagocytosis? (4/5) |
Lysosomes moves towards phagosome and fuses with it |
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What is the fifth stage of phagocytosis? (5/5) |
Hydrolytic enzymes in lysosome hydrolyse pathogen to soluble products + absorbed to phagocyte cytoplasm |
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How do lymphocytes recognise their own cells? |
Lymphocyte receptors collide w/ self cells in fetus + fit antigens on them Lymphocytes die / fit foreign materials - non-self /suppressed |
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What do T-cells do? |
Respond to organism's own cells when infected w/ non-self material |
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How are T-cells formed? |
In bone marrow Mature in thymus gland |
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What is the first stage of antigen presentation? |
Macrophage that engulfed pathogen presents own antigens on cell surface membrane |
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What occurs after antigen presentation? |
Specific T-cells w/ specific receptor/binding site bind w/ antigen |
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What do cytoxic (killer) T-cells do? |
Release perforin proteins that make holes in cell membrane of infected cells to kill them |
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What do helper T-cells do? |
Bind to antigens Secrete cytokines Stimulate phagocytes Stimulate specific B-cell division |
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What do memory T-cells do? |
Remain in blood/ lymphs for decades so antigen identified more quickly and rapidly divide into killer + helper T cells |
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What is a B cell? |
Complementary antibody to antigen stimulated by helper T-cells to divide by mitosis forming memory/ plasma cells |
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What is a memory B cell? |
Remain in blood - if same pathogen w/ same antigen invades again - produce more antibodies faster |
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What is a plasma B cell? |
Produce lots of antibodies - will have specific complementary shaped binding sites to pathogen |
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What is the order of the formation of memory and plasma B cells? |
T-cell divides by mitosis = helper T cells = stimulate division of specific B cells = memory B + plasma B cells |
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What does the receptor and antigen fitting together do? |
Activate T-cell to divide rapidly by mitosis to form clone of Killer, Memory and Helper T-cells |
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What is humour? |
Body fluids e.g. blood/ tissue fluid |
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What are antibodies? |
Hinged soluble protein with specific binding sites so attach to complementary antigen |
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What is agglutination? |
Antibodies form clumps of pathogens so easier for phagocytes to locate and digest |
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How do antibodies prepare antigens for destruction? |
Agglutination Soluble toxin insoluble so engulfed in phagocytosis |
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What is antigenic variability? |
Secondary immune response doesn't work as antigens of pathogens change via DNA mutation |
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Why does DNA mutation mean that secondary immune response doesn't work? |
Antibodies from primary response not complementary shape so won't bind to new antigen - causes new primary response - slower + symptoms |
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What is active immunity? |
Stimulated antibody production by own immune system - long-lasting |
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What is active natural immunity? |
Primary immune response after infection |
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What is active artificial immunity? |
Vaccination containing modified virulent antigens administered to stimulate primary response |
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What does virulent mean? |
Non-pathogenic + dead/ inttenuated |
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What is passive immunity? |
Introduction of antibodies from outside source - short-lived - antibodies recognised as antigens + broken down by immune system |
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What is passive natural immunity? |
Antibodies via placenta, colostrum and breast milk |
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What is passive artificial immunity? |
Injection with antiserum - antibodies to destroy harmful antigens |
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What is a monoclonal antibody? |
Produced from a clone of hybrid B-lymphocytes/myeloma cells |
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How are monoclonal antibodies produced? |
Mouse spleen cell rich in lymphocytes fused with certain myeloma (cancer) cells, which can divide rapidly |
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What is a magic bullet? |
Antibodies have specific shaped binding sites that will only bind to a specific antigen (protein) |
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What is the use of a magic bullet? |
Target specific cells or substances |
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What is herceptin? |
Monoclonal antibody used to treat breast cancer - non-toxic - highly specific - fewer side effects |
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How does herceptin function? |
Antibodies attach to receptors on cancer cells and block chemical signals that stimulate uncontrolled growth |
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How do magic bullets function? |
Inactive/cytoxic drug attached to antibody which attaches to cell so drug kills cell only 2nd drug administered to activate inactive drug |
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What are the benefits of magic bullets? |
Can be used in smaller doses as they target specific sites Cheaper Reduces side effects |
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What is the ELISA test and what does it do? |
Enzyme linked immunosorbant essay - detects presence/ concentration of protein in sample - detects HIV, TB, Hepatitis + prostate specific antigen |
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What is HCG? |
Human Chorionic Gonadotropin Found in urine Produced by placenta |
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How is a positive ELISA test carried out? 1/2 |
Blood sample w/ specific fixed antigen e.g. anti-PSA antibodies - WASH PLATE TO REMOVE NON-COMPLEMENTARY SHAPED ANTIBODIES FROM WELL |
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How is a positive ELISA test carried out? 2/2 |
+ enzyme + antibody - WASH PLATE TO REMOVE UNBOUND ENZYME LINKED ANTIBODIES TO AVOID FALSE POSITIVE detector solution = colour change |
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How is a negative ELISA test carried out? |
Positive but blood sample w/ no antigen so nothing binds = no colour change |
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What is the reaction zone? |
Anti-HCG antibodies become mobilised Urine reaches first |
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What is the test zone? |
Immobilised enzyme linked anti-HCG antibodies unless negative then doesn't bind |
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What is the control zone? |
Enzyme linked anti-mouse antibodies - binds to show test is correct |
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How does a pregnancy test function? |
Urine drawn up by capillary action + binds to HCG antibodies which bind to 2nd set = colour change + unbound move to control + form enzyme-substrate complex |
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What are essential in successful vaccination programmes? |
'herd immunity' Economically viable Few side effects Sufficient quantities Suitable production/storing/transport |
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What is herd immunity? |
Vaccination provided to all population at risk to stop infection spreading |
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Why don't vaccines eliminate diseases? |
Defective immune systems Immediate disease Antigenic variability Too many pathogen varieties Moral/religious/ethical objections |
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What is cholera and why is it hard to treat? |
Intestinal disease which makes antigens change rapidly - spread by mobile populations |
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What makes a person more likely to contract TB? |
HIV - impaired immune system Poor living conditions, ageing/mobile population |
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What is the link between MMR and autism? |
1988 - 3 vaccines 1998 - medical journalist suggests autism link Media attention + false evidence - MMR incidents rose |
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What is cervical cancer? |
HPV - spread by sexual contact - vaccine to protect ( 2 strains ) |
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What are the problems with scientific research? |
Needs critical praise by others Personal bias Media bias New knowledge challenges |
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What are ethical issues around research? |
Side effects Animal testing Health risks Compulsory vaccinations? |
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What are the qualities of a virus? |
Not a cell-like structure 50× smaller than bacteria Only reproduce in host cells Contains genetic material - DNA/RNA |
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What is the structure of viruses? |
Protective protein coat - CAPSID Made from sub-units - capsomeres Lipid membrane around capsid |
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What is HIV? |
Human Immunodeficiency virus |
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What is the shape of HIV? |
Spherical shape Cone-shaped capsid |
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What are the qualities of a retro virus? |
Contains RNA Enzyme-reverse transcriptase allows links to make DNA copy of RNA when it infects host cell |
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What does the DNA copy in the retro-virus do? |
Inserts itself into host cells chromosomes May remain inactive for years |
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What happens when viral DNA become active? |
It instructs the cell to make viral proteins |
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What is the structure of a virus? |
Lipid membrane with lipids and gylcoprotiens Protein knobs on surface (acts as antigen) |
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How does HIV cause disease? (1/3) |
Enters blood, infects T-helper cells, binds to cell surface protein on T-helper, capsid fuses w/ host cell membrane, RNA + enzymes enter T-cell |
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How does HIV cause disease? (2/3) |
Reverse transcriptase enzymes used to make DNA copy of RNA |
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How does HIV cause disease? (3/3) |
DNA copy inserted into chromosome of helper T-cell - remains normal, no symptoms - divides by mitosis |
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How are HIV particles made? |
DNA creates mRNA Viral mRNA passes out of nuclear pore + attracts to ribosome to make HIV particles |
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What do viral particles do? |
'bud-off' from host cell using host cells membrane to form lipid envelope and enter more helper T-cells |
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What causes full AIDS? |
Helper destroyed - can't activate B-cell - immune system impaired |
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How is the immune system impaired? |
HIV attacks T-helper cells Cytoxic T-cells can't be made B-cell not stimulated - no antibodies No sufficient immune response |
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What does a weakened immune system do? |
Make a person susceptible to opportunistic diseases E.g. kaposi's sarcoma, tb, cancer, pneumonia |
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How is HIV spread? |
Body fluids mix - direct contact Unprotected sex Needle sharing Across placenta Blood transfusion |
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How are viruses treated? |
Virus don't show activity till in host - antiviral drugs |
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How do viruses replicate? |
Virus attach to host w/ attachment proteins, nucleic acids inject into cell, gives genetic code for host to make viral proteins, assembled - make new virus + released |
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What are the stages of binary fission? |
DNA replicated - Cytoplasmic membrane elongates - separates DNA molecules, cross wall forms, membrane invaginated, cross wall forms completely = daughter cells |
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Explain the advantage of using rate of uptake in an investigation with different starting numbers. |
To allow comparison |
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Percentage increase = |
(Difference / Original) × 100 |
