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54 Cards in this Set
- Front
- Back
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Define - antigens |
A molecule (usually a protein) that can generate an immune response |
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Antigens allow the immune system to identify: |
• pathogens (organisms that cause disease - viruses, bacteria, fungi)Describ • abnormal body cells (cancerous or pathogen-infected, have abnormal antigens) • toxins • cells from other individuals of the same species (organ transplant/ blood transfusion will be rejected unless immune system suppressed) |
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Describe the structure of an antibody? Explain how this relates to its function? |
• They’re proteins • same constant regions • different variable regions (forms the antigen binding sites). The variable regions of each antibody has a unique tertiary structure, due to different amino acid sequences, allowing it to bind to one specific antigen only |
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Draw an antibody |
Back (Definition) |
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The immune response is split into two. |
• Cellular • Humoral |
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What is meant by the ‘cellular’ immune response? |
The T-cells and other cells they interact with (e.g. phagocytes) |
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What is meant by the ‘Humoral’ immune response? |
The B-cells, clonal selection, production of monoclonal antibodies |
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What is meant by The primary immune response? |
When an antigen enters the body for the first time and activates the immune system |
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Why is the primary response slow? |
There aren’t many B cells that can make the antibodies needed to bind to the pathogen. • phagocytosis is slow - can’t phagocytose many pathogens at once |
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Primary response -> Eventually enough antibody produced, body overcomes the infection (but this takes time) Meanwhile... Person will show symptoms of the disease |
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What happens after a primary immune response that causes a person to be immune to a pathogen? |
T-cells and B-cells produce memory cells. • These memory cells remain in the body for a long time • Memory cells remember the specific antigen, and record the antibodies needed to bing to it |
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What is meant by the secondary immune response? |
When the same pathogen enters the body for the second time (Where a primary immune response was already generated against it) |
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What are the properties of the secondary immune response in comparison to the primary immune response? |
• quicker • stronger |
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Why is the secondary response faster than the primary response? |
• Memory B-cells activated, divide into plasma cells (that produce the correct antibody). Clonal selection faster. • Memory T-cells activated, Divide into the correct type of Tc cells to kill the cell carrying the antigen |
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Secondary response -> Infected person will show no symptoms (get rid of pathogen quickly) |
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Click to see what a graph of the primary immune response and then secondary immune response might look like. |
Back (Definition) |
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Immunity can be active or passive. Define - active immunity? |
Immunity you get when your immune system makes its own antibodies after being stimulated by an antigen Two types: • natural - immune after catching a disease • artificial - immune after being given a vaccination |
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After a primary response, the person is now immune to the pathogen. |
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Immunity can be active or passive. Define - passive immunity? |
Immunity you get from being given antibodies made by a different organism - your immune system doesn’t produce any antibodies Two types: • natural - baby becomes immune due to antibodies it receives from mother (through placenta/in milk) • artificial - injected with antibodies from someone else |
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Differences between active immunity and passive immunity? |
Active: • Requires exposure to antigen • Longer time for protection to develop (primary response needed) • Memory cells are produced • Protection is long-term (memory cells remain, antibody can be produced on activation) Passive • protein is immediate • protection is short-term - antibodies are broken down |
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Differences between active immunity and passive immunity? |
Active: • Requires exposure to antigen • Longer time for protection to develop (primary response needed) • Memory cells are produced • Protection is long-term (memory cells remain, antibody can be produced on activation) Passive • protein is immediate • protection is short-term - antibodies are broken down |
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Define - vaccine? |
Injected with a dead or attenuated (weakened) form of a pathogen • Antigens are present -> body produces memory cells • so you get immunity (if pathogen gets in the body again it is removed before disease occurs) • but the pathogen doesn’t cause disease -> so you show no symptoms |
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Define - vaccine? |
Injected with antigens: either free antigens, or attached to a dead or attenuated (weakened) pathogen • Antigens are present -> body produces memory cells • so you get immunity (if pathogen gets in the body again it is removed before disease occurs) • but the pathogen doesn’t cause disease -> so you show no symptoms |
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What is herd immunity and how do vaccinations give it? |
In a population, those not vaccinated against a disease are less likely to catch it, if most of the population is vaccinated (Fewer people to catch it from) |
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Why are booster vaccines sometimes taken several years after the first vaccine? |
To make sure that more memory cells are produced |
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Are the disadvantages of taking a vaccine orally? |
• Could be broken down by enzymes in the gut • Molecules of the vaccine may be too large to be absorbed into the blood |
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What are the ethical issues around the use of vaccines? |
• tested on animals • testing on humans risky - people may put themselves at unnecessary risk - unprotected sex after given new HIV vaccine • some people don’t take vaccine as fear side effects, still protected by herd immunity - unfair? • Epidermic of a new disease - difficult decisions - who get’s the vaccine first? |
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What are the ethical issues around the use of vaccines? |
• tested on animals • testing on humans risky - people may put themselves at unnecessary risk - unprotected sex after given new HIV vaccine • some people don’t take vaccine as fear side effects, still protected by herd immunity - unfair? • Epidermic of a new disease - difficult decisions - who get’s the vaccine first? |
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What is antigenic variation? |
Some pathogens can change their surface antigens (due to changes in the genes of a pathogen forming new antigens) |
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What is antigenic variation bad? |
1. When you’re infected a second time: • memory cells don’t recognise the different antigens • immune system has to generate a primary immune response again • You get ill again - show symptoms 2. Also makes it difficult to develop vaccines against pathogens e.g. flu (influenza) |
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What is antigenic variation bad? |
1. When you’re infected a second time: • memory cells don’t recognise the different antigens • immune system has to generate a primary immune response again • You get ill again - show symptoms 2. Also makes it difficult to develop vaccines against pathogens e.g. flu (influenza) |
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What is meant by strains? |
Pathogens of the same type that show antigenic variation (Have different antigens) |
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What is meant by strains? |
Pathogens of the same type that show antigenic variation (Have different antigens) e.g. there are different strains of influenza virus |
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What are the ways we can use monoclonal antibodies in medicine? |
• targeting medication to specific cells - therapeutic drug is attached to an antibody that binds to a certain type of cell e.g. cancer cells. This reduces any side effects as normal cells are not damaged. • medical diagnosis - pregnancy tests |
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What is the purpose of an ELISA test? |
Allows you to see if a patient has any antibodies in their body that are complementary to a certain antigen. (Or antigens in their body to a certain antibody) Makes it useful in: • testing for pathogenic infection • test for allergies |
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Describe how a Direct ELISA test is done? |
• Antigens from the patient sample are bound to the inside of a well in a well plate • a detection antibody (with an attached enzyme) complementary to the antigen of interest is added • if antigen of interest present -> the detection antibody will bind to it • well washed out -> removes unbound antibodies • substrate solution added • if detection antibody is present -> the enzyme reacts with the substrate to give a colour change |
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How is an indirect ELISA done? |
• same as direct but uses 2 different antibodies • first antibody binds to antigen, second antibody (with enzyme attached) binds to the first antibody, substrate reacts with enzyme |
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What are the ethical issues surrounding the use of monoclonal antibodies? |
Animals used to produce the cells from which the monoclonal antibodies are produced |
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What is HIV? |
A virus that affects the human immune system. Eventually leads to AIDS (acquired immune deficiency syndrome) |
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How does HIV cause harm? |
• infects TH cells - act as the host cells • HIV replicates rapidly inside host cells • eventually kills TH cells • TH activate phagocytes, TC cells, B-cells - so without enough helper T-cells - an effective immune response can’t happen |
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At what point do HIV patients have AIDS? |
When the helper T-cell numbers become critically low |
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Patient infected with HIV • At first -> HIV replicates rapidly, patient experiences flu-like symptoms • Then HIV replication rate drops -> the Latency period. Patients experience no symptoms. |
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The length of time between infection with HIV and the development of AIDS varies between individuals |
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Symptoms of AIDS? |
• initial symptoms - minor infections mucus membranes (e.g. nose, ears, genitals), chest infections • As AIDS progresses -> patient susceptible to more serious infections (e.g. tuberculosis) as immune system cells decrease • Late stages -> serious infections, parasite infections of the brain -> these are the things that kill patients (not HIV itself) |
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Draw and label a HIV particle? Give some of the functions of the organelles? |
Back (Definition) |
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Describe how HIV replicates? |
• The attachment protein attaches to a receptor molecule on the cell membrane of the host helper T-cell • The capsid is released into the cell where it uncoats and releases the RNA (genetic material) into the cell’s cytoplasm • Inside the cell reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template • From this, double-stranded DNA is made + inserted into the human DNA •Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA • The viral proteins are assembled into the new viruses, which bud from the cell and go on to infect other cells
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Describe how HIV replicates? |
• The attachment protein attaches to a receptor molecule on the cell membrane of the host helper T-cell • The capsid is released into the cell where it uncoats and releases the RNA (genetic material) into the cell’s cytoplasm • Inside the cell reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template • From this, double-stranded DNA is made + inserted into the human DNA •Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA • The viral proteins are assembled into the new viruses, which bud from the cell and go on to infect other cells • cell ruptures and dies |
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Describe how HIV replicates? |
• The attachment protein attaches to a receptor molecule on the cell membrane of the host helper T-cell • The capsid is released into the cell where it uncoats and releases the RNA (genetic material) into the cell’s cytoplasm • Inside the cell reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template • From this, double-stranded DNA is made + inserted into the human DNA •Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA • The viral proteins are assembled into the new viruses, which bud from the cell and go on to infect other cells • Host cell ruptures and dies |
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Why are Antibiotics ineffective against viruses? |
• Antibiotics kill bacteria by interfering with the metabolic reactions - they target the bacterial enzymes and ribosomes • antibiotics designed so that they don’t damage human enzymes and ribosomes • Viruses don’t have their own enzymes and ribosomes they use the ones in the host cell to replicate • Antibiotics therefore can’t inhibit them because they’re designed to not target human processes
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Why are Antibiotics ineffective against viruses? |
• Antibiotics kill bacteria by interfering with the metabolic reactions - they target the bacterial enzymes and ribosomes • antibiotics designed so that they don’t damage human enzymes and ribosomes • Viruses don’t have their own enzymes and ribosomes they use the ones in the host cell to replicate • Antibiotics therefore can’t inhibit them because they’re designed to not target human processes |
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How do most antiviral drugs work? |
Target the few virus-specific enzymes that exist |
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How do most antiviral drugs work? |
Target the few virus-specific enzymes that exist e.g. reverse transcriptase |
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Currently no cure or vaccine for HIV. But antiviral drugs can be used to slow down the progression of HIV infection to AIDS. |
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Currently no cure or vaccine for HIV. But antiviral drugs can be used to slow down the progression of HIV infection to AIDS. What is the best way to control HIV infection in a population currently? |
Reduce it’s spread. • no unprotected sex • no sharing of needles - infected bodily fluids • HIV positive mother to her fetus - not all babies will have HIV though and antiviral drugs can reduce the chance further |
