Karteikarten
Immunity
Karten in diesem Stapel (39)
- 1What is the definition of an antigen? Where are they usually found?Molecules (usually proteins) that can generate an immune response when detected by the body. They are usually found on the surface of the cell.
- 2What are antigens used to identify?Pathogens, Cells from other organisms of the same species, abnormal body cells and toxins.
- 3What is a phagocyte? Where are they found?A type of white blood cell that carries out phagocytosis. They're found in the blood and are the first cells to respond to an immune system trigger inside the body
- 4Describe the steps in Phagocytosis1) A Phagocyte recognises the foreign antigens on a pathogen
2) The cytoplasm of the phagocyte moves round the pathogen, engulfing it.
3) The Pathogen is now contained in a phagocytic vesiclen (phagosome) in the cytoplasm of the phagocyte
4) A lysosome (contains digestive enzymes called lysozymes) fuses with the phagocytic vesicle. The lysozomes break down the pathogen by hydrolysis of their cell wall.
5) The soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte
6) The phagocyte then presents the pathogen's antigens- it sticks them on its surface to activate other immune system cells - 5Describe a T Cell and how it is activatedProduced in bone marrow, mature in Thymus Gland.
A type of white blood cell that has receptor proteins on its surface that bind to complementary antigens presented to it by phagocytes, which activate the T Cell. The T Cell then divides by mitosis to produce many different types of clones of the T Cell needed in the immune response. - 6Describe the different types of T CellsT Helper Cells- release cytokines the activate and stimulate phagocytes, cytotoxic T Cells and B Cells.
Cytotoxic T Cells- Kill abnormal and foreign cells as they produce a protein called perforin which makes holes in the cell membrane. The Cell membrane then becomes permeable to all substances and dies.
T Memory Cells- Enable a rapid response to future infections by the same pathogen - 7What type of pathogen are T Cells most effective against and why?Viruses, as viruses replicate inside cells, and the sacrifice of body cells prevents viruses multiplying and infecting more cells.
- 8What are B Cells?Type of white blood cell (made and mature in bone marrow). They're covered with antibodies-proteins that bind antigens to form an antigen-antibody complex. Each B Cell has a different shaped antibody on its membrane so different ones bind to different shaped antigens.
- 9Describe the steps in the B Cell Response1) When the antibody on the surface of a B Cell meets a complementary shaped antigen, it binds to it
2) This, together with substances released from helper T Cells activates the B Cell- this process is called clonal selection.
3) The activated B Cell divides into plasma cells (produce antibodies) or memory cells (responsible for secondary immune response) - 10What is the definition of an antibody?Proteins with specific binding sites synthesised by B Cells
- 11Draw and label the structure of an antibody
- 12Describe the structure of an antibodyMade up of 4 polypeptide chains, 2 light chains, 2 heavy chains. Has a specific bidning site that fits precisely onto a specific antigen (forms antigen-antibody complex). Bindin site is different on each antibody and so is called the variable region. Rest is known as the constant region. It has 2 binding sites meaning it can bind to two pathogens at the same time.
- 13How do antibodies lead to the destruction of pathogens?Pathogens can become clumped together (agglutination), due to the fact antibodies have 2 binding sites. Phagocytes then bind to the antibodies and phagocytose many pathogens at once, leading to the destruction of pathogens carrying this antigen in the body.
- 14Decribe the specificity of antibodiesAntibodies are proteins (made up of chains of amino acids). The specificity of an antibody depends on it s variable regions, which form the antigen binding sites. Each antibody has a variable region with a unique tertiary structure (due to different amino acid sequences) that's complementary to one specific antigen. If the primary structure changes, it would change the shape of the variable regions
- 15Describe the two responses involved in immunityCellular- The T Cells and other immune system cells that they interact with, e.g. phagocytes
Humoral- B Cells, clonal selection and the production of monoclonal antibodies from the humoral response. - 16Describe the primary immune responseWhen an antigen enters the body for the first time it activates the immune system- primary response.
It is slow as there aren't many B Cells that can make the antibody needed to bind to it. Eventually the body will produce enough of the right antibody to overcome the infection- person will feel symptoms. After being exposed to an antigen, both T and B Cells produce memory cells, which remain in the body for a long time. The person is now immune - 17What do memory T Cells and Memory B Cells do?Memory T Cells- Remember the specific antigen
Memory B Cells- Remember the specific antibodies needed to bind the antigen. - 18Describe the secondary immune responseIf the same pathogen enters the body again, the immune system will produce a quicker, stronger immune response. Clonal Selection happens faster. Memory B Cells are activated and divide into plasma cells that produce the right antibody to the antigen. Memory T Cells are activated and divide into the correct type of T Cells to kill the antigen. Don't show any symptoms
- 19Describe how vaccines protect individualsVaccines contain antigens that cause your body to produce memory cells against a particular pathogen, without the pathogen causing disease, meaning you become immune without getting any symptoms. The antigens may be free or attached to a dead or attenuated (weakend) pathogen.
- 20What are the ways you can have a vaccine?Injected or orally
- 21What are the disadvantages of taking the vaccine orally?It could be broken down by enzymes in the gut or the molecules of the vaccine may be too large to be absorbed into the blood.
- 22What are the features of a successful vaccination programme?Lots of the vaccine needed.
Few side effects
Means of producing, storing and transporting must be available.
Trained staff to vaccinate
Possible to vaccinate vast majority of people.
Economically viable - 23What is herd immunity?A sufficiently large proportion of the popuation has been vaccinated to make it difficult for a pathogen to spread within that population. It would be highly improbable for an individual to come in contact with an infected person.
- 24Why might 100% vaccination not be possible?Babies and young children not vaccinated.
Dangerous to vaccinate those who are ill or have compromised immune systems. - 25What is antigenic variation and how does this affect the immune system>Some pathogens change their surface antigens. This antigen variability is called antigenic variation. When you are infected a second time, the memory cells produced from the first infection will not recognise the different antigens, meaning the immune system has to carry out the primary response. It is difficult to develop a vaccine for these diseases as they are constantly changing.
- 26Describe the difficulty with the flu vaccineThe influenza vaccine changes every year as the antigens change regularly, forming new strains of the virus. Memory cells producef from vaccination with one strain of the flu will not recognise other strains with different antigens (immunologically distinct). Each year there are different strains meaning a different vaccine must be made
- 27What is active immunity and the types of it?Type of immunity where you get the your immune system make its own antibodies after being stimulated by an antigen.
Natural- This is when you become immune after catching a disease
Artificial- given a vaccination containing a harmless dose of the antigen - 28What is Passive Immunity and what are the types of it?Given antibodies made by a different organism.
Natural- Baby becomes immune due to antibodies through placenta and breast milk
Artificial: Injected with antibodies from someone else. - 29What are the differences between active and passive immunity?
- 30What are monoclonal antibodies?Antibodies produced from a single group of genetically identical B-Cells (plasma cells), which have been isolated and cloned outside the body. This means that they're all identical in structure. You can make monoclonal antibodies that bind to anything you want.
- 31Describe the use of monoclonal antibodies in treating cancer.Cancer cells have antigens called tumour markers that are not found on normal body cells. Monoclonal antibodies can be made that will bind to the tumor markers. You can attach anti-cancer drugs to the antibodies. When the antibodies come into contact with the cancer cells they will bind to the tumour markers. The means the drug will only accumulate in the body where there are cancer cells. So the side effects of an antibody-based drug are lower than other drugs because they accumulate near specific cells.
- 32Describe how a pregnancy test is carried outThe test detects hCG.
The application area contains antibodies for hCG bound to a coloured bead. When urine is applied to the application area any hCG will bind to the antibody on the beads, forming an antigen-antibody complex. The urine moves up the stick to the test strip, carrying any beads with it. The test strip contains antibodies to hCG that are immobilised. If there is hCG present the test strip turns blue because the immobilised antibody binds to any hCG, concentrating the hCG antibody complex with the blue beads attached. If no hCG is present, the beads will pass through the test area without binding to anything, and so it won't go blue. - 33What is the ELISA Test?This test allows you to see if a patient has any antibodies to a certain antigen or any antigen to a certain antibody. It can be ised to test for pathogenic infections, for allergies and for about anything you can make an antibody for.
- 34Describe how the ELISA Test is carried out.An antibody is used which has an enzyme attached to it. This enzyme can react with a substrate to produce a coloured product, this causes the solution in the reaction to change colour. If there is a colour change it demonstrates that the antigen or antibody of intrest is present in the sample being tested. Sometimes the intensity of the colour can be used to work out the quantity of the antigen/antibody.
- 35What are the different types of ELISADirect ELISA- Single antibody that is complementary to the antigen you're testing for.
Indirect ELISA- Uses two different antibodies. - 36Describe how an indirect ELISA test is carried out. (1st two steps-until end of primary antibody)1) HIV Antigen is bound to the bottom of a well in a well plate.
2) A sample of the patient's blood plasma, which is added to the well. If there are any HIV-specific antibodies these will bind to the HIV antigen stuck to the bottom of the well. The well is washed out to remove any unbound antibodies. - 37Describe how the next two steps of the indirect ELISA test are carried out3) A secondary antibody, that has a specific enzyme attached to it is added to the well. This secondary antibody can bind to the HIV-specific antibdoy. The well is wwashed out again to remove any unbound secondary antibody. If there's no primary antibody in the sample, all of the secondary antibody is washed away.
4) A solution is added to the well. This solution contains a substrate, which is able to react with the enzyme attached to the secondary antibody and produce a coloured product. If the solution changes colour, it indicates that the patient has HIV Specific antibodies in their blood and is infected - 38Why are the washing steps important ?To make sure unbound antibodies aren't left in the well which could affect the results.
- 39What are the ethical issues surrounding vaccines?
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- AS - Level Biology Karteikarten am Immunity, erstellt von Rosie Carver am 28/01/2016.
- Erstellt von
- Rosie Carver
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