Flashcards
module 2C
Flashcards do conjunto (39)
- 1what are antigens, where are they found and what job do they do-molecules that can generate an immune respnse when detected by the body
-surface of cells
-identify pathogens, abnormal body cells and toxins - 21. how do phagocytes engulf pathogens1. phagocyte RECOGNISES foreigh antigens pathogen
2. CYTOPLASM engulf pathogen
3. pathogen contained in phagocytic vacuole
4. lysosome fuses with vacule. lysozymes break down pathogen
5. phagocyte presents antigens (to activate other immune system cells) - 32. how do phagocytes activate T-cellsthey have receptor proteins on it's surface that bind to complementary antigens. (presented to it by phagocytes)
- 4what do T-helper cells do (2)1. release chemical signals that activate phagocytes
2. activate B-cells which secrete antibodies - 5what do cytotoxic T-cells dokill abnormal and foreign cells
- 6what do B-cells do, and what is it's structure like(2)-type of WBC
1. covered with antibodies so can join with antigens to make antigen-antibody complexes
2. each B-cell has different shaped antibodies so different ones bind to different antigens - 73. how do T-cells activate B-cells, which divide into plasma cells (3)1. antibody binds to complimentary antigen
2. this & help of t-helper cell activates B-cell. -AKA clonal selection
3. Bcell divides into plasma cells - 8what are plasma cells, and what are they also knaown as-clones of B-cells
-monoclonal antibodies - 94. how do plasma cells make more antibodies to a specific antigen1. plasma cells secrete loads of antibodies to make loads of antigen-antibody complexes
2. agglutination occurs- antibodies have 2 binding sites , so 2 pathogens can bind to it at the same time so pathogens become clumped together.
3. phagocytes bind to antibodies and phagocytose many pathogens at once, destroying them. antigen carried into the body - 10what is the cellular responseThe T-cells and other immune system cells that they interact with eg. phagocytes
- 11what is the humoral responseB-cells, clonal selection and the production of monoclonal antibodies
- 12what is the similarity between the humoral and cellular responseboth remove pathogens from the body.
both help eachopther- eg. t-cells activate b-cells making it easier for phagocytes to engulf them. - 13definition of primary responsewhan an antigen enters the body for the first time, it activates the immune system
- 14explain the primary immune response (4)1. slow response because there arent many B-cells
2. body produces enough of the right amount of to overcome infection. meanwhile patient suffers symptoms
3. after exposed to antigen, t&b cells produce memory cells. they remain in the body for long. they remember the specific antibodies and antigens if ir comes round a second time.
5. patient is now immune- immune system can respnd quickly to second infection - 15definition of secondary responseif same pathogen enters the body again , the immune system will produce a quicker, stronger immune response
- 16explain the secondary response (2)1.clonal selection occurs faster.
memory B-cells-divide into plasma cells
memory t-cells kill the cell carrying the antigen
2. secondary response gets rid of the pathogen before you show any symptoms - 17what do vaccines docontain antigens which cause body to produce memory cells against a pathogen without causing disease- immune without symptoms
- 18what is herd immunityvaccines protect individals who havent been vaccinated because most of the population has been vaccinated so they reduce the occurence of disease
- 19what do vaccines always contain and in what forms can they be injected into the bodyantigens
dead/weakened/free/attached - 20in what 2 ways can people be vaccinatedinjected
orally - 21what are the 2 disadvantages of vaccines taken in orally-broken down by enzymes in the gut
-molecules too large to be absorbed in the blood. - 22why are booster vaccines usedgiven later on to make sure that memory cells are produced.
- 23definition of antigenic variationdifferent antigens are formed due to changes in the genes of a pathogen.
- 24how does antigenic variation work1. when infected a second time the memory cells from the first injection won't recognise the different antigens.
2. so immune system must start from scratch and carry out a primary response.
3. primary response takes along time so you get ill again
4. AV makes it harder to develop vaccines against some pathogens - 25how antigenic variation affects the production of vaccines to prevent people catching influenza1. influenza vaccine changes each year because antigens chsnge regularly
2. memory cells wont recognse the new strain
3. new vaccinea are developed and most effective is chosen each year
4. governments implement a programme using the most suitable one - 26what is active immunity and explain the 2 types-immune system makes it's own antibodies after being stimulated by an antigen
1. natural- become immune after catching a disease
2. artificial- become immune after a vaccination - 27what is passive immunity and what are the 2 types-being given antibodies made by a different organism
1. natural- when a baby becomes immune from antibodies from the mother- placenta and breast milk
2. artificial- become immune after being injected with a different organism - 28differences between active and passive immunity (4)
- 29how can you use monoclonal antibodies to target a drug to cancer cells1. monoclonal antibodies are made against antigens specific to cancer cells
2. anti-cancer drug is attached to antibodies
3. antibodies bind to antigens on cancer cells because their binding sites have complimentary shapes.
4. this delivers the anti-cancer drug to the cells - 30how can monoclonal antibodies be used to target pregnancy testing-preg tests detect the hormone hCG in the urine
1. application area contains hCG antibodies(blue)
2. urine applied, hCG binds to antibody = antigen-antibody complex
3. urine moves up the stick carrying sny beads
4. strip contains antibodies to hCG (immobilised)
5. if hCG is present, the strip turns blue because the immobilised antibody binds to any hCG - 31what does the ELISA test detect and how does it work1. ELISA detects if you have any specific antibodies to antigens
2. antibody is used which has an enzyme attached to it. the enzyme reacts with a substrate to cause a colour change
3. if there is a colour change it shows there is a certain antigen to antibody - 32how can you use the ELISA test to see if a patient posseses antibodies to the HIV virus (4)-indirect ELISA test can be done
1. HIV virus is in the bottom of the well in a well plate
2. the patients blood plasma is added which contains several different antibodies. Any specific antiG bind to antiB. Then well is washed out to remove unbound antibodies
3. secondary antibody with a specific enzyme attached to it is added. secondary antibody binds to HIV antibody. well is washed out again
4. solution added to well. it contains a substrate. this reacts with enzyme to produce a coloured product. if solution changes colour, their blood is infected by HIV - 33what is the difference between HIV and AIDSHIV is the virus that causes AIDS. HIV affects the immune system. AIDS is where the immune system deteriorates and then eventually fails.
- 34what cells does HIV infect and whyt-helper cells- which act as host cells.
people with HIV develop AIDS when the number of T-cells in their body largely decrease. - 35explain the structure of HIV(4)-spherical structure
1. core- contains genetic info& proteins eg. reverse transcriptase
2. protein coating "capsid"
3. extra outer layer "envelope"
4. (sticking out of the envelope)- lots of copies of an attachment protein - helps HIV attach to host t-helper cell - 36explain how HIV replcates inside it's host's t-helper cells (6)1. attachment protein attaches to receptor molecule on cell membrane of host t-helper cell
2. capsid released into cell, releasing genetic material into cytoplasm
3. reverse transcriptase used to make a complimentary strand of DNA from the viral RNA template
4. double stranded DNA is made &inserted into human DNA
5. host cell enzymes used to make viral proteins from viral DNA found in humans
6. viral proteins assembled into new viruses which bud from the cell and go on to infect other cells. - 37what kinds of illnesses can AIDS lead to and how (2)1. minor infections of mucous membranes and respiratory infections
2. number of immune system cells decrease= diarrhoea, tb - 38why don't antibiotics work against viruses(4)1. antibiotics target bacterial enzymes and ribosomes to kill bacteria
2. bacterial enzymes and ribosomes are different to human ones and antibiotics are only deigned for humans
3. viruses dont have their own enzymes and ribosomes- they use the host's cells. so antibiotics cant inhibit them because they dont target human processes.
4. most antiviral drugs target virus specific enzymes . human cells dont use this enzyme so drugs can be deigned to inhibit it without affecting the hot cell. these drugs are called reverse-transcriptase inhibitors - 39because there is no cure for HIV what can be done instead to treat it (2)1. anti-viral drugs slow down the progression of HIV and AIDS
2. reduce the spread through unprotected sexual intercourse and HIV-positive mother to her foetus- take anti-viral drugs during pregnancy
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- AS level Biology FlashCards sobre module 2C, criado por zahra Abbas em 02-06-2017.
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- zahra Abbas
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