antibodies + vacccines Flashcards
what is an antibody?
protein secreted by plasma cells
state the structure of an antibody?
- quaternary structure: 2 light chains, 2 heavy chains
- variable regions
- constant region
what is a monoclonal antibody?
- antibody with the same tertiary structure
- derived from a single clone of plasma cells
what are variable regions?
antigen binding sites
- have unique teritary structure complimentary to antigen
what are constant regions?
- same on all antibodies
- allows binding to receptors on immune system cels
what causes antigen variability?
- random genetic mutation changes DNA base sequence
- results in different sequence of codons on mRNA
- different primary structure of antigen so H bonds, ionic, disulfide bridges form in different place in tertiary structure
- different shape of antigen
explain how antigen variability affects the incidence of disease
- memory cells no longer complimentary to antigen
- individual not immune so can catch disease more than once
- many varieties of pathogen so difficult to develop vaccine against all antigen types
the main idea to start this question is that the antigen is now a different shape
how do vaccines work?
aka how do vaccines lead to immunity
- vaccines contain dead/inactive form of a pathogen
- triggers primary immune response
- memory cells produced and remain in bloodstream
- secondary response is rapid & produces higher concentration of antibodies
- pathogen destroyed before it causes symptoms
compare passive and active immunity
give examples of both types
active immunity:
- antibodies produce by lymphocytes
- antibodies take 1-2 weeks to appear in blood
- long term effect because memory cells produced
- direct contact with antigen necessary
- natural= e.g. humoral response to infection
- active= vaccination
passive immunity
- antibodies from external source
- antibodies appeear immediately
- short tern affect because no memory cells produced
- direct contact with antigen not necessary
- natural= e.g. antibodies in breast milk/across placenta
- artificial= e.g. injected antibodies for example, antivenom
SIMILARITIES:
BOTH FORMS INVOLVE ANTIBODIES
BOTH CAN BE NATURAL OR ARTIFICIAL
what is herd immunity?
- vaccinating a large proportion of population reduces carriers of pathogen
- protects indivudals who have not been vaccinated
- e.g. protects those with weak immune system
suggests some ethical issue surrounding the use of vaccines
- production may involve use of animals
- potentially dangerous side effects
- clinical tests may be fatal
- people cant be forced to recieve vaccine
what is the function of antibodies?
aka how do antibodies actually work/help?
- agglutination= antibodies bind to antigens to form antigen-antibody complex
- neutralising toxins= neutralise toxins released by pathogen
- preventing viruses from entering host cells
what is agglutination?
- antibodies bind to antigens on pathogens causing them to clump together
- clumps destroyed by phagocytosis
- makes it easier for phagocytes to engulf more pathogens at a time
list some medical uses for monoclonal antibodies?
- pregnancy test
- ELISA test
- targeting drugs to a partiular cell type
explain how pregnancy tests work
- urine applied to specific area of primary antibodies bound to coloured beads
- hCG binds to primary antibody if present forming antigen-antibody complex
- moves up strip carrying bead
practice q
explain why antibody A attaches only to the protein found in (x) specific species?
- antibody A has specific tertiary structure
- complimentary to binding site of protein
give 4 reasons why number of people recieving the vaccine decreased
this q will often be accompanied by a graph, use data from the graph but these points are generally correct
1) decreasing in number of cases of disease
- so parents didnt feel need to vaccinate child
2) vaccination too expensive to distribute
3) parents fearful of dangerous side effects of vaccine
