Antibodies & Vaccination (Cambridge (CIE) AS Biology): Flashcards
Exam code: 9700
1/390Still learning
Know0
- FrontAntibodies
Define antibody.
Was this flashcard helpful?
Cards in this collection (39)
Define antibody.
An antibody is a glycoprotein (immunoglobulin) made by plasma cells that binds specifically to a particular antigen.
Describe the structure of an antibody.
It is made of four polypeptide chains — two heavy and two light chains — held together by disulfide bonds in a Y-shape.
It has two antigen-binding sites.
What is the variable region of an antibody and why is it important?
The variable region has a specific shape that is complementary to one particular antigen, so each antibody binds to only one type of antigen.
Define antigen-antibody complex.
The structure formed when an antibody binds to its specific antigen.
How does having two antigen-binding sites relate to an antibody's function?
An antibody can bind two pathogens at once, clumping them together (agglutination) so that phagocytes can engulf them more easily.
What is the role of the constant region of an antibody?
The constant region allows the antibody to bind to receptors on phagocytes, helping them to recognise and engulf the pathogen.
The variable region of an antibody has a shape that is to a specific antigen.
The variable region of an antibody has a shape that is complementary to a specific antigen.
Define monoclonal antibody.
Antibodies that are all identical because they are produced by cloned cells derived from a single B-lymphocyte, so they bind to one specific antigen.
Define hybridoma.
A cell made by fusing a B-lymphocyte with a tumour (myeloma) cell; it produces antibodies and can divide indefinitely.
Outline the hybridoma method for producing monoclonal antibodies.
An animal (e.g. a mouse) is injected with an antigen so it makes B-lymphocytes that produce the required antibody.
These B-lymphocytes are fused with tumour (myeloma) cells to form hybridoma cells.
Hybridomas making the required antibody are selected and cultured.
They divide to produce large amounts of identical monoclonal antibodies.
Why are B-lymphocytes fused with tumour (myeloma) cells?
B-lymphocytes do not divide well in culture, but tumour cells divide rapidly and indefinitely, so the hybridoma can both make antibody and keep dividing.
A hybridoma is made by fusing a B-lymphocyte with a cell.
A hybridoma is made by fusing a B-lymphocyte with a tumour cell.
Why are the antibodies produced described as monoclonal?
They are all identical and specific to one antigen, because they are made by clones of a single hybridoma cell.
Outline the principle of using monoclonal antibodies in the diagnosis of disease.
A monoclonal antibody is made to bind specifically to an antigen linked to the disease.
Attaching a marker (e.g. a dye or radioactive label) then shows whether or where that antigen is present.
How can monoclonal antibodies be used to locate cancer cells or blood clots?
The antibodies are made to bind to antigens on the target cells and carry a radioactive or fluorescent marker, so the site can be detected by scanning.
Outline the principle of using monoclonal antibodies in the treatment of disease.
They are made to bind specifically to a target (e.g. antigens on cancer cells), so they can block its activity or deliver a drug directly to it.
What is a "magic bullet"?
A monoclonal antibody with a drug or toxin attached that delivers the drug only to target cells (e.g. cancer cells), reducing damage to healthy cells.
Why do monoclonal antibody treatments cause fewer side effects than some other treatments?
Because each antibody binds to only one specific antigen, they target only the diseased cells, so healthy cells are largely unaffected.
Monoclonal antibodies are highly specific because each one binds to a single type of .
Monoclonal antibodies are highly specific because each one binds to a single type of antigen.
Define active immunity.
Immunity gained when the body's own immune system is stimulated by an antigen to make its own antibodies and memory cells.
Define passive immunity.
Immunity gained by receiving antibodies made by another organism; no memory cells are made, so it is short-lived.
What is the difference between natural and artificial immunity?
Natural immunity is gained through normal life, e.g. an infection or antibodies from the mother.
Artificial immunity is gained through medical intervention, e.g. vaccination or an injection of antibodies.
Give an example of natural active immunity.
Making your own antibodies and memory cells after catching and recovering from an infection.
Give an example of artificial passive immunity.
Being injected with antibodies made by another organism, e.g. anti-venom or tetanus antibodies.
Why is passive immunity short-lived while active immunity is long-lasting?
Passive immunity provides only ready-made antibodies and no memory cells, so it ends when they break down.
Active immunity produces memory cells, giving long-term protection.
Immunity gained by receiving ready-made antibodies from another organism is called immunity.
Immunity gained by receiving ready-made antibodies from another organism is called passive immunity.
Give an example of natural passive immunity.
A baby receiving antibodies from its mother across the placenta or in breast milk.
Define vaccine.
A preparation containing antigens that stimulates the immune system to produce antibodies and memory cells without causing the disease.
How does a vaccine provide long-term immunity?
The vaccine's antigens stimulate a primary immune response, producing antibodies and memory cells.
If the real pathogen later enters, memory cells trigger a rapid secondary response, destroying it before symptoms develop.
What do vaccines contain?
Antigens, e.g. from a weakened (attenuated), dead, or otherwise modified pathogen, or purified antigen molecules.
Vaccines work because they contain that stimulate an immune response.
Vaccines work because they contain antigens that stimulate an immune response.
Why doesn't a vaccine make you ill, even though it triggers an immune response?
It contains only antigens or weakened/dead pathogens, which cannot cause the disease but still stimulate the immune system.
True or False?
Vaccines contain live, fully active pathogens.
False.
Vaccines contain antigens from dead, weakened or modified pathogens, so they cannot cause the disease.
Define herd immunity.
When a large proportion of a population is immune (e.g. vaccinated), so the pathogen cannot spread easily, protecting even those who are not immune.
How do vaccination programmes control the spread of an infectious disease?
By making most of the population immune, there are fewer people who can catch and pass on the pathogen, so transmission is reduced and outbreaks are prevented (herd immunity).
Why must a high percentage of the population be vaccinated for a programme to work?
So that too few susceptible individuals remain for the pathogen to spread between, breaking the chain of transmission.
When enough people are vaccinated, unvaccinated people are also protected; this is called immunity.
When enough people are vaccinated, unvaccinated people are also protected; this is called herd immunity.
Why can some diseases not be easily controlled by vaccination?
The pathogen's antigens change (antigenic variation), so existing vaccines and memory cells no longer recognise it, e.g. influenza.
How did vaccination lead to the eradication of smallpox?
A worldwide vaccination programme made enough people immune that the virus could no longer spread, so smallpox was eradicated.
Sign up to unlock flashcards
or