1.4: Biotechnology in Health and Medicine Flashcards
What is clonal selection?
specific antigen (on the surface of the pathogen) binds to the antibody receptors on the surface of the lymphocyte. one receptor for one antigen.
What are plasma cells?
Type of B-lymphocyte that produces and secretes antibodies of a specific type (monoclonal antibodies)
what is agglutination?
antibodies with multiple antigen receptor sites so can ‘glue’ many pathogens together
What is the plasma cell ultrastructure?
plasma cells produce protein antibodies so contain a large RER and Golgi body
What is the antibody structure?
antibodies are made of proteins in a specific quaternary shape and are complementary to only one antigen.
What is clonal expansion (mitosis)?
selected lymphocyte undergoes mitosis so all thee antibodies produced by the cell will be genetically identical in shape and structure
What is neutralisation?
antibodies binding to specific toxins to prevent the toxins from entering cells
What is the definition of monoclonal antibodies?
these are antibodies against one specific antigen (epitope). They are produced by descendants of a specific B cell. One type of antibody is produced for one type of antigen (epitope).
Who developed the technique of MaB?
Milstein and Kohler in 1975
What is the first stage of the monoclonal antibody production?
- A mouse is injected with a specific antigen, which stimulates the production of specific B lymphocytes to make antibodies specific to the antigen
What is the second stage of monoclonal antibody production?
- after 2-3 weeks, the mouse is killed and the spleen is removed. B lymphocytes are washed out of the spleen and separated by centrifugation.
Why are B lymphocytes fused with to create growth?
myeloma cells (tumour) called hybridoma cells
What is the third stage of monoclonal antibody production?
Hybridoma cells are formed which divide indefinitely when grown.
- individual hybridoma cells are added into separate wells in a multi well culture dish by diluting the culture medium.
what is the forth stage of monoclonal antibody production?
After a week each cell will have divided to produce a clone of identical cells. A sample from each cell is tested for MAb
- antibody will then be extracted and purified.
what chemical is used to allow fusion with lymphocytes and myeloma?
A fusogen e.g. polyethylene glycol
How are unfused myeloma cells prevented from growing in addition to the desired hybridoma cells?
Grow cells in a special culture that only supports hybridoma growth
What would be used as an antigen to produce monoclonal antibodies for a pregnancy testing kit?
Human Chorionic gonadotrophin (HCG hormone)
What are the problems with using mAb derived from animals?
- animal antibodies may be recognised as ‘foreign’ by the immune system. mAb may be destroyed by the immune system and removed before an effect occurs
- Immune complexes can damage organs such as the kidneys
- ethical issues around killing mice to produce them
What can mAb be used for?
pregnancy tests, covid tests
How does a pregnancy test work?
- ‘dipstick’ is dipped into urine sample
- hcg hormone will attach to the first mAb on the stick
- rinse stick in water
- ‘dipstick’ is dipped into second mAb with enzyme attached
- Enzyme attached to antibody will only attach to dipstick if hCg is present
- rinse the stick in water again
- dipstick is dipped into enzyme substrate
- if hCG present blue colour will appear as the substrate will bind to the enzyme
why do free antibodies bind to hCG?
because they have free antigen binding sites, these are complementary and specific to the hCG hormone
how does the antigen-antibody complex move along the test strip?
capillary action
why does the antigen -antibody complex get stopped in the test zone of pregnant women?
The test zone contain fixed mAb so they can’t move
why is a blue line produced in the test strip of pregnant women?
the binding of the hCG hormone to the mAb produces a coloured pigment which creates the line
why is no blue line produced in the test strip on non-pregnant women?
They don’t have hCG so no colour will be produced as the hCG doesn’t bind to the mAb
What is the purpose of the Control Strip?
to check that the test is working
How is the blue colour produced?
the enzyme react with dye molecules to produce a coloured line.
What is a biosensor?
A device that uses a biological molecule to detect a chemical compound
What does a biosensor consist of?
a biological recognition layer and a transducer
what can a biological recignition layer be?
- an enzyme
- antibody
- membrane component
- an organelle
- prokaryotic/eukaryotic cell
- living tissues
What is the basis of the sensor?
when two biological molecules interact, there are measurable physical or chemical changes
what is a transducer?
a device that converts energy from one form to another, typically a signal in one form of energy to a signal in another
what are the bio components immobilised in a biosensor?
so these changes can be measured accurately - close to the transducer
What is meant by a potentiometric electrode, give an example?
doesn’t have any voltage applied
- pH electrode
What is meant by a amperometric electrode, give an example?
Have a constant applied voltage
- Oxygen electrode
what is the biological layer used for?
- sensitivity
- responsible for sensitivity
- produces a biochemical signal
How does the transducer work?
biological component is immobilised into the surface of the transducer
- it is an electrical device which can measure signals from the biological reaction
- the voltage produced by the reaction is measured
what biological recognition layer is used for blood glucose levels and what is it called?
an enzyme called glucose oxidase
What reaction does glucose oxidase catalyse?
glucose + oxygen –> gluconic acid + hydrogen peroxide
Where is hydrogen peroxide oxidised?
at a catalytic platinum electrode.
How does the catalytic platinum electrode work in biosensors?
by recognising the number of electron transfers, and this electron flow is proportional to the number of glucose molecules present in the blood.
what is a microchip biosensor?
small, portable transducer which uses a microchip
what can the microchip biosensor be used to measure?
blood glucose concentration in the blood of diabetic
How does the microchip biosensor work for diabetics|?
the enzyme glucose oxidase is incorporated into a disposable probe that clips into an electrical device. A drop of blood is placed on the probe.
A readout is produced on the biosensor to indicate blood glucose conc.
How does a biosensor work - step 1 and 2?
- only glucose molecules are allowed through the partially permeable membrane
- these molecules move through the process of facilitated diffusion
How does a biosensor work - step 3 and 4?
- on the biological recognition layer there are molecules of glucose oxidase
- the glucose binds to the enzymes active site because there shapes are complimentary
How does a biosensor work - step 5 and 6?
- the products of this reaction are called gluconic acid and hydrogen peroxide
- the transducer converts the electron conc. into an electrical signal, which are proportional.
What are the advantages of using the device for diabetics?
- accurate/sensitive
- rapid
- portable
- quantitative
- re-usable
- no need to go to clinic for readings
- allows correct doses of insulin
- only a small amount of blood needed
