1.4: Biotechnology in Health and Medicine

Question 1

What is clonal selection?

Answer 1

specific antigen (on the surface of the pathogen) binds to the antibody receptors on the surface of the lymphocyte. one receptor for one antigen.

Question 2

What are plasma cells?

Answer 2

Type of B-lymphocyte that produces and secretes antibodies of a specific type (monoclonal antibodies)

Question 3

what is agglutination?

Answer 3

antibodies with multiple antigen receptor sites so can ‘glue’ many pathogens together

Question 4

What is the plasma cell ultrastructure?

Answer 4

plasma cells produce protein antibodies so contain a large RER and Golgi body

Question 5

What is the antibody structure?

Answer 5

antibodies are made of proteins in a specific quaternary shape and are complementary to only one antigen.

Question 6

What is clonal expansion (mitosis)?

Answer 6

selected lymphocyte undergoes mitosis so all thee antibodies produced by the cell will be genetically identical in shape and structure

Question 7

What is neutralisation?

Answer 7

antibodies binding to specific toxins to prevent the toxins from entering cells

Question 8

What is the definition of monoclonal antibodies?

Answer 8

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).

Question 9

Who developed the technique of MaB?

Answer 9

Milstein and Kohler in 1975

Question 10

What is the first stage of the monoclonal antibody production?

Answer 10

• A mouse is injected with a specific antigen, which stimulates the production of specific B lymphocytes to make antibodies specific to the antigen

Question 11

What is the second stage of monoclonal antibody production?

Answer 11

• 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.

Question 12

Why are B lymphocytes fused with to create growth?

Answer 12

myeloma cells (tumour) called hybridoma cells

Question 13

What is the third stage of monoclonal antibody production?

Answer 13

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.

Question 14

what is the forth stage of monoclonal antibody production?

Answer 14

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.

Question 15

what chemical is used to allow fusion with lymphocytes and myeloma?

Answer 15

A fusogen e.g. polyethylene glycol

Question 16

How are unfused myeloma cells prevented from growing in addition to the desired hybridoma cells?

Answer 16

Grow cells in a special culture that only supports hybridoma growth

Question 17

What would be used as an antigen to produce monoclonal antibodies for a pregnancy testing kit?

Answer 17

Human Chorionic gonadotrophin (HCG hormone)

Question 18

What are the problems with using mAb derived from animals?

Answer 18

• 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

Question 19

What can mAb be used for?

Answer 19

pregnancy tests, covid tests

Question 20

How does a pregnancy test work?

Answer 20

• ‘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

Question 21

why do free antibodies bind to hCG?

Answer 21

because they have free antigen binding sites, these are complementary and specific to the hCG hormone

Question 22

how does the antigen-antibody complex move along the test strip?

Answer 22

capillary action

Question 23

why does the antigen -antibody complex get stopped in the test zone of pregnant women?

Answer 23

The test zone contain fixed mAb so they can’t move

Question 24

why is a blue line produced in the test strip of pregnant women?

Answer 24

the binding of the hCG hormone to the mAb produces a coloured pigment which creates the line

Question 25

why is no blue line produced in the test strip on non-pregnant women?

Answer 25

They don’t have hCG so no colour will be produced as the hCG doesn’t bind to the mAb

Question 26

What is the purpose of the Control Strip?

Answer 26

to check that the test is working

Question 27

How is the blue colour produced?

Answer 27

the enzyme react with dye molecules to produce a coloured line.

Question 28

What is a biosensor?

Answer 28

A device that uses a biological molecule to detect a chemical compound

Question 29

What does a biosensor consist of?

Answer 29

a biological recognition layer and a transducer

Question 30

what can a biological recignition layer be?

Answer 30

• an enzyme
• antibody
• membrane component
• an organelle
• prokaryotic/eukaryotic cell
• living tissues

Question 31

What is the basis of the sensor?

Answer 31

when two biological molecules interact, there are measurable physical or chemical changes

Question 32

what is a transducer?

Answer 32

a device that converts energy from one form to another, typically a signal in one form of energy to a signal in another

Question 33

what are the bio components immobilised in a biosensor?

Answer 33

so these changes can be measured accurately - close to the transducer

Question 34

What is meant by a potentiometric electrode, give an example?

Answer 34

doesn’t have any voltage applied
- pH electrode

Question 35

What is meant by a amperometric electrode, give an example?

Answer 35

Have a constant applied voltage
- Oxygen electrode

Question 36

what is the biological layer used for?

Answer 36

• sensitivity
• responsible for sensitivity
• produces a biochemical signal

Question 37

How does the transducer work?

Answer 37

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

Question 38

what biological recognition layer is used for blood glucose levels and what is it called?

Answer 38

an enzyme called glucose oxidase

Question 39

What reaction does glucose oxidase catalyse?

Answer 39

glucose + oxygen –> gluconic acid + hydrogen peroxide

Question 40

Where is hydrogen peroxide oxidised?

Answer 40

at a catalytic platinum electrode.

Question 41

How does the catalytic platinum electrode work in biosensors?

Answer 41

by recognising the number of electron transfers, and this electron flow is proportional to the number of glucose molecules present in the blood.

Question 42

what is a microchip biosensor?

Answer 42

small, portable transducer which uses a microchip

Question 43

what can the microchip biosensor be used to measure?

Answer 43

blood glucose concentration in the blood of diabetic

Question 44

How does the microchip biosensor work for diabetics|?

Answer 44

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.

Question 45

How does a biosensor work - step 1 and 2?

Answer 45

• only glucose molecules are allowed through the partially permeable membrane
• these molecules move through the process of facilitated diffusion

Question 46

How does a biosensor work - step 3 and 4?

Answer 46

• on the biological recognition layer there are molecules of glucose oxidase
• the glucose binds to the enzymes active site because there shapes are complimentary

Question 47

How does a biosensor work - step 5 and 6?

Answer 47

• 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.

Question 48

What are the advantages of using the device for diabetics?

Answer 48

• 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