Summary Edexcel GCSE Biology Topic 5 - Health, Disease and Development of Medicines
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Edexcel GCSE Biology Topic 1 - Key Concepts in Biology
Edexcel GCSE Biology Topic 2 - Cells and Control
Edexcel GCSE Biology Topic 3 - Genetics
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Monoclonal Antibodies
Monoclonal antibodies are identical antibodies produced by laboratories from a single clone of
immune cells. The cloned immune cells are genetically completely identical. And so, the antibodies
they produce are also identical to each other. Which is perfect - to work properly, we need large
numbers of identical antibodies.
Monoclonal antibodies have a high specificity, which means they can recognise and bind to a single
antigen binding site. This means that they are targeted to a specific antigen, and is a key trait which
makes them useful in diagnosing and treating diseases.
Pregnancy Test Sticks: https://www.youtube.com/watch?v=M3zllm8QbCM
They work by detecting a hormone only produced during pregnancy (only in tiny amounts though).
They have to be very sensitive and use antibodies specially made to match the hormone. They need
large amounts of these identical antibodies that we call monoclonal antibodies.
A pregnancy test detects the
presence of the hCG 'pregnancy'
hormone. HCG is normally only
present in your body if you are
pregnant. Any positive line, no
matter how faint, means your
result is pregnant. Levels of hCG
in your body will increase over
the course of your pregnancy.
Monoclonal antibodies on the
pregnancy test stick bind to the
HCG hormone found in the urine
of pregnant women causing a colour change.
To make large amounts of these antibodies We use lymphocytes. We cannot use normal
lymphocytes to produce them because once they have produced antibodies they cannot divide
(copy themselves) any more.
Stage 1
A particular antigen is injected into a mouse. The mouse produces lymphocytes that make
antibodies against the antigen.
Stage 2
Cancer cells are grown in a culture medium.
Stage 3
The lymphocyte cell from the mouse and the cancer cell are fused together to make a
hybridoma cell.
Hybridoma Cells
They can both divide and make antibodies against the injected antigen.
, Task 3: Gold
Hybridoma cells are needed
to produced monoclonal
antibodies because
lymphocyte cells stop
dividing when they produce
antibodies. Hybridoma cells
continue to divide to produce
identical cells and produce
antibodies
State what monoclonal antibodies are
Monoclonal antibodies are large numbers of antibodies that are identical
Describe what a hybridoma cell is.
A hybridoma cell is a cell formed when you fuse a non-dividing lymphocyte (which is producing
antibodies to a particular antigen) with a cancer cell. These cells continue to divide to produce
identical clones which produce antibodies.
Explain why cancer cells are used in making monoclonal antibodies.
Cancer cells are used because lymphocytes cannot divide after they start to produce antibodies.
This fusion enables the production of clone cells which produces lots of antibodies.
Advantages of using Monoclonal Antibodies Disadvantages of using Monoclonal Antibodies
• Hybridoma serves as an immortal source of • Time consuming project - anywhere between 6
monoclonal antibody. months -9 months.
• Same quality of the antibody is maintained amongst • Very expensive and needs considerable effort to
the different production batches. produce them.
• Highly reproducible and scalable, unlimited production • Small peptide and fragment antigens may not be good
source. antigens-monoclonal antibodies may not recognize
• Speed and sensitivity and specificity of assays. the original antigen.
• Can produce antibodies when needed. • Hybridoma culture may be subject to contamination.
• No need to worry about maintaining the animals. • System is only well developed for mice and rats and
• Antigen or immunogen need not be pure. not for other animals.
• Selection helps to identify the right clones against the • More than 99% of the cells do not survive during the
specific antigen fusion process – reducing the range of useful
antibodies that can be produced against an antigen.
• Ethical issues surrounding the use of mice
,Explain how monoclonal antibodies could be used to identify where a blood clot has formed in a
patient’s brain.
Monoclonal antibodies are produced that match the patient’s platelets. The antibodies are made
radioactive and injected into the patient’s blood. The antibodies will attach to the platelets. A scan
of the patient’s brain will show where the radioactive platelets have clumped together form a clot.
Many people are given drugs (chemotherapy) or ionising radiation (radiotherapy) to kill the cancer
cells.
Cancer drugs can be attached to monoclonal antibodies so that they are delivered just to the cells
that need treating. This reduces the amount of drug needed to kill the cancer cells and reduces the
risk of damaging healthy cells.
Disadvantage
They also expose healthy cells to the drugs or radiation and can often damage them.
Describe how monoclonal antibodies that deliver drugs to kill cancer cells could be produced.
Antigens from the cancer cells are injected into a mouse. Lymphocytes that make antibodies to the
cancer cell antigens are taken from the mouse and fused with a cancer cell to make hybridoma
cells. The hybridoma cells produce monoclonal antibodies to the cancer cell antigens. Drugs that
kill cancer cells are attached to the antibodies.
Explain why using monoclonal antibodies in the treatment of cancer could be better for the
patient than traditional chemotherapy or radiotherapy.
Both chemotherapy and radiotherapy can harm healthy parts of the body. Using monoclonal
antibodies means that there is very little of the harmful drug in the patient's body. They only
attach to cancer cells so that healthy cells are less likely be damaged.
, Cancer treatment - https://www.youtube.com/watch?v=AbmEt_E8kfo
Cancer drugs can encourage your immune system to kill the cancer. In breast cancer, there is a monoclonal
antibody against HER-2. Cancer has evolved to become smart enough to develop an array of escape
mechanisms to trick the immune system into ignoring it as a threat. This includes impersonating normal
body cells and exploiting checkpoint proteins such as PD-1 on T cells in the immune system. T cells seek out
and destroy cancerous cells, but PD-1 helps rein in the T cells so that they don’t go overboard and destroy
healthy cells. However, many cancer cells wear a protein called PD-L1, which can fool T cells into treating
them as normal cells, leaving them to multiply freely. That’s where naked monoclonal antibodies come in:
They can block these checkpoint molecules, allowing T cells to seek out and destroy the cancer cells.
Explain why using monoclonal antibodies that target checkpoint proteins could help treat cancer
Cancer cells can impersonate normal body cells by expressing a protein called PD-L1, which can fool T
cells into treating them as normal cells, leaving them to multiply freely. A monoclonal antibody could
block these checkpoint molecules, allowing T cells to seek out and destroy the cancer cells.
Explain how monoclonal antibodies against HER-2 could help treat breast cancer. What does HER-2 do?
Monoclonal antibodies can also work by latching onto antigens on cancer cells that help cancer cells
proliferate. An example of this is trastuzumab (Herceptin), a monoclonal antibody which is used to target
the HER2 protein, which is overexpressed in breast cancer. Drugs can be attached to this monoclonal
antibody to kill the tumour.
Monoclonal antibodies can target the antigens on cancer cells and can be used in a number of ways:
1. By combining them with an anti-cancer drug which can accurately locate and target only the cancer
cells or avoiding the healthy cells.
2. For detection, they can carry special markers which can show doctors where the cancerous cells
are4 starting to build up.
3. They can be used to trigger the body's own immune system to recognise and kill the cancer cells.
4. They can also be used to identify other diseases, and locate blood clots.
HW
S1 How are monoclonal antibodies used in the diagnosis of some diseases and the treatment of those
diseases?
Monoclonal antibodies can be made radioactive. If the antibodies have been made to attach to cancer cells
or platelets, then a scan will show where the antibodies are and so show where the cancer or blood clot is.
If drugs are attached to the antibodies, these will be delivered to the cancer or platelet cells and so treat
the disease.
E1 During the clotting of blood an enzyme changes one substance into another, which
then forms the clot. Describe how monoclonal antibodies could be made that bind to the enzyme, and
suggest how they could be tested to make sure these monoclonal antibodies are effective in preventing
blood clots in humans.
The human enzyme could be injected into a mouse so that the mouse's body makes antibodies to it. The
lymphocytes that make those antibodies could be extracted from the mouse and used to make hybridoma
cells by fusing them with cancer cells. Monoclonal antibodies from the cells could then be tested on human
blood cell cultures to make sure they prevent the enzyme causing blood clots to form. It would then need
to be tested in clinical trials on people to make sure it is safe.
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