Answers to AQA GCSE Using Monoclonal Antibodies (Biology)

AQA GCSE Using Monoclonal Antibodies (Biology)

Using Monoclonal Antibodies

We have many uses for monoclonal antibodies

1.Pregnancy tests

2.Laboratories use monoclonal antibodies to measure the levels of hormones and other chemicals in blood, or to detect pathogens.

3.Monoclonal antibodies are used in research to locate specific molecules

4.Monoclonal antibodies are used in research to identify specific molecules in a cell or tissue by binding to them with a fluorescent dye.

5. Monoclonal antibodes can be used to treat some diseases. These include cancer where the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. The monoclonal antibody delivers the substance to the cancer cells without harming other cells in the body.

Monoclonal Antibodies

Monoclonal antibodies are lab-made antibodies that all target one specific antigen.

Antigens are molecules usually found on pathogens, cancer cells, or other diseased cells.

Specific targeting: They bind only to the cells with the target antigen, leaving healthy cells mostly untouched.

Given appropiate information, you may have to describe a how a test or treatment works. Some examples are given below.

Pregnancy tests

A pregnancy test contains monoclonal antibodies that bind specifically to the hormone hCG, which is found in the urine of pregnant women.

When the base of the strip is placed into a sample of urine, the urine will soak up the strip.

The hCG within the urine will bind to dye labelled monoclonal antibodies within the reaction zone of the strip.

These dye labelled monoclonal antibodies with hCG will then bind to the immobilised monoclonal antibodies that form part of the test zone to form a blue test line.

Dye labelled Monoclonal antibodies that did not bind to any hCG will bind to immobilised antibodies in the control zone to form a blue control line.

The control line is designed to prove that the test has worked.

The blue line at the test zone if present, will indicate pregnancy.

Using monoclonal antibodies to measure the levels of hormones and other chemicals in blood

Example: measuring a hormone in blood

1.Monoclonal antibodies with a coloured marker are added to the sample.

2.The antibodies bind to the hormone molecules.

3.If the sample contains more hormone, more antibodies bind.

4.This produces a stronger colour change.

5.Instruments then measure how strong the colour is → this tells scientists the amount.

Detecting pathogens

Monoclonal antibodies can be produced that are specific to antigens on pathogens (such as viruses or bacteria).

A marker (dye, coloured bead, enzyme, or fluorescent tag) is attached to these antibodies.

When the labelled antibody is added to a sample (blood, urine, saliva, or a swab):

If the pathogen is present the labelled monoclonal antibody binds to the antigen. The attached dye produces a visible colour / fluorescent signal.

If the pathogen is not present the antibody has nothing to bind to so no signal is produced.

Locating or identifying specific molecules in cells or tissues

Scientists make monoclonal antibodies that are specific to one molecule (e.g., a protein in a cell).

They attach a fluorescent dye to the antibody.

When they add these antibodies to a cell or tissue sample, the antibodies bind only where that molecule is present.

Under a microscope, the dyed areas glow, showing the exact location.

Treating diseases

Treating cancer with monoclonal antibodies:

1.Identify an antigen that is only found on the surface of cancer cells.

2.Produce a monoclonal antibody that binds specifically to that antigen.

3.Attach a treatment substance to the antibody (toxic drug, radioactive particle, or chemical that stops cell division).

4.Inject the antibody into the patient.

5.The antibody binds to the cancer cells, delivering the treatment directly to them.

6.Cancer cells are killed while healthy cells are mostly unaffected.

Ethical considerations of Monoclonal antibodies.

Animal use: Many monoclonal antibodies are initially produced using mice, raising questions about animal welfare.

Cost/access: Treatments can be very expensive, so not everyone can afford them.

Safety risks: Side effects can be serious; some may provoke immune reactions.

Medical priorities: Should limited resources go to expensive monoclonal antibodies treatments or other healthcare needs

Advantages and Disadvantages

Advantages of monoclonal antibodies	Disadvantages of monoclonal antibodies
Specific targeting – They bind only to cells with the target antigen, reducing damage to healthy cells.	Side effects – Can cause fever, rashes, nausea, or severe immune reactions. Sometimes more than expected.
Versatile applications – Can be used for treatment, diagnosis, and prevention of diseases.	Expensive – Manufacturing and treatment costs are very high, limiting access.
Effective in difficult diseases – Helpful in cancers, autoimmune diseases, and some infections.	Complex production – Often requires animals (e.g., mice) and sophisticated labs.
Reduced need for broad treatments – Sometimes fewer side effects than traditional chemotherapy or broad-spectrum drugs (though not always).	Not always widely used – Despite their potential, issues like side effects and cost have slowed widespread adoption.
Detecting diseases – Useful in tests like pregnancy tests or detecting pathogens, making diagnosis quicker and more accurate.	Ethical concerns – Use of animals, and questions about fairness in healthcare resource allocation.