GCSE Biology revision

Producing monoclonal antibodies

Monoclonal antibodies (biology only) (HT only)

AQA 4.1.1.1

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AQA student objectives

Learning pathway

All · Most · Some

ALL 🎯

Identify and describe Why Drug Discovery Matters, Sources of Drugs: Plants and Microorganisms and The Discovery of Penicillin in the context of producing monoclonal antibodies.

MOST 🎯🎯

Explain the relationships between Why Drug Discovery Matters, Sources of Drugs: Plants and Microorganisms and The Discovery of Penicillin and how they contribute to producing monoclonal antibodies.

SOME 🎯🎯🎯

Apply and analyse knowledge of Why Drug Discovery Matters, Sources of Drugs: Plants and Microorganisms and The Discovery of Penicillin to interpret unfamiliar information about producing monoclonal antibodies.

Revision summary

Key knowledge

Read on screen, then print for Cornell-style active revision.

Why Drug Discovery Matters

New drugs are needed to treat known diseases that currently have no cure, such as HIV.
Antibiotic resistance has made many existing treatments ineffective, creating an urgent need for substitute drugs.
Advances in technology allow scientists to find better treatments to replace older, less effective ones.
Drug discovery is also essential for tackling newly emerging diseases that scientists have not encountered before.

1. Why Drug Discovery MattersAQA

Notes

New drugs are needed to treat known diseases that currently have no cure, such as HIV.
Antibiotic resistance has made many existing treatments ineffective, creating an urgent need for substitute drugs.
Advances in technology allow scientists to find better treatments to replace older, less effective ones.
Drug discovery is also essential for tackling newly emerging diseases that scientists have not encountered before.

Sources of Drugs: Plants and Microorganisms

Historically, most drugs were extracted from plants and microorganisms rather than being synthesised in a laboratory.
Digitalis (digoxin) is extracted from the leaves of the foxglove plant and is used to stimulate heart muscle and regulate heart rate.
Aspirin is derived from willow tree bark, with salicylic acid as its active component, and is used to reduce pain and inflammation.
In modern times, many drugs are synthesised directly by chemists rather than being extracted from natural sources.

2. Sources of Drugs: Plants and MicroorganismsAQA

Notes

Historically, most drugs were extracted from plants and microorganisms rather than being synthesised in a laboratory.
Digitalis (digoxin) is extracted from the leaves of the foxglove plant and is used to stimulate heart muscle and regulate heart rate.
Aspirin is derived from willow tree bark, with salicylic acid as its active component, and is used to reduce pain and inflammation.
In modern times, many drugs are synthesised directly by chemists rather than being extracted from natural sources.

The Discovery of Penicillin

Penicillin was discovered accidentally by Alexander Fleming when he returned from holiday to find mould growing on his Staphylococcus petri dishes.
A clear, lysed (bacteria-free) zone around the mould indicated that it had secreted a substance inhibiting bacterial growth.
The mould was later identified as a strain of Penicillium, and the substance it produced became known as penicillin.
Fleming found that his 'mould juice' was capable of killing a wide range of harmful bacteria, making it a landmark discovery in medicine.

3. The Discovery of PenicillinAQA

Notes

Penicillin was discovered accidentally by Alexander Fleming when he returned from holiday to find mould growing on his Staphylococcus petri dishes.
A clear, lysed (bacteria-free) zone around the mould indicated that it had secreted a substance inhibiting bacterial growth.
The mould was later identified as a strain of Penicillium, and the substance it produced became known as penicillin.
Fleming found that his 'mould juice' was capable of killing a wide range of harmful bacteria, making it a landmark discovery in medicine.

Key Criteria for Drug Development

Before a drug can be approved for use, it must be tested to ensure it is both effective against disease and safe for patients.
Dosage must be carefully determined, as too low a dose renders the drug ineffective while too high a dose can cause dangerous toxicity.
Toxicity testing checks for harmful side effects, including both short-term effects and long- term effects such as an increased risk of cancer.
Efficacy refers to how effective the drug is at treating the disease, and a drug must show significant benefit before it can be approved.

4. Key Criteria for Drug DevelopmentAQA

Notes

Before a drug can be approved for use, it must be tested to ensure it is both effective against disease and safe for patients.
Dosage must be carefully determined, as too low a dose renders the drug ineffective while too high a dose can cause dangerous toxicity.
Toxicity testing checks for harmful side effects, including both short-term effects and long- term effects such as an increased risk of cancer.
Efficacy refers to how effective the drug is at treating the disease, and a drug must show significant benefit before it can be approved.

Preclinical Testing: Stage 1

Preclinical testing is carried out entirely within the laboratory and does not involve humans or animals at this stage.
Testing begins with computer modelling and in vitro testing, meaning experiments are conducted outside of a living body, for example in a test tube.
The aim of preclinical testing is to confirm that the drug is sufficiently safe and effective before progressing to animal or human trials.

5. Preclinical Testing: Stage 1AQA

Notes

Preclinical testing is carried out entirely within the laboratory and does not involve humans or animals at this stage.
Testing begins with computer modelling and in vitro testing, meaning experiments are conducted outside of a living body, for example in a test tube.
The aim of preclinical testing is to confirm that the drug is sufficiently safe and effective before progressing to animal or human trials.

Animal Testing: Stage 2

After successful preclinical testing, the drug is tested on animals to further assess its safety and effectiveness.
Animal testing is legally required in the UK before any new drug can be introduced to human trials.
This stage raises significant ethical concerns, as many people strongly oppose the use of animals in scientific research.
If the drug is found to be unsafe or ineffective at any stage, the clinical trial is immediately halted.

6. Animal Testing: Stage 2AQA

Notes

After successful preclinical testing, the drug is tested on animals to further assess its safety and effectiveness.
Animal testing is legally required in the UK before any new drug can be introduced to human trials.
This stage raises significant ethical concerns, as many people strongly oppose the use of animals in scientific research.
If the drug is found to be unsafe or ineffective at any stage, the clinical trial is immediately halted.

Phase 1 Clinical Trials: Stage 3

Phase 1 involves testing the drug on a very small number of healthy human volunteers, typically around 15 to 20 people.
Very low doses are used initially, and the dose is gradually increased to find the optimum safe level — a process known as dose titration.
The primary goal of Phase 1 is to confirm that the treatment is safe in humans and to identify the best dose to use going forward.

7. Phase 1 Clinical Trials: Stage 3AQA

Notes

Phase 1 involves testing the drug on a very small number of healthy human volunteers, typically around 15 to 20 people.
Very low doses are used initially, and the dose is gradually increased to find the optimum safe level — a process known as dose titration.
The primary goal of Phase 1 is to confirm that the treatment is safe in humans and to identify the best dose to use going forward.

Phase 2 and Phase 3 Clinical Trials: Stages 4 & 5

Phase 2 tests the efficacy of the drug in actually treating patients, involving a larger group of around 20 to 150 participants.
Phase 3 compares the new drug against existing treatments in large-scale trials involving hundreds or even thousands of participants.
Larger sample sizes improve the reliability of results, as they are more representative of the wider population.
Phase 3 trials are often double-blind, meaning neither the patient nor the scientist knows whether the patient is receiving the drug or a placebo.
A placebo is a substance that contains no active drug ingredients but is identical in appearance, taste, and dosage to the real drug, reducing bias in the trial.

8. Phase 2 and Phase 3 Clinical Trials: Stages 4 & 5AQA

Notes

Phase 2 tests the efficacy of the drug in actually treating patients, involving a larger group of around 20 to 150 participants.
Phase 3 compares the new drug against existing treatments in large-scale trials involving hundreds or even thousands of participants.
Larger sample sizes improve the reliability of results, as they are more representative of the wider population.
Phase 3 trials are often double-blind, meaning neither the patient nor the scientist knows whether the patient is receiving the drug or a placebo.
A placebo is a substance that contains no active drug ingredients but is identical in appearance, taste, and dosage to the real drug, reducing bias in the trial.

Double-Blind Trials and Reducing Bias

In a double-blind trial, the patient does not know whether they are receiving the actual drug or a placebo, preventing psychological bias.
The scientist administering the treatment also does not know which substance is being given, further reducing experimental bias.
Reducing bias in this way increases the reliability and validity of the clinical trial results.

9. Double-Blind Trials and Reducing BiasAQA

Notes

In a double-blind trial, the patient does not know whether they are receiving the actual drug or a placebo, preventing psychological bias.
The scientist administering the treatment also does not know which substance is being given, further reducing experimental bias.
Reducing bias in this way increases the reliability and validity of the clinical trial results.

The Drug Development Process: Key Takeaways

The full process of drug development, from discovery to approval, can take many years and cost billions of pounds.
Only a very small percentage of drugs successfully pass through all five stages of clinical trials and receive approval for national use.
Drug development remains critically important as antibiotic resistance continues to grow and new diseases continue to emerge.
Understanding the five stages — preclinical testing, animal testing, Phase 1, Phase 2, and Phase 3 — is a key requirement of the AQA GCSE Biology specification.

10. The Drug Development Process: Key TakeawaysAQA

Notes

The full process of drug development, from discovery to approval, can take many years and cost billions of pounds.
Only a very small percentage of drugs successfully pass through all five stages of clinical trials and receive approval for national use.
Drug development remains critically important as antibiotic resistance continues to grow and new diseases continue to emerge.
Understanding the five stages — preclinical testing, animal testing, Phase 1, Phase 2, and Phase 3 — is a key requirement of the AQA GCSE Biology specification.