2.4 Stem Cell Dilemmas

A free GCSE Biology lesson for AQA (8461) from OBA School: therapeutic cloning, and weighing up the benefits, risks and ethical issues of using stem cells. Watch the video, read the explanation and worked examples, then try the revision questions. You can work through the full lesson, with every video, practice quizzes and printable worksheets with mark schemes, in our free online course.

What you will learn

• Describe the process of therapeutic cloning and explain why it avoids rejection
• Describe the potential benefits of stem cell treatments
• Describe the practical risks and the ethical and religious objections
• Tell facts from opinions and evaluate arguments to reach a balanced conclusion

Key words

• Therapeutic cloning: Making an embryo with the same genes as a patient, so that its stem cells can be used to treat that patient.
• Rejection: When the immune system attacks cells or tissue from another person because it recognises them as foreign.
• Ethics: Deciding what is morally right or wrong.
• Evaluate: Weigh up the evidence for and against, then give a supported conclusion.

Therapeutic cloning

Cells from another person are seen as foreign by the immune system and may be rejected. In therapeutic cloning, scientists make an embryo with the same genes as the patient, so the stem cells taken from it are not rejected.

Key fact: Stem cells made this way are genetically identical to the patient, so the patient’s immune system does not attack them, and the patient does not need to take drugs to suppress the immune system.

Benefits and risks

• could treat conditions with no current cure, such as paralysis and type 1 diabetes; Risks and problems stem cells grown in the lab could carry a viral infection into the patient
• could replace damaged tissue, e.g. after a heart attack; Risks and problems stem cells that keep dividing could form a tumour (cancer)
• therapeutic cloning avoids rejection; Risks and problems cells from another donor may still be rejected
• could reduce waiting lists for organ donors; Risks and problems treatments are expensive and many are still unproven
• spare embryos from fertility treatment would otherwise be destroyed; Risks and problems progress has been slow; few treatments are in routine use

Ethical and religious issues

Collecting embryonic stem cells destroys the embryo. People hold very different views about this.

• Against: some people believe an embryo is a potential human life from fertilisation and should not be used or destroyed. Some religions teach this. Others worry that the research could be misused, e.g. for reproductive cloning.
• For: others argue that an embryo a few days old is a tiny ball of cells with no nervous system, and that easing the suffering of living patients matters more. Many embryos used would otherwise be thrown away.
• The law: in the UK, research on human embryos is allowed only with a licence from a government regulator, and embryos may only be used up to 14 days old.

Scientists can now reprogramme some adult body cells so that they behave like embryonic stem cells (induced stem cells). This may reduce the need for embryos, but these cells are still being studied.

How to answer “evaluate” questions

1. Give arguments for (benefits).

2. Give arguments against (risks, ethical or religious objections, cost).

3. Use any data you are given.

4. Finish with a conclusion that says which side you think is stronger, and why.

Worked example: fact or opinion?

“Bone marrow transplants are used to treat leukaemia.” This can be checked: a fact.
“It is wrong to use human embryos in research.” This is a belief that people disagree about: an opinion (an ethical judgement).

Answer: science can answer “can we?”; ethics asks “should we?”

Worked example: survey data

In a survey of 1500 adults, 58% supported embryonic stem cell research for treating disease.
Number who supported it = 0.58 × 1500 = 870

Answer: 870 people

Common mistakes

• Saying therapeutic cloning makes a baby. It makes an early embryo only, as a source of stem cells.
• Only giving one side in an “evaluate” question. You need both sides and a conclusion.
• Writing “it is unethical” without saying why some people think so (e.g. the embryo is destroyed).
• Saying stem cells from therapeutic cloning are rejected. They have the patient’s genes, so they are not.

Revision questions

Try these, then check your answers below each one.

Question 1. In therapeutic cloning, the embryo produced has the same genes as which person? (Choose from: The egg donor, The patient, The doctor, A random donor.)

Answer: The patient

Working: The nucleus comes from the patient’s body cell, so the embryo’s cells have the patient’s genes.

Question 2. True or false? Stem cells from therapeutic cloning are unlikely to be rejected by the patient’s immune system.

Answer: True

Working: True. They are genetically identical to the patient.

Question 3. Which is a risk of using stem cells grown in a lab to treat a patient? (Choose from: They could transfer a viral infection, They always cause rejection, They cannot divide, They make the patient’s blood group change.)

Answer: They could transfer a viral infection

Working: Lab-grown stem cells could carry a viral infection into the patient (and could form tumours).

Related lessons

• Previous lesson: 2.3 Stem Cells
• Next lesson: 3.1 Tissues and Organs
• In this chapter: 2.1 Cell Division
• In this chapter: 2.2 Growth and Differentiation

Continue in the full course

This lesson is section 2.4 (AGCBH0204) of our free GCSE Biology course for AQA. In the full course you get every video for this section, a self-marking practice quiz, a printable worksheet with a mark scheme, chapter tests, and your progress saved. Go to the full GCSE Biology course.