Gene therapy

Overview

Gene therapy, why an absent or faulty gene can cause disease and why liposomes are sometimes preferred to viral vectors.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is gene therapy?

   Model answer

   Gene therapy is the treatment of a disorder by inserting a functioning copy of a gene into a patient's cells.

2. 2

   Explain why an absent or faulty gene can cause disease.

   Model answer

   The cell cannot make a working copy of the protein the gene codes for, so a reaction is not catalysed or a structure is not built, and the resulting metabolic block produces the symptoms.

3. 3

   How can adding a functional gene eliminate the symptoms of a genetic disease?

   Model answer

   Once the cell holds a working copy it can transcribe and translate it, so the missing protein is made and the blocked step of metabolism proceeds normally.

4. 4

   What is somatic-cell gene therapy?

   Model answer

   Somatic-cell gene therapy inserts the gene into the body cells of the affected tissue, so only that patient is treated.

5. 5

   What is germ-line gene therapy?

   Model answer

   Germ-line gene therapy alters the gene in gametes or in a very early embryo, so the change is present in every cell of the resulting individual and is passed on to their descendants.

6. 6

   Give two advantages of somatic-cell gene therapy.

   Model answer

   It relieves the symptoms of the individual patient without altering the genes of any future generation, and because no inherited change is made it raises far fewer ethical objections.

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