Question

8. (6) There are three common types of point mutations that can affect the coding sequence of proteins. What are these mutations? How do the mutations change the mRNA sequence and consequently the protein?

9. (2) If you were to suggest gene therapy to the family, how you describe what the main goal of this therapy is?

10. (2) Different virus have been used as vectors for gene therapy. Andenoviruses are one example that have been used in humans. What is the advantage of using viruses for gene therapy?

11. (2) What are the two main types of gene therapy? How do they differ from each other?

Answer 1

8. The three main type of point mutations are: Substitution, insertion and deletion. A substitution mutation occurs when one base pair is substituted for another. For example, this would occur when one nucleotide containing cytosine is accidentally substituted for one containing guanine. An insertion mutation occurs when an extra base pair is added to a sequence of bases. A deletion mutation is the opposite; it occurs when a base pair is deleted from a sequence. These mutations change the reading frame of genetic code which results into changes in sequence of mRNA and ultimately to the protein.

9. The goal of gene therapy is to cure or slowdown a genetic disease by repairing the damaged gene responsible for the disease. To achieve this goal, gene therapy requires the technology to insert the missing “normal” gene into the DNA of the patient's cells.

10. viruses transduce a wide cell range, can integrate in host's genome and achieve for a long-period expression, besides avoiding a cellular immune response.

11. There are two different types of gene therapy depending on which types of cells are treated:

• Somatic gene therapy: transfer of a section of DNA to any cell of the body that doesn’t produce sperm or eggs. Effects of gene therapy will not be passed onto the patient’s children.
• Germline gene therapy: transfer of a section of DNA to cells that produce eggs or sperm. Effects of gene therapy will be passed onto the patient’s children and subsequent generations.