Biology 9700 · AS & A Level · Genetic technology applied to medicine
Genetic technology applied to medicine — practice question
If blood supply to the brain is cut down severely, brain cells die; this event is known as a stroke. The outcomes after a stroke can vary from recovery to lasting brain damage and death.
A newly developed emergency gene therapy for people who may develop brain damage after a stroke was tested in mice.
• The human granulocyte colony-stimulating factor, hG-CSF, is a protein that encourages stem cell production in bone marrow.
• mRNA coding for hG-CSF was isolated and then used to produce cDNA.
• This cDNA was inserted into an adeno-associated virus (AAV) vector and delivered in eye drops to mice immediately after they had a stroke.
(a(i))[2]
Explain the meaning of gene therapy.
(a(ii))[2]
Describe the roles of reverse transcriptase and DNA polymerase when making cDNA for hG-CSF.
(a(iii))[2]
The AAV vector used was unable to copy itself inside the target cells. Suggest why the researchers selected a vector that could not replicate.
(b(i))[3]
Explain why the mice in group D were included in the study.
(b(ii))[1]
Explain why the mice in group D were included in the study.
(c)[4]
Use the results in Table 5.1 to evaluate the benefits of gene therapy treatment, with AAV vector carrying the gene for hG-CSF, for people who have a stroke.
Worked solution & mark scheme
This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A disease arising from a faulty recessive allele” …