Questions on Genetics

1.Answer the following question in no more than 2-3 well-written sentences:

A DNA coding sequence of ATGCGTGGA(sequence for the rest of the gene)AATTAA encodes a protein chain of 200 amino acids of MET-ARG-GLY-(196 more amino acids)-ASN after splicing. A mutation occurs in which the third G is changed to a T. Using the genetic code below, determine which type of mutation this is and briefly explain how translation will be affected for this protein chain.

2.Answer the following question in no more than 2-3 well-written sentences:

How can the inactivation of one X chromosome in every XX female cell during early embryogenesis lead to females with mild forms of X-linked recessive genetic disorders? 

3.Answer the following question in no more than 2-3 well-written sentences:

You are researching a method of treating beta thalassemia with a corrected hemoglobin gene that is transferred to the host cell by a virus. Would you choose a replication-competent virus or replication-incompetent virus as your vehicle, and why?

4.Answer the following question in no more than 2-3 well-written sentences:

While most gene therapy protocols use viral methods for transferring genes into cells, there are some benefits to non-viral methods that make them the best choice for certain treatments. Briefly (in no more than 2 well-written sentences) mention TWO reasons that a non-viral method might be chosen over a viral mechanism.

5.Answer the following question in no more than 2-3 well-written sentences:

The first gene therapy trials to treat ADA-SCID used peripheral T cells but current gene therapy strategies modify CD34+ hematopoietic progenitor cells. Briefly explain why more recent studies use different cells than the original trials.

6.you need to clone a therapeutic gene into a vector for gene transfer. Below, you can see the area of interest: the therapeutic gene (big blue rectangle) and the DNA on either side of it (thin lines sticking out next to the therapeutic genes. The restriction sites are indicated below: restriction enzyme H cuts at all sites labeled H, restriction enzyme M cuts at all sites labeled M, and restriction enzyme Q cuts at all sites labeled Q. The vector you’ve chosen has restriction sites for all of these enzymes available. Based on this information, which restriction enzyme is the best to choose, and why?

1. The disease that you’re treating has its primary effects on the heart and liver. What type of vector would you choose to deliver this therapeutic gene to its target cells, and why? What other information do you think you would need to make the best decision?
2. The size of the therapeutic gene is 11,783 bp long; it contains 12 exons encoding an mRNA 3,491 bp long. Does this information impact your choice of how to develop your therapeutic gene delivery system? Why or why not?  

7.

1. ZAP70 severe combined immunodeficiency (SCID) is a different type of SCID than we    studied! Do some research and tell me the following information:
   1. Full name of the affected gene
   2. Normal function of this gene (generally—you don’t need a full molecular explanation)
   3. Inheritance pattern
   4. Two types of cells in which this gene is normally expressed
2. Given what you know about SCID from the module, would you want to deliver ZAP70 genes to peripheral T-cells or hematopoietic progenitor cells? Be sure to include pros and cons for both types of cells in your answer.
3. Would you recommend in vivoor ex vivo gene delivery of a ZAP70 gene to these cells, and why?

8.

1. Stargardt disease is an inherited disorder that causes blindness, but we didn’t study it! 95% of all cases of Stargardt disease are caused by mutations in one gene. Do some research and tell me the following information:
   1. Full name of the most commonly affected gene
   2. Normal function of this gene (generally—you don’t need a full molecular explanation)
   3. Inheritance pattern
   4. Type of cell in which this gene is normally expressed
2. What type of vector would you use to deliver a corrected version of this gene, and why? Show your understanding of how this vector would be the best choice based on what you learned in the module.
3. Given what you know about inherited blindness from the module, would you want to deliver the gene you identified above via subretinal injection or intravitreal injection? Be sure to include pros and cons for both types of injection in your answer.