QUESTION 2 1998

 

 

By using the techniques of genetic engineering, scientists are able to modify genetic material so that a particular gene of interest from one cell can be incorporated into a different cell.

· Describe a procedure by which this can be done.

· Explain the purpose of each step of your procedure.

· Describe how you could determine whether the gene was successfully incorporated.

· Describe an example of how gene transfer and incorporation have been used in a biomedical or commercial application.

 

 

 

A 1pt obtaining gene: B Purpose for 1-3 steps of procedure (Why)

restriction enzymes 1pt e.g. restriction enzymes to produce sticky ends;

mRNA --> cDNA cDNA has no introns which bacteria can’t aa seq--> DNA splice.

isolating plasmid with choice gene

 

1 pt making a packaging/ delivery system 1pt so gene can be delivered to specific site;

make vector (plasmid, virus, YAC ...); so plasmid can be taken up by host cell;

gene gun; ligation to vector. so gene is placed with appropriate regulatory sequences.

 

1 pt incorporating: transformation (CaCl2, heat 1 pt change permeability (competence) of host; shock), viral infection, ligase, (covalently) bond piece into host DNA. electroporation, PEG

1 pt <-----------------------------elaboration ---------------------------->

(appropriate and detailed extra description: controlled experimental design, explanation of electrophoresis or use of radioactive/fluorescent probe)

 

 

C 1 pt how to determine gene incorporation / expression

NOT phenotypic change alone

e.g. antibiotic resistance color change

protein assay change in electrophoretic mobility

reporter genes sequencing

probe

1 pt Elaboration (detailed explanation of how, why it works, etc.; e.g. dideoxynucleotide method of gene sequencing.)

 

 

D 1 pt Application (one)

e.g. transgenic animal FlavrSavr Tomato frost resistance

herbicide resistance monoclonal antibodies growth hormone

gene therapy (specific) insulin production making clotting factor

1 pt Elaboration (not just second example; explanation of importance, how it is done, etc.)