Question

What is the advantage of using the neo gene to disrupt the function of a gene in knockout mice?

• A. The neo gene produces an antibiotic that kills unwanted cells
• B. The neo gene is the right size for disabling other genes
• C. The neo gene provides a selectable marker
• D. The neo gene produces a repressor that inhibits transcription of the target gene

Hint:

Neo gene = Neomycin resistance = Selection of successful recombinants.

Answer 1

The Correct Option is C

Step 1: Concept
Gene targeting in embryonic stem (ES) cells is an inefficient process; only a small fraction of cells successfully incorporate the desired DNA.

Step 2: Meaning
A selectable marker is a gene that allows researchers to specifically identify and grow only the cells that have taken up the foreign DNA.

Step 3: Analysis
The $neo$ gene (neomycin phosphotransferase) confers resistance to the antibiotic G418. By including $neo$ within the DNA construct used to disrupt the target gene, researchers can treat the cell culture with G418; only the cells that have successfully integrated the $neo$ gene (and thus disrupted the target gene) will survive.

Step 4: Conclusion
The $neo$ gene acts as a tool for positive selection in the creation of knockout models. Final Answer: (C)