Differentiate a gene knockout from a knock-in allele and give a use case for each.

Differentiate a gene knockout from a knock-in allele and give a use case for each.

• A. Knockout disrupts gene function; knock-in inserts a new sequence at a locus (e.g., reporter).
• B. Knockout inserts a catalytic tag; knock-in disrupts gene function.
• C. Knockout duplicates the entire gene; knock-in deletes regulatory regions.
• D. Knockout and knock-in are the same concept, used interchangeably.

Answer: (A)

The main idea is how the edits affect the gene's function. A knockout removes or disrupts the gene so it can no longer produce a functional protein, revealing what happens when that gene is absent. A knock-in adds a new DNA sequence into a precise genomic location, often keeping the original gene intact while introducing something extra—like a reporter gene (e.g., GFP) or a tagged version of a protein—to study when and where the gene is active or to alter its function in a controlled way. Use cases illustrate the difference: knocking out a gene shows its essential role by producing a loss-of-function phenotype, while knocking in a reporter allows you to monitor expression patterns or track the protein, or to introduce a specific modification. The other statements don’t fit because they misrepresent the edits: a knockout is not about adding a catalytic tag, a knock-in is not primarily about deleting regulatory regions, and the two are not interchangeable concepts.

The main idea is how the edits affect the gene's function. A knockout removes or disrupts the gene so it can no longer produce a functional protein, revealing what happens when that gene is absent. A knock-in adds a new DNA sequence into a precise genomic location, often keeping the original gene intact while introducing something extra—like a reporter gene (e.g., GFP) or a tagged version of a protein—to study when and where the gene is active or to alter its function in a controlled way.

Use cases illustrate the difference: knocking out a gene shows its essential role by producing a loss-of-function phenotype, while knocking in a reporter allows you to monitor expression patterns or track the protein, or to introduce a specific modification.

The other statements don’t fit because they misrepresent the edits: a knockout is not about adding a catalytic tag, a knock-in is not primarily about deleting regulatory regions, and the two are not interchangeable concepts.