What are knock-out mice used for in research?

• A. Studying the effects of environmental changes
• B. Investigating gene function by lacking a specific gene
• C. To create new vaccines
• D. To enhance breeding programs

Answer: (B)

Knock-out mice are specifically designed to study gene function by having a targeted gene rendered inactive or "knocked out." This process allows researchers to observe the effects of the absence of that specific gene on the organism’s development, physiology, and behavior. By comparing knock-out mice to normal mice with the functional gene, scientists can gain insights into the role of the gene in various biological processes and disease mechanisms. This approach is particularly valuable for understanding the genetic basis of diseases and can also assist in drug development and therapeutic strategies.

The other options do not pertain directly to the primary use of knock-out mice in research. While environmental changes and breeding programs are important areas of study, they do not utilize the specific genetic alteration that characterize knock-out mice. Similarly, while developing new vaccines is a crucial aspect of biotechnology, it typically involves different methodologies and does not specifically require the use of knock-out mice to investigate gene function.