USA Biology Olympiad (USABO) Practice Exam

What is the purpose of hybridizing a probe for gene X to extracted RNA on a membrane?

1. To quantify the amount of RNA

2. To determine if Gene X is expressed in liver cells

3. To enhance the stability of RNA fragments

4. To modify the RNA structure

The correct answer is: To determine if Gene X is expressed in liver cells

The purpose of hybridizing a probe for gene X to extracted RNA on a membrane is to determine if Gene X is expressed in liver cells. This process, commonly known as Northern blotting, involves transferring RNA samples from a gel onto a membrane and using a labeled probe that is complementary to the sequence of Gene X. If the probe hybridizes with the RNA, it indicates that the gene is being expressed in the cells from which the RNA was extracted. Detecting whether a gene is expressed is fundamental in understanding gene function and regulation within specific tissues. For instance, analyzing the expression of Gene X in liver cells can provide insights into its role in liver physiology, its involvement in metabolic processes, or its implications in liver diseases. Therefore, this technique is invaluable in molecular biology for investigating gene expression patterns across different tissues or conditions.