Which statement is true about housekeeping genes in expression studies?

• A. They provide stable references for normalization
• B. They measure high expression to test dynamic range
• C. They serve exclusively as negative controls
• D. They are used to calibrate sequencing machines

Answer: (A)

Housekeeping genes provide stable references for normalization in expression studies. They’re needed because they’re involved in basic cellular functions and tend to be expressed at fairly constant levels across different tissues and conditions. Using them as internal controls helps adjust for differences in the amount of starting material, RNA quality, and technical variation from steps like reverse transcription or sequencing. By comparing the expression of a gene of interest to that stable reference, you obtain normalized, comparable data that reflect real biological changes rather than technical noise. While other choices mention high expression, negative controls, or instrument calibration, those aren’t the primary role of housekeeping genes; they’re about stable normalization references.