4. Among the following which correctly represents “gain of function”-
   (1) Binding of RNA polymerase to promoter
   (2) Over-expression of any gene
   (3) Presence of basal transcription sequences
   (4) Expression at unpredictable time and unpredictable space

Final Answer

“Gain of function” in genetics and molecular biology refers to a gene alteration that leads to increased or new activity of the encoded protein. Among the options provided, the correct representation of gain of function is:

(2) Over-expression of any gene

This means the gene is expressed at higher-than-normal levels, resulting in enhanced function or new capabilities. Over-expression is a classical example of gain of function, seen in many biological processes and diseases like cancer, where genes may be abnormally active to cause growth advantages for cells. Other options either describe normal processes (binding of RNA polymerase, basal transcription sequences) or outcomes of gain of function (expression at unpredictable time and space) but do not directly define gain of function itself.

This classification helps in understanding genetic mutations and their impact on cellular behavior, making it crucial for research in genetics, oncology, and molecular medicine.