The sense portions of a pre-mRNA strand made in transcription are called exons.

Here's a breakdown:

* Pre-mRNA: This is the initial RNA molecule transcribed from DNA. It contains both exons and introns.

* Exons: These are the coding sequences that contain the genetic information for protein synthesis. They are the portions of the pre-mRNA that will be spliced together to form the final mature mRNA.

* Introns: These are non-coding sequences that are removed from the pre-mRNA during splicing. They are often referred to as "intervening sequences."

So, the exons are the "sense" portions because they contain the actual instructions for building a protein. The introns are the "nonsense" portions that are removed before the mRNA can be translated into protein.