Final answer:
Introns are the non-coding portions of DNA that need to be separated from the coding regions during transcription. They are removed through a process called splicing, and the remaining coding regions are called exons.
Step-by-step explanation:
The non-coding portions of DNA that are separated from the portions of DNA actually used during transcription are called introns.
In eukaryotic genes, introns are regions of DNA that do not code for proteins and need to be removed before translation.
This process, known as splicing, involves the joining of the remaining coding regions called exons. Introns are removed by a complex structure called a spliceosome.