Functions of non-coding DNA
Non-coding DNA is often considered 'junk', meaning it has no known function. It is a common misconception that all of the DNA within the cell codes for proteins.
In fact, non-coding DNA is essential for both prokaryotes and eukaryotes. The sections of DNA that code for polypeptides are called genes. Genes account for only a small percentage of eukaryotic DNA.
Introns are regulatory regions in eukaryotes that do not code for proteins. They control transcription and are removed after transcription.
Introns are rare in prokaryotes. Prokaryotic genes tend to be organised into groups known as operons. Operons code for proteins that serve similar functions.
Telomeres have a structural function. They are non-coding regions of DNA that help to prevent the chromosome from being damaged.
Some non-coding DNA sections indicate where a gene starts and ends. Other sections contain sequences that allow enzymes to bind to the DNA.