What is dark DNA?

“Dark DNA” is a term that is sometimes used to describe DNA sequences that do not encode proteins, but may have other functions in the cell. These sequences, which make up a large portion of the genome, are often referred to as “non-coding DNA.” Non-coding DNA includes sequences that regulate the expression of genes, as well as sequences that have structural or other unknown functions. Non-coding DNA was once thought to be “junk” because it did not appear to have any obvious function, but it is now known to play important roles in many biological processes. Some researchers have referred to non-coding DNA as “dark DNA” because much is still unknown about its function, and it has been difficult to study due to its complex and variable nature.