What is Junk DNA?

About Junk DNA:

• In genetics, the term junk DNA refers to regions of DNA that are noncoding.
• DNA contains instructions (coding) that are used to create proteins in the cell.
• However, the amount of DNA contained inside each cell is vast, and not all of the genetic sequences present within a DNA molecule actually code for a protein.
• Some of this noncoding DNA is used to produce non-coding RNA components such as transfer RNA, regulatory RNA and ribosomal RNA. 
• However, other DNA regions are not transcribed into proteins, nor are they used to produce RNA molecules and their function is unknown. These are known as junk regions of DNA.
• The proportion of coding versus noncoding DNA varies significantly between species.
  • In the human genome, for example, almost all (98%) of the DNA is noncoding, while in bacteria, only 2% of the genetic material does not code for anything.
• However, over the years, researchers have found evidence to suggest that junk DNA may provide some form of functional activity.
• Some lines of evidence suggest that fragments of what were originally non-functional DNA have undergone the process of exaptation throughout evolution.
  • Exaptation refers to the acquisition of a function through means other than natural selection.