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.

Q1: What is DNA?

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Source: New class of cancer mutations discovered in so-called 'junk' DNA