What is DNA?

Picture: DNA.

DNA is a hereditary substance that almost all organisms have. Living organisms have a large number of cells. Each cell has the same DNA. Most DNA can be found in the cell nucleus. They are called nuclear DNA. Small amounts of DNA are located in the mitochondria, which is called mitocondrial DNA or mtDNA.

DNA is identified based on four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The order of the base can identify a certain organism from others. Nearly every cell in the human body has similar DNA.

The DNA will pair with each other, A with T and C with G. These pairs are called base pairs. Then, the pairs are attached to a sugar molecule and a phosphate molecule to form nucleotide. Nucleotides from two long strands that form a spiral called a double helix. It is like a ladder.

DNA is able to replicate or make copies of itself. That's why it is very helpful in identifying an organism, including humans.

("What is DNA," 2015)

Sources: Pathway to English for Senior High School Grade XII General Program (Erlangga).