Why Is DNA Important to Living Organisms?

DNA is the genetic blueprint for all life forms on Earth. The sequence in which a DNA strand's components are paired and sequenced determines everything about the organism that it encodes.

History

• DNA, or deoxyribonucleic acid, was discovered in 1869. It was not until 1953 that scientists discovered what DNA looked like. James Watson and Francis Crick received the 1962 Nobel Prize in Medicine for their discovery of DNA's double helix.

Structure

• DNA looks like a twisted ladder. The "uprights" are composed of alternating molecules of sugar and phosphate, while the "rungs" are composed of four chemical bases--adenine, cytosine, guanine and thymine--which combine in specific ways. Each combination of bases, a sugar molecule and a phosphate group makes one nucleotide. The full molecule of DNA consists of millions of nucleotides, attached end-to-end in very long strands.

Significance

• DNA is important because it encodes complete information for all life forms. DNA determines everything about an organism: what it is, what its physical features will be and even what diseases it will be predisposed to.

Fun Fact

• According to Stanford University's online Introduction to Genetics, the human genome holds about 3 billion nucleotides--the equivalent of a 3 gigabyte hard drive's information storage capacity.