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DNA Structure


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dna structure - double helix rendering In 1962, scientists Francis Crick and James Watson were awarded the Nobel prize for their roles in discovering the structure of DNA, which is an acronym for deoxyribonucleic acid.  Anything that is alive, from bacteria to elephants, has DNA.  DNA stores genetic material and passes it on to the next generation.  A copy of a living entity's DNA is passed to developing offspring.  Once the DNA is passed to the developing offspring, it is used to make that offspring's body parts.

DNA's structure allows a molecule to copy itself and allows genetic messages to arrive without getting garbled on the journey.

DNA is a huge molecule called a macromolecule.  However, DNA fits into small cells because it is packed in a process called supercoiling, in which DNA is wrapped around proteins called nucleosomes.  Proteins called histones hold the coils together.

Strands of DNA are divided into chromosomes, a full set of which is stored in the nucleus of each cell.  These chromosomes, which basically instruct how the entire body is built, are called genes.  A gene determines how a specific trait will be expressed.

Chemically, DNA is made of three components:  nitrogen-rich bases, deoxyribose sugars, and phosphates.  When combined, these components form a nucleotide.  Nucleotides come together in pairs to form a single molecule of DNA.

There are four nitrogen-rich bases.  These are adenine, guanine, thymine, and cytosine.  Adenine and guanine have purine bases, which means they are a compound of two rings.  Thymine and cytosine have pyrimidine bases, which means they have a single six-sided ring structure.  These rings stack up in DNA to make the molecule compact and strong.

In order to make a complete nucleotide, the bases are attached to deoxyribose and a phosphate molecule.  Nucleotides are the building blocks of DNA.  To make a complete DNA molecule, these nucleotides join together to make matched pairs and form long double strands called double helixes.

DNA-Structure.com features information about the structure of DNA and the history of DNA testing, as well as DNA testing services and solutions.


  • Robinson, T. R. (2005).  Genetics For Dummies.  Indianapolis:  Wiley Publishing.
  • Schneider, V. (2008).  Francis Crick and James D. Watson.  In M. MacArdle (Ed.), Scientists:  Extraordinary People Who Altered the Course of History.  New York:  Metro Books.

DNA Information Resources

  • DNA Learning Center
    The Dolan DNA Learning Center at Cold Spring Harbor Laboratory is an excellent starting point for information about DNA and human genetics.
  • Genetics Home Reference
    Consumer-friendly information about the effects of genetic variation on human health.

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