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Facts about DNA for Kids

DNA is a nucleic acid; alongside proteins and carbohydrates, nucleic acids compose the three major macromolecules essential for all known forms of life. The two DNA strands are known as polynucleotides since they are composed of simpler units called nucleotides.

  • The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone.
  • According to base pairing rules (A with T, and C with G), hydrogen bonds bind the nitrogenous bases of the two separate polynucleotide strands to make double-stranded DNA.
  • Under the genetic code, RNA strands are translated to specify the sequence of amino acids within proteins.
  • During cell division these chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes.
  • Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts.
  • DNA was first identified and isolated by Friedrich Miescher in 1869 at the University of Tübingen, a substance he called nuclein, and the double helix structure of DNA was first discovered in 1953 by Watson and Crick at the University of Cambridge, using experimental data collected by Rosalind Franklin and Maurice Wilkins.
  • Although each individual repeating unit is very small, DNA polymers can be very large molecules containing millions of nucleotides.
  • The DNA in the largest human chromosome, chromosome number 1, consists of approximately 220 million base pairs and would be 85 mm long if straightened.
  • In living organisms DNA does not usually exist as a single molecule, but instead as a pair of molecules that are held tightly together.
  • The DNA double helix is stabilized primarily by two forces: hydrogen bonds between nucleotides and base-stacking interactions among aromatic nucleobases.
  • A few DNA sequences in prokaryotes and eukaryotes, and more in plasmids and viruses, blur the distinction between sense and antisense strands by having overlapping genes.
  • This ancient RNA world where nucleic acid would have been used for both catalysis and genetics may have influenced the evolution of the current genetic code based on four nucleotide bases.