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DNA |
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DNA was first isolated by Friedrich Miescher who discovered a substance he called "nuclein" in 1869. In 1929 this discovery was followed by Phoebus Levene's identification of the base, sugar and phosphate nucleotide unit |
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| Using X-ray diffraction data from Rosalind Franklin and the information that the bases were paired, James D. Watson and Francis Crick produced the first accurate model of DNA structure in 1953 in their article The Molecular structure of Nucleic Acids.Watson and Crick described how proteins are produced from nucleic DNA. For their outstanding contribution Watson, Crick, and Maurice Wilkins jointly received the Nobel Prize in the year 1962. |
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| Once the genetic “book of life” had been discovered, researchers needed new tools to decipher its contents. In the 1970s, scientists wrestled with methods to work with particular stretches of DNA (genes) |
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| The detailed structure of DNA |
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| The DNA in your genes tells the cell what amino acids (protein building blocks) to put together to make a protein. The letters that make up the words are called DNA bases, and there are only four of them: Adenine (A), Guanine (G), Cytosine(C), and Thymine (T). It's hard to believe that an alphabet with only four letters can make something as wonderful and complex as a person! |
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| DNA stores the instructions for making you, but before your cells can use DNA it has to be "transcribed" into something they can use. To do this, the DNA strands pull apart and RNA, which is a single strand, comes in and matches up with the bases on one of the strands. |
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| The smallest piece of RNA that means something to the cell is a group of 3 base pairs that is called a codon. Codons tell a cell what amino acid to build. Amino acids are the building blocks of proteins, and proteins are what make the body grow and break down food and carry oxygen to cells - all the things that our bodies need to do to stay alive are based on proteins doing their jobs. |
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| We have a huge amount of DNA in each of our cells. If the DNA from just one of your cells was typed in books, a list of the 3 billion base pairs would fill 200 telephone books. That is from just one cell - and we have trillions of cells in our bodies, and most cells have a complete set of DNA! |
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| Each type of base on one strand forms a bond with just one type of base on the other strand. This is called complementary base pairing. Here, purines form hydrogen bonds to pyrimidines, with A bonding only to T, and C bonding only to G. This arrangement of two nucleotides joined together across the double helix is called a base pair |
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| All the functions of DNA depend on interactions with proteins. These protein interactions can either be non-specific, or the protein can only bind to a particular DNA sequence. Enzymes can also bind to DNA and of these, the polymerases that copy the DNA base sequence in transcription and DNA replication are particularly important. |
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