DNA
An introduction to DNA.
Short simple articles which explain the role of DNA, what it is and how it’s structure allows it to provide the blueprint for all life.
Cracking the code
The code
The DNA code is very simple. DNA is a long chain of four different units called bases (which are represented in the picture by letters). The information stored on a DNA strand is encoded by the order of these units. The units are like the letters in a written language.
These units are read in groups or words of three called codons. Each codon corresponds to a particular amino acid.
The translation of the DNA code into amino acid order.
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A long list of codons can be translated to a long list of amino acids. When made this chain of amino acids folds itself up to make a protein. By determining the type and order of amino acids in the chain, DNA controls what shape the chain folds up into and so the overall qualities and use of the protein (what is a protein?).
The DNA code is divided into sections that each code for one protein (protein recipes). These sections are called genes. Each gene begins with a ‘start codon’ and ends with a ‘stop codon’.
Reading the code
If a certain protein is needed the appropriate section of DNA or gene is copied and the copy of the gene then goes to a little protein-making machine called a ribosome. The ribosome reads the copy of the gene and as it reads each codon it adds the particular amino acid that the codons specifies to the protein it is making.
The cell as a protein factory
You could imagine a plant or animal cell as a protein factory. There are lots of ribosomes or protein-making machines in the factory. All the instructions for making proteins are stored in books in a library in the middle of the factory. The library acts like the nucleus in a cell and the books like the DNA. Each chapter in these books codes for a particular protein; these chapters are like individual genes. However, the books never go out of the library, instead the chapter needed is photocopied and this photocopy is sent to one of the protein making machines instead.
