the nature of DNA

• Triplet code - The code in the base sequences
• codon - A sequence of three bases which codes for an amino acid.
• gene - A section of DNA that contains the complete sequence of codons to code for a protein.
• genetic code - The sequences of bases in DNA are the instructions for the sequences of amino acids in the production of proteins.
• The Genetic code is universal - all organisms use the same code but the sequence of bases coding for each protein will be different
• The DNA nucleotide base code found within a gene is a triplet code. Each sequence of triplet codes for one amino acid

  These triplets of bases are known as codons. Each codon codes for a different amino acid (there are 20 different amino acids that can make up proteins)

  • CAG codes for valine
  • TTC codes for lysine
  • GAC codes for leucine
  • CCG codes for glycine
• Some of these codons code for start (methionine) and stop signals. These signals tell the cell where individual genes start and stop

  This ensures the cell reads the DNA correctly, that the code is non-overlapping and can produce the correct sequences of amino acids 

  
• The non-template strand is referred to as the coding strand because its sequence will be the same as that of the new RNA molecule.

  
• There are four bases so there are 64 different triplets possible (43), yet there are only 20 amino acids that commonly occur in biological proteins. Therefore there are multiple codons coding for the same amino acids

  Due to this the genetic code is referred to as degenerate.