Genetic information for the aminoacids assembly during the protein synthesis is stored in short sequences of three nucleotides named <em>codons </em>in the mRNA. Each of the codons represents one of the 20 amino acids used to build the protein. The total number of possible codons is 64, from which 61 codify amino acids -more than one codon codify for the same amino acid-. One of these amino acids is also the start point of protein synthesis. And the left three codons are stopping translation points.
The codons indicating the initiation or stop points during the translation process are:
The start codon AUG is the most common sequence used by eukaryotic cells and places near the 5´extreme of the molecule. However, other codons might be used as well. Prokaryote cells might use the codons GUG or UUG.
The answer is restriction enzymes. These staggered ends are important in recombination of DNA since they allow DNA strands with complementary sticky ends to be easily joined into one piece by DNA ligase. Other restriction enzymes produce blunt ends. These are harder to join by DNA ligase. An example of a restriction ezyme if EcoRI