Seafood -- including clams, trout, salmon, sardines, haddock and oysters -- are a rich source of B12. Clam mollusks contain 84.1 micrograms and oysters contain 13.3 micrograms per 3 ounces. Vitamin B12 is also found in cod, catfish, crab and swordfish. Consume milk, cheese and yogurt to increase your daily B12 intake.eady-to-eat breakfast cereals are an excellent source of B12 and folic acid. Folic acid is also added to rice, egg noodles, bread, pasta, corn meals, orange drinks and tomato juice. Tomato juice provides 10 percent of the daily value per 6 ounces and egg noodles provide 15 percent of folic acid in 1/2 cup.
If it was one DNA letter for one amino acid then you could only code for a maximum of four amino acids. Two letters in every possible combination could code for up to sixteen amino acids. Still, not enough. But three DNA letters provide more than enough combinations to code for all twenty amino acids.
All proteins are composed of amino acids. An amino acid is any one of a class of organic compounds containing a certain amino and carboxyl group. The amino acids are the chief building blocks of proteins; that is, proteins are made by putting various amino acids together into specific combinations.