Hey Michelle. Lysine is very good for bones - vitamin C "activates" lysine which causes calcium particles to chemically bond to the collagen fibers in bones. I've read some information on biphosphonates (like Fosamax) from various doctors and many of them believe that these drugs make bones brittle (although the density is increased) - of course all the information from the pharmaceutical companies have nothing but positive things to say. Biphosphonates work by preventing the bone from losing existing calcium (bone normally "turns over" calcium as part of the formation and maintenance process) - but these doctors also see this as a negative in that existing calcium can't be replaced effectively with new calcium as nature dictates without the "old" calcium being removed from the bones at a molecular level. Some of these doctors recommend taking lysine as an alternative to biphosphonates (biphosphonates remain in the bone for many years) because it allows the natural process of bone regeneration to occur - the collagen fibers in bone provide the "toughness" (keeps them from being brittle), so the lysine and vitamin C are critical to bone formation. Some studies also show that lysine can prevent kidney stones by helping the body use the calcium where it should rather than stay in the urinary tract and become crystallized in the kidneys (vitamin D is also critical for calcium absorption).
Chitin appears to be classified as a "sugar" (it is a polymer of glucosamine chemically). In nature, it does appear that chitin is combined with a protein complex to form the exoskeletons and appendages of arthropods like lobsters and crayfish (or crawfish as we say in the south)
(I have to admit I looked up chitin to find this). The glucosamine supplements available today are made from chitin (chondroiton supplements are made from shark cartilage and tracheas). These supplements are believed to help rebuild cartilage (which is largely collagen fibers).
One of the things I learned from all my researh is that the only known function of DNA is to build proteins (proteins can be structural like collagens and keratin, they can form enzymes (chemical catalysts), they can regulate cell activities (many hormones are proteins - others are steroids) and proteins also form antibodies. Thus, it seems to me that proteins are the most important factor in how the body constructs and maintains itself cell by cell. The base pairs in DNA are much like a very advanced computer program (the sequence of the base pairs determines the "coding" - light years more advanced than anything MicroSoft makes) that instruct the body on how to produce and deposit proteins. I personally think DNA is a true miracle of God.