Rheumatoid Arthritis Symptoms In Women. Disorder that is believed to result from an autoimmune process in which the body's immune system attacks itself. It is a system-wide disease that usually last for many years. In some patients, RA affects such organs as the heart, lungs, and eyes.
The first organic molecules formed about 4 billion years ago. This may have happened when lightning sparked chemical reactions in Earthâs early atmosphere. RNA may have been the first organic molecule to form as well as the basis of early life. Explore More Use the time slider in this resource to answer the questions that follow.
Concept 15 DNA and proteins are key molecules of the cell nucleus. In 1869, Friedrich Miescher isolated nuclein, DNA with associated proteins, from cell nuclei. He was the first to identify DNA as a distinct molecule. Phoebus Levene was an organic chemist in the early 1900's. He is perhaps best known for his incorrect tetranucleotide hypothesis of DNA.