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.
RNA (ribonucleic acid) molecules differ from DNA molecules in several ways. RNA molecules are single-stranded, and their nucleotides contain ribose rather than deoxyribose sugar. Like DNA, RNA nucleotides each contain one of four organic bases, but whereas adenine, cytosine, and guanine nucleotides occur in both DNA and RNA, thymine nucleotides are found only in DNA. In place of thymine nucleotides, RNA molecules contain uracil nucleotides. The first step in the delivery of information from the nucleus to the cytoplasm is the synthesis of a type of RNA called messenger RNA (mRNA). In messenger RNA synthesis, RNA nucleotides form complementary base pairs with a section of a strand of DNA that encodes a particular protein.