1 the set of exogenic (physical, chemical and biological) processes that alter the physical and chemical state of rocks at or near the earth's surface.  intensity of most weathering decreases with depth, because variations in temperature and moistures decrease with depth.
A gene is a segment of nucleic acid that contains the information necessary to produce a functional product, usually a protein. Genes consist of a long strand of DNA (RNA in some viruses) that contains a promoter, which controls the activity of a gene, and a coding sequence, which determines what the gene produces.
RNAâin this roleâis the âDNA photocopyâ of the cell. When the cell needs to produce a certain protein, it activates the proteinâs gene âthe portion of DNA that codes for that proteinâand produces multiple copies of that piece of DNA in the form of messenger RNA, or mRNA. central tenet of molecular biology states that the flow of genetic information in a cell is from DNA through RNA to proteins: âDNA makes RNA makes proteinâ. Proteins are the workhorses of the cell; they play leading roles in the cell as enzymes, as structural components, and in cell signaling, to name just a few.