The heaviest element found in any appreciable amount in nature is uranium, atomic number 92. (The atomic number refers to the number of protons in an atom's nucleus.) Beyond that, scientists must create new elements in accelerators, usually by smashing a beam of light atoms into a target of heavy atoms.
Three major types of RNA are mRNA, or messenger RNA, that serve as temporary copies of the information found in DNA; rRNA, or ribosomal RNA, that serve as structural components of protein-making structures known as ribosomes; and finally, tRNA, or transfer RNA, that ferry amino acids to the ribosome to be assembled .
RNA carries genetic information from the nucleus to ribosomes for the synthesis of proteins; while tRNA carries specific amino acids to the ribosomes to assist the protein biosynthesis, and on the other hand, rRNA provides the structural framework for the formation of ribosomes.
