The base of each cloud is flat and the top of each cloud has rounded towers. When the top of the cumulus clouds resemble the head of a cauliflower, it is called cumulus congestus or towering cumulus. These clouds grow upward and they can develop into giant cumulonimbus clouds, which are thunderstorm clouds.
Peptide Bond. Covalent bond between the nitrogen of the amino group of one amino acid and the carbon of the carboxyl group of a second amino acid, joining the 2 amino acids together in a peptide or protein.
Purines are one of two families of nitrogen-containing molecules called nitrogenous bases. Pyrimidines are the other family of nitrogenous bases. Nitrogenous bases are needed to construct the genetic material in every living organism. Common substances, like caffeine, are purines, and purines are even used to develop many important medications. They are also an essential part of DNA.