DNA and RNA Bases. In DNA, there are four different bases: adenine (A) and guanine (G) are the larger purines. Cytosine (C) and thymine (T) are the smaller pyrimidines.
Gretna is the second-largest city and parish seat of Jefferson Parish, Louisiana, United States. Gretna is on the west bank of the Mississippi River, just east and across the river from uptown New Orleans. It is part of the New Orleans â Metairie â Kenner Metropolitan Statistical Area. The population was 17,736 at the 2010 census.
Natrona is an unincorporated community in Harrison Township, Allegheny County in the U.S. state of Pennsylvania.he original village of Natrona â then known as East Tarentum â was built as a company town by the Pennsylvania Salt Manufacturing Company in the 1850s.