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.
However, there are incorporated and unincorporated cities in the parishes (counties) tâ¦hat surround Orleans Parish. These include Metairie and the city of Kenner to the west, and the city of Gretna on the West Bank of the Mississippi River, adjacent to the New Orleans district of Algiers.