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.
Gretna is located in southeast Louisiana. Gretna is part of Jefferson County. Gretna has 4.04 square miles of land area and 0.47 square miles of water area. As of 2010-2014, the total Gretna population is 17,801, which has grown 2.17% since 2000. The population growth rate is lower than the state average rate of 2.96% and is much lower than the national average rate of 11.61%. Gretna median household income is $34,158 in 2010-2014 and has grown by 21.71% since 2000.