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-area historical tornado activity is slightly below Virginia state average. It is 52% smaller than the overall U.S. average. On 7/12/1964, a category F2 (max. wind speeds 113-157 mph) tornado 5.7 miles away from the Gretna town center caused between $500 and $5000 in damages.