It is for this reason that is referred to as a complementary DNA or cDNA. Though there are numerous processes for synthesizing cDNA, the best way of doing so is by using mature or fully spliced mRNA. This is usually done by using the enzyme reverse transcriptase.
Ammonia is used as refrigerant prominently in the refrigeration systems of food industry like dairies, ice creams plants, frozen food production plants, cold storage warehouses, processors of fish, poultry and meat and number of other applications.
Yes there is ammonia in urine but it is also loaded with bacteria. It's not a very good sterilizing agent at all but in a survival situation it is a last resort. This just in: Mandyspl: Your chemistry is way off. Mixing bleach and ammonia makes Chlorine gas.