The sympathetic nervous systemâs fight-or-flight response is your built-in mechanism for safely escaping a life-threatening emergency, such as a lion lurking behind a bush.
The basic building block of DNA is called a NUCLEOTIDE. A nucleotide is made up of one sugar molecule, one phosphate molecule and one of the four bases. Here is the structural formula for the four nucleotides of DNA. Note that the purine bases (adenine and guanine) have a double ring structure while the pyrimidine bases (thymine and cytosine) have only a single ring.
1 One nitrogenous base. 2  The sugar is deoxyribose in DNA and ribose in RNA. 3  The only difference between the sugars is that ribose has a hydroxyl group (OH) on the 2' carbon and deoxyribose does not. 4  This makes deoxyribose more stable than ribose.5  The phosphate is linked to the 5' carbon of the sugar in both RNA and DNA. nucleotide is formed when a phosphate attahes to the 5' carbon of the sugar and one of the nitrogenous baseses attaches to the 1' carbon of the sugar. A strand of DNA or RNA consists of nucleotides linked together by phosphodiester bonds.