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.
When nucleotides connect to form DNA or RNA, the phosphate of one nucleotide attaches via a phosphodiester bond to the 3-carbon of the sugar of the next nucleotide, forming the sugar-phosphate backbone of the nucleic acid.By Anne Marie Helmenstine, Ph.D.hen nucleotides connect to form DNA or RNA, the phosphate of one nucleotide attaches via a phosphodiester bond to the 3-carbon of the sugar of the next nucleotide, forming the sugar-phosphate backbone of the nucleic acid. By Anne Marie Helmenstine, Ph.D.