DNA & RNA Primes
An expression of “directionality” https://en.wikipedia.org/wiki/Directionality_(molecular_biology)
“Directionality, in molecular biology and biochemistry, is the end-to-end chemical orientation of a single strand of nucleic acid. In a single strand of DNA or RNA, the chemical convention of naming carbon atoms in the nucleotide pentose-sugar-ring means that there will be a 5′-end (usually pronounced “five-prime end”), which frequently contains a phosphate group attached to the 5′ carbon of the ribose ring, and a 3′-end (usually pronounced “three-prime end”), which typically is unmodified from the ribose -OH substituent. In a DNA double helix, the strands run in opposite directions to permit base pairing between them, which is essential for replication or transcription of the encoded information”
5’-end
https://en.wikipedia.org/wiki/Directionality_(molecular_biology)#5%E2%80%B2-end
“The 5′-end (pronounced “five prime end”) designates the end of the DNA or RNA strand that has the fifth carbon in the sugar-ring of the deoxyribose or ribose at its terminus”
3’-end
https://en.wikipedia.org/wiki/Directionality_(molecular_biology)#3%E2%80%B2-end
“The 3′-end (three prime end) of a strand is so named due to it terminating at the hydroxyl group of the third carbon in the sugar-ring, and is known as the tail end”
“The 3′-hydroxyl is necessary in the synthesis of new nucleic acid molecules as it is ligated (joined) to the 5′-phosphate of a separate nucleotide, allowing the formation of strands of linked nucleotides”
Important page !!
https://en.wikipedia.org/wiki/Sense_(molecular_biology)
References:
Enger, E. D., Ross, F. C. and Bailey, D. B., 2002. Concepts in Biology. 10th ed. New York: McGraw-Hill.