Nucleic acids are polymers of nucleotides in which the 5' oxygen of one nucleotide is linked to the 3' oxygen of another by means of a phosphate ester linkage, called a phosphodiester bond. DNA differs from RNA in that DNA lacks a hydroxyl group on the number two carbon of ribose.

The Watson and Crick model of DNA structure proposed the double helix in which adenine and thymine form a base pair connected by two hydrogen bonds while guanine and cytosine form a base pair with three hydrogen bonds. Base pairing allows DNA to serve as the template for its own replication as well as to serve as the template for protein biosynthesis. Base pairing allows for the complementary relationship of gene sequence with protein sequence (a triplet of adjacent nucleotides being a codon, standing for a single amino acid) mediated by mRNA and tRNA (although the relationship between the sequence of codons in DNA and the ultimate amino acid sequence in proteins can be complex, especially in eukaryotes, where the primary RNA transcript generally undergoes processing prior to translation on the ribosomes).












The WikiPremed MCAT Course is a comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum. Please read our policies on Privacy and Shipping & Returns.  Contact Us. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course. WikiPremed offers the customers of our publications or our teaching services no guarantees regarding eventual performance on the MCAT.


Creative Commons License
WikiPremed is a trademark of Wisebridge Learning Systems LLC. The work of WikiPremed is published under a Creative Commons Attribution NonCommercial ShareAlike License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions.