RNA synthesis, carried out by RNA polymerase, has both similarities and differences compared to DNA replication, carried out by DNA polymerase. In both, the synthesis occurs by means of the nucleophilic addition-elimination upon a phosphate group, similar to addition-elimination upon carboxylic acid derivatives, made thermodynamically favorable by phosphate cleavage. In both, the direction of synthesis is 5' to 3'. However, unlike DNA polymerase, RNA polymerase carries out RNA synthesis without a primer and unlike DNA polymerase, RNA polymerase does not detect and excise mismatched nucleotides.

In eukaryotes, transcription factors interact with promoters, binding upstream and assisting in RNA polymerase activity. Eukaryotes also possess enhancer sequences. The binding of a glucocorticoid receptor complex to an enhancer sequence, for example, stimulates transcription of certain genes.

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.