In this module:

RNA

RNA, or ribonucleic acid, is a polymer of nucleotides, similar to DNA. RNA and DNA differ in several important ways, however.

Click on the step numbers below to see how DNA and RNA are different. Click on the mouse at left to clear the images and text.

DNA is double stranded, while RNA is single-stranded.

The 2' carbon of DNA binds two hydrogen atoms, while the 2' carbon of RNA binds a hydrogen atom and a hydroxyl group.

DNA has thymine (T), while RNA has uracil (U). As described in the DNA 1 module, both can form base pairs with adenine (A).

Three kinds of RNA are found in cells. Their roles should become clear to you as you go through this module.

• messenger RNA (mRNA): carries genetic information from DNA to the ribosome, the "factory" where protein synthesis takes place. mRNA is the "blueprint" for how a protein should be put together.

• ribosomal RNA (rRNA): the major component of ribosomes. rRNA is quite large, so its exact structure and function are still unknown.

• transfer RNA (tRNA): captures amino acids and transfers them to ribosomes, where they are assembled in the proper order into proteins.