BIO101: Introduction to Molecular and Cellular Biology

As their names indicate, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are both nucleic acids. Any nucleic acid is a polymer made up of monomers called nucleotides.

Any nucleotide consists of three components:

1. A pentose (five-carbon sugar)
2. A nitrogenous base attached to the pentose
3. A phosphate group also attached to the pentose

For DNA, the specific pentose in each of its nucleotides is deoxyribose, whereas RNA features ribose as the pentose in each of its nucleotides. There are normally four kinds of DNA nucleotides because there are four normal nitrogenous bases used in DNA: adenine, guanine, cytosine, and thymine.

RNA also features four kinds of nucleotides, and the nitrogenous bases are nearly the same as for DNA, except that RNA uses uracil instead of thymine. DNA functions for self-replication (before a cell divides into two cells) and for transcription, a process that produces RNA. There are different functional categories of RNA including mRNA, tRNA, rRNA, and others.

Watch this overview of DNA and RNA that explains how these important nucleic acids form the blueprint for life's structures. After you watch, you should be able to explain the difference between RNA and DNA, identify the three types of RNA, and discuss the central dogma of how information flows from gene to protein.