MCAT Organic Chemistry Review

Nitrogen- and Phosphorus-Containing Compounds


Organic chemistry is the study of carbon-containing molecules. But as you’ve seen, carbon is not the only element that plays a role in organic molecules; many of the functional groups we’ve explored up until this point also include hydrogen and oxygen. Together, these three elements make up 93% of the composition of the human body by weight. But other atoms also contribute to biomolecules: nitrogen comprises 3.2% of body weight and phosphorus 1.0%.

In this chapter, we’ll take a look at some biologically important molecules that contain nitrogen and phosphorus. In addition to the amides explored in the previous chapter, amino acids also contain nitrogen. These building blocks of proteins are discussed in depth in Chapter 1 of MCAT Biochemistry Review; in this chapter, we review their structure and focus on laboratory methods for synthesizing amino acids. Finally, we turn our attention to phosphorus-containing molecules, which often are used to transfer energy—or store genetic information.