In this video, we're going to begin our lesson on the pentose phosphate pathway. The pentose phosphate pathway is commonly abbreviated as PPP and is a glycolysis alternative pathway. It is going to produce carbon dioxide or CO2, as well as the electron carrier NADPH, which, recall from our previous lesson videos, is an electron carrier important for biosynthetic reactions, or reactions that build important cell molecules and cell structures. The pentose phosphate pathway also produces important precursors for biosynthesis, and we'll be able to talk more about those precursors down below once we get to our image.
The pentose phosphate pathway can occur in both prokaryotes and eukaryotes. For example, it occurs in red blood cells. It's important to note that the pentose phosphate pathway does not produce any ATP. Instead, it generates really important precursor metabolites, which are intermediate molecules important for anabolic pathways or pathways that build important cell molecules and cell structures.
Let's take a quick look at our image down below to get a better understanding of this pentose phosphate pathway or this PPP pathway. It is an alternative pathway to glycolysis. The glucose molecule, instead of undergoing the normal glycolysis pathway, in some cases, can be filtered down into the pentose phosphate pathway. This pathway consists of many complex reactions, but ultimately, it creates NADPH and some carbon dioxide.
Additionally, it will generate important precursor metabolites, including ribulose 5-phosphate, which is a crucial precursor for nucleotide biosynthesis. The pentose phosphate pathway produces ribulose 5-phosphate, needed to create the nucleotides shown below. These nucleotides are important for the formation of nucleic acids such as DNA and RNA. The pathway can also produce erythrose 5-phosphate, which is crucial for the biosynthesis of specific types of amino acids, specifically some of the aromatic amino acids such as Tyrosine and Tryptophan.
Finally, the pentose phosphate pathway can also generate glyceraldehyde 3-phosphate, which is recalled as G3P. Glyceraldehyde 3-phosphate is a glycolysis intermediate. This means that the Pentose Phosphate pathway can actually be fed back into the glycolysis pathway. The pentose phosphate pathway connects to the glycolysis pathway, and it's G3P that makes that connection. This G3P, produced by the phosphate pathway, can be filtered back into the energy harvest phase of glycolysis, so that it can continue to make pyruvate, and then that pyruvate can continue down the normal path for cellular respiration.
This concludes our brief lesson on the pentose phosphate pathway and how it is an alternative pathway to glycolysis that is going to create really important precursor metabolites important for biosynthetic pathways, including the production of NADPH, ribulose 5-phosphate, and erythrose 5-phosphate. This concludes this video, and we'll be able to get some practice applying these concepts as we move forward. So, I'll see you all in our next video.
