Nutrition Science and Everyday Application - beta v 0.1

200 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
HOW GLUCOSE PROVIDES ENERGY
Now let’s zoom in on how exactly glucose provides energy to the cell. We can trace this
process in the figure below.
Figure 4.17. Overview of glucose metabolism in the fed state, when there is adequate glucose
available. Glucose can be used to generate ATP for energy, or it can be stored in the form of
glycogen or converted to fat for storage in adipose tissue.
1. Glucose, a 6-carbon molecule, is broken down to two 3-carbon molecules called
pyruvate through a process called glycolysis.
2. Pyruvate enters a mitochondrion of the cell, where it is converted to a molecule
called acetyl CoA.
3. Acetyl CoA goes through a series of reactions called the Krebs cycle. This cycle
requires oxygen and produces carbon dioxide. It also produces several important
high energy electron carriers called NADH 2 and FADH 2 .
4. These high energy electron carriers go through the electron transport chain to