The upper left shows a diagram of a cell with the subcellular structures (from BioRender). The upper right shows a diagram of a cross-section of a mitochondria with subcompartments labeled. The bottom describes the cytosolic reactions that use NAD+ and the mitochondrial reactions that use NAD+ to generate ATP.
Read more at
N. R. Gough, Much Ado about NAD+ as the Key to Healthy Aging. BioSerendipity (13 June 2018) https://www.bioserendipity.com/anti-aging-supplements-ii/