$NADH$ and $NAD^+$: Life's reducer and oxidant

The $NADH$ can be compared to a basket filled with a hydrogen ion and two electrons. It can transmit these electrons so act as reducer . The $NAD^+$ is comparable to the empty basket. It can recapture both electrons and hydrogen ion (dehydrogenate!), so act as oxidant.

The structure of the $NADH$

1 : adenine 2 : ribose 3 : nicotinamide 4 : diphosphate group Hence the name: NicotinamideAdenineDinucleotide

How the $NADH$ works

The exchange $H^+$ and 2 $e^-$ happens in the pyrimidine nucleus of nicotinamide.