Is consuming sugar with food as beneficial as consuming glucose (~half of the amount of sugar)? A few years back I heard at biology class that sugar's molecule consists of half the number of elements of a glucose molecule. So not counting the energy needed to transform two sugar molecules in one glucose molecule, isn't it almost the same (eating N amount of sugar) as eating N/2 of glucose?

You have it backwards. One sugar molecule is equivalent to **two** glucose molecules, though the actual structure of sugar ( _Sucrose_ ) is a _Glucose_ \+ _Fructose_ combination.

While Glucose is metabolized via Glycolysis into two molecules of Pyruvate (which are then used in the Citric Acid Cycle), Fructose enters the Glycolysis metabolism at a later stage as shown here:

!Fructose metabolic pathway.

The GA-3-P is then turned into 2-Phosphoglycerate and then into 2x Pyruvate.

The end result is that a single Sucrose molecule (Glucose + Fructose) [aka - Sugar] is equivalent to 4x Pyruvate, whereas Glucose alone is equivalent to 2x Pyruvate. Or, if you prefer, a single Glucose molecule results in about 32-36 ATP produced, whereas Sucrose will result in 64-72 ATP produced - with ATP being the primary energy carrier of the cell.