This process begins in the where glucose is broken down into smaller molecules to produce energy. the second part of the process takes place in the

This process begins in the Cytoplasm first, and the second part takes place in the Mitochondria.

Explanation:

What is this process you may ask?

First, this process is Cellular Respiration, the oxidation of glucose to release energy.

It occurs in mitochondria of all living cells. The energy that is released, bit by bit, is stored in Adenosine Triphosphate(ATP) molecules.

One molecule of 6-carbon glucose has to be broken down into two molecules of the 3-carbon pyruvic acid by enzymes in the cytoplasm of the cell. These reactions do not require oxygen. Each molecule of pyruvic acid is oxidized completely to carbon dioxide and water in the Mitochondrion.

And the story continues... in Kreb's Cycle.

PeAcE.