Final answer:
The mitochondria are the cell's organelles responsible for producing ATP, the cell's main energy currency, especially when glucose and oxygen are present.
Step-by-step explanation:
The mitochondria are bean-shaped, double-membrane-wrapped organelles that produce most of the cell's energy in the form of ATP (adenosine triphosphate) when both glucose and oxygen are available to the cell. Mitochondria, often referred to as the powerhouses or energy factories of a cell, have two separate lipid bilayer membranes. The inner membrane is folded into structures called cristae, which increase the surface area and house key molecules for ATP production. Additionally, mitochondria contain their own ribosomes and DNA, which are essential for their functions.