**Adenosine triphosphate** or **ATP** is a chemical molecule that serves as energy for different biochemical reactions and processes in the cell. It has three phosphate groups, hence “triphosphate”.

Adenosine triphosphate (ATP) is a chemical compound which serves as the chemical fuel of living organisms. ATP is composed of adenine, ribose, and 3 phosphate groups. In plant cells, this compound is produced in mitochondria and chloroplasts. It is the energy source of a plant cell in doing its metabolic activities and photosynthesis.

ATP, which is produced by the chloroplasts in the first stage of photosynthesis, is used by the cells during dark reactions in the second stage of photosynthesis. In this stage, ATP provides energy when the cells construct organic compounds using carbon dioxide and water during light-independent reactions. Eventually, these organic compounds become glucose, which is a product of the photosynthesis.

**Heterotrophs** are organisms that cannot manufacture their own food, hence their energy source comes from the nutrition they intake.

**Autotrophs** are organisms that can manufacture their own food, via materials and substances from inorganic sources such as light. It can supply energy and nutrients to itself without any help from other organisms.

ATP and glucose are both good sources of energy that can be used by cells to fuel their everyday activities. However, ATP and glucose have their own differences with respect to energy.

Glucose molecules can store a lot of energy. However, this energy cannot be used directly. Glucose must be metabolized in order to release its stored energy that can be used by cells.

On the other hand, ATP is a readily-available form of energy that can be directly used by cells. ATP molecules do not usually function as a form of energy storage, unlike glucose molecules.