Photosynthesis
Photosynthesis can be summarized by the following equation:
6CO2 + 6H2O
C6H12O6
+
6O2
Light energy is captured in the chloroplast of plant cells and used to
synthesize glucose molecules. In the process, oxygen is released as a waste
product.
The glucose and oxygen are then used in the mitochondrion of the plant and
animal cell, and the energy is released and used to fuel the synthesis of ATP.
In the reaction, carbon dioxide and water are released in the mitochondrion to
be reused in photosynthesis in the chloroplast.
CELLULAR RESPIRATION
Organisms, such as plants, can trap the energy in sunlight through
photosynthesis and store it in the chemical bonds of carbohydrate molecules.
The principal carbohydrate formed through photosynthesis is glucose. Other
types of organisms, such as animals, fungi, protozoa, and a large portion of the
bacteria, are unable to perform this process. Therefore, these organisms must
rely on the carbohydrates formed in plants to obtain the energy necessary for
their metabolic processes.
Animals and other organisms obtain the energy available in carbohydrates
through the process of cellular respiration. Cells take the carbohydrates into
their cytoplasm, and through a complex series of metabolic processes, they
break down the carbohydrates and release the energy. The energy is generally
not needed immediately; rather it is used to combine adenosine
diphosphate (ADP) with phosphate ions to form adenosine triphosphate
(ATP) molecules. Remember that ATP is the energy currency of the cell.
During the process of cellular respiration, carbon dioxide is given off. This
carbon dioxide can be used by plant cells during photosynthesis to form new
carbohydrates. Also in the process of cellular respiration, oxygen gas is
required to serve as an acceptor of electrons. This oxygen is identical to the
oxygen gas given off during photosynthesis.
Cellular respiration can be summarized as follows:
C6H12O6
+
6O2
6CO2 + 6H2O
From the diagram you can see that there is an interrelationship between the
processes of photosynthesis and cellular respiration, namely the trapping of
energy from the sun and providing energy for cellular processes in the form of
ATP. Below is a diagram showing the structure of a mitochondrion, the site of
cellular respiration.