Difference between photosynthesis and respiration

The photosynthesis It is the biological process where solar energy is used to transform carbon dioxide and water into carbohydrates and oxygen. The cellular respiration It is the biological process by which carbohydrates and oxygen are transformed to produce energy in the form of ATP.

Photosynthesis	Breathing
Definition	Light-driven organic compound formation process.	Process of using organic compounds to obtain chemical energy.
Where is it done?	Chloroplasts (plants and algae) Plasma membrane (cyanobacteria)	Cytoplasm and mitochondria (eukaryotes) Plasma membrane (bacteria, archaea)
Who do it?	Photoautotrophic organisms: Plants Algae Cyanobacteria	Most living organisms: Plants Animals Mushrooms Protozoa Bacteria
What does it produce?	Glucose (C6H12OR6) Oxygen O2	Carbon dioxide (CO2) Water (H2OR) ATP
Phases	Light dependent Independent of Light	Glycolysis Krebs cycle Oxidative phosphorylation
Electron transport chain	Photosystems I and II	Complexes I, II, III and IV
Types	C3 photosynthesis C4 photosynthesis CAM photosynthesis	Aerobic respiration Anaerobic respiration
Importance	Production of carbohydrates. Release of oxygen. Transformation of light energy into chemical energy.	Obtaining energy from carbohydrates. Release of carbon dioxide for the greenhouse effect.
Equation	6CO2 + 6H2O + light → C6H12OR6 + 6O2	C6H12OR6+ 6O2→ 6CO2+ 6H2O + ATP

What is photosynthesis?

Photosynthesis is the process of transforming carbon dioxide and water to form sugars and oxygen. In this process the energy of light is transformed into chemical energy.

The organisms that carry out photosynthesis are photoautotrophs: plants, algae, and cyanobacteria. In plants, photosynthesis takes place in the leaves, where chloroplasts are found. In cyanobacteria, the photosynthetic machinery is found in the plasma membrane.

The general chemical reaction of photosynthesis is summarized in the following equation:

6CO₂ + 6H₂O + light → C₆H₁₂OR₆ + 6O₂

where from carbon dioxide, water and light energy glucose is obtained and oxygen is released into the atmosphere.

Phases of photosynthesis

Photosynthesis reactions are classified into two phases:

• Light dependent phase: Energy derived from sunlight activates an electron in chlorophyll, which enters the electron transport chain of the chloroplast and produces ATP, oxygen, and reducing agents.
• Phase independent of light (or dark phase): carbon fixation reactions are carried out, where ATP and reducing agents produced in the light phase to convert carbon dioxide into sugar.

Types of photosynthesis

Plants can be differentiated by the type of photosynthesis they perform:

• C3 photosynthesis: In most plants carbon dioxide binds the three-carbon phosphoglyceric acid molecule.
• C4 photosynthesis: In corn and sugar cane, carbon dioxide binds to the four-carbon molecule oxaloacetic acid.
• CAM photosynthesis: found in succulent plants.

What is cellular respiration?

The breathing It is the cellular process that allows the energy stored in carbohydrates to be used using oxygen. The products are carbon dioxide, ATP and water. ATP is used for metabolic reactions while CO₂ it leaves the cell and is then eliminated.

Most living organisms carry out cellular respiration:

• in plants, animals, fungi and protozoa it is carried out in the mitochondria and the cytoplasm.
• In some bacteria and archaea it is carried out on the plasma membrane.

The general chemical reaction of respiration is summarized in the following equation:

C₆H₁₂OR₆ + 6O₂ → 6CO₂ + 6H₂OR

where glucose reacts with oxygen resulting in ATP, carbon dioxide, and water.

Phases of cellular respiration

Cellular respiration reactions can be classified into three phases:

• Glycolysis: it is the first route of decomposition of glucose to obtain energy, pyruvate and reducing agents.
• Krebs cycle or citric acid cyclePyruvate enters a cycle of enzymatic reactions to break down into carbon dioxide and produce ATP and reducing agents.
• Oxidative phosphorylation: is the metabolic pathway that captures electrons and reducing agents to produce more ATP.

Types of cellular respiration

Respiration can be of two types depending on the compound that accepts electrons:

• Aerobic respiration: oxygen O₂ is the molecule that accepts electrons to transform into water (H₂OR).
• Anaerobic respiration: in environments where O is not present₂Some microorganisms (bacteria and archaea) use other molecules as electron acceptors, for example sulfate and nitrate.

You may also be interested in seeing Types of respiration.

Relationship between photosynthesis and cellular respiration

Photosynthesis and respiration are complementary processes:

• Photosynthesis uses solar energy to produce organic compounds; respiration uses organic compounds to obtain chemical energy.
• The organic compounds of photosynthesis serve as food for organisms that are not photosynthetic.
• Carbon dioxide is transformed into organic compounds by photosynthesis; organic compounds are transformed into carbon dioxide by respiration.
• In photosynthesis oxygen is released which is then used in respiration.
• Photosynthesis and respiration are part of the carbon life cycle.
• Both processes use chains of electron transporters to capture the energy needed for other reactions.

It may interest you to see Autotrophic and heterotrophic organisms

References

Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., Walter, P. (2008) Molecular Biology of the Cell 5th ed. Garland Science.

Doctor in Biochemistry from the Venezuelan Institute of Scientific Research (IVIC), with a degree in Bioanalysis from the Central University of Venezuela.