What is Cellular Respiration?
Cellular respiration is a set of metabolic processes that take place within a
cell to convert biochemical energy from nutrients into
adenosine triphosphate (ATP), and then release waste products. This process is essential for the survival of cells as it provides the energy required for various cellular functions.
Where Does It Occur?
Cellular respiration primarily occurs in the
mitochondria of
eukaryotic cells. The mitochondria are often referred to as the "powerhouses" of the cell because they generate most of the cell's supply of ATP.
Glycolysis
Glycolysis takes place in the
cytoplasm of the cell and involves the breakdown of one molecule of glucose into two molecules of
pyruvate. This process results in a net gain of two ATP molecules and two
NADH molecules.
The Krebs Cycle
The pyruvate molecules generated from glycolysis are transported into the mitochondria, where they undergo further breakdown in the Krebs cycle. This cycle produces
carbon dioxide,
NADH,
FADH2, and a small amount of ATP.
Electron Transport Chain (ETC)
The NADH and FADH2 produced from the previous stages donate electrons to the electron transport chain, which is located in the inner mitochondrial membrane. The flow of electrons through the ETC creates a
proton gradient that drives the synthesis of ATP through a process known as
oxidative phosphorylation.
What are the Byproducts?
The main byproducts of cellular respiration are carbon dioxide and water. These waste products are expelled from the cell and ultimately from the organism through processes like exhalation and urination.
How Does It Differ from Photosynthesis?
While cellular respiration is a catabolic pathway that breaks down molecules to release energy,
photosynthesis is an anabolic pathway that builds molecules using energy from light. Photosynthesis occurs in the
chloroplasts of plant cells and some algae, converting carbon dioxide and water into glucose and oxygen.
Conclusion
Cellular respiration is a fundamental process that enables cells to harvest energy from nutrients, ensuring their survival and proper function. Understanding its intricacies provides insights into health, disease, and the overall functioning of living organisms.
