Cellular metabolism refers to the set of chemical reactions that occur within a cell to maintain life. These reactions are organized into metabolic pathways that convert nutrients and energy sources into usable forms of energy and building blocks for cellular processes.
There are two main types of metabolic pathways: catabolic and anabolic. Catabolic pathways break down larger molecules into smaller ones, releasing energy in the process. Anabolic pathways build larger molecules from smaller ones, requiring energy input.
The key reactions involved in cellular metabolism include:
- Glycolysis: Glycolysis is the breakdown of glucose into two molecules of pyruvate, with the net production of two ATP molecules and two NADH molecules. This process occurs in the cytoplasm and is the first step in both aerobic and anaerobic respiration.
- Krebs cycle: The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria. It involves the breakdown of acetyl-CoA, produced from the breakdown of pyruvate, into carbon dioxide and the production of ATP, NADH, and FADH2.
- Electron transport chain: The electron transport chain is a series of proteins and cofactors located in the inner membrane of the mitochondria. It uses the energy from the NADH and FADH2 produced in glycolysis and the Krebs cycle to produce a large amount of ATP through oxidative phosphorylation.
- Photosynthesis: Photosynthesis is the process by which plants and some bacteria convert sunlight into chemical energy in the form of glucose. This process involves the absorption of light energy by chlorophyll, which is used to produce ATP and NADPH. These molecules are then used in the Calvin cycle to produce glucose.
Overall, cellular metabolism is a complex and tightly regulated process that allows cells to obtain energy and build new molecules necessary for life. Disruptions in metabolism can lead to a variety of diseases, including diabetes and cancer.