La nuova biologia.blu: Cell Energy and Metabolism

Energy and Cell MetabolismPage 3

Cells obtain and transform energy from the environment, primarily using ATP as a currency for energy exchange. Metabolism consists of anabolic reactions (building complex molecules) and catabolic reactions (breaking them down). Enzymes function as catalysts to facilitate these specific reactions at active sites, while redox reactions involve the transfer of electrons, often mediated by coenzymes like NAD.

Glucose MetabolismPage 8

Glucose metabolism involves glycolysis (breaking down glucose into pyruvate), the Krebs cycle (occurring in the mitochondrial matrix), and oxidative phosphorylation (on the mitochondrial inner membrane). In the absence of oxygen, cells use fermentation (lactic or alcoholic) to regenerate NAD+, whereas aerobic respiration yields up to 38 ATP molecules per glucose.

PhotosynthesisPage 17

Photosynthesis captures solar energy to produce glucose and oxygen from carbon dioxide and water. It consists of the light-dependent phase, which generates ATP and NADPH, and the Calvin cycle, which synthesizes carbohydrates.

Cellular TransportPage 20

The plasma membrane regulates substances through passive transport (diffusion, osmosis, facilitated diffusion) and active transport (requiring energy). Large particles are moved via endocytosis and exocytosis, working in synergy to maintain cellular function.

Evolution and OxygenPage 26

The appearance of photosynthesis, driven by ancestors of modern cyanobacteria, introduced significant quantities of oxygen into Earth's atmosphere. This change fundamentally altered the planet's morphology and the course of evolutionary history.