Overview of Metabolism

Catabolism breaks down complex food molecules like polysaccharides, lipids, and proteins into simpler molecules such as sugars, fatty acids, and amino acids, releasing energy as ATP. Anabolism is the reverse process, where small precursors use ATP energy to synthesize complex polymers like glycogen for energy storage and cellular structures.

Cells maintain ATP balance through various regulatory systems including the endocrine system, regulatory enzymes, and positive and negative feedback loops that modulate gene expression patterns. These mechanisms adjust the rates of ATP-producing and ATP-utilizing reactions to keep cellular energy levels stable.

Glucose is metabolized through biochemical pathways to produce pyruvate and ATP via glycolysis. These simpler molecules are then processed inside cells to generate energy in the form of ATP, which powers cellular functions and biosynthetic reactions necessary for cell survival.

Primary metabolites like amino acids and fatty acids are essential chemicals for plant growth and development. Secondary metabolites provide survival advantages, such as terpenes and phenolics for defense against microbes and pests, and flavonoids for flower pigmentation and plant protection.

Enzymopathies are rare genetic disorders where the body lacks specific enzymes needed to break down certain food molecules. People with these conditions cannot efficiently metabolize particular complex molecules to produce energy. For example, fructose intolerance patients lack aldolase-B enzyme, preventing fructose metabolism.

Microbes obtain energy and carbon from both organic and inorganic sources using different metabolic pathways. For example, Bacillus metabolizes organic molecules like starch and cellulose, while Azotobacter and Rhizobium oxidize inorganic molecules such as nitrogen. Cyanobacteria produce glucose through photosynthesis.

Oxygen acts as an oxidizing agent in animal metabolism, enabling the breakdown of complex food molecules to produce ATP energy. This energy is then used for synthesizing necessary macromolecules and maintaining cellular functions required for growth, reproduction, and overall organism survival.