1. Anabolism (Building Up)
* Definition: Anabolism is the set of metabolic processes that construct molecules from smaller units. This requires energy input. Think of it like building a house from bricks.
* Examples:
* Protein synthesis: Creating proteins from amino acids.
* Photosynthesis: Plants using sunlight to build sugars.
* Glycogenesis: Making glycogen (stored glucose) from glucose molecules.
* Lipid synthesis: Making fats from fatty acids and glycerol.
2. Catabolism (Breaking Down)
* Definition: Catabolism is the set of metabolic processes that break down molecules into smaller units. This releases energy. Think of it like dismantling a house to retrieve the bricks.
* Examples:
* Cellular respiration: Breaking down glucose to produce energy (ATP).
* Glycogenolysis: Breaking down glycogen to release glucose.
* Lipolysis: Breaking down fats into fatty acids and glycerol.
* Protein breakdown: Breaking down proteins into amino acids.
3. Energy Metabolism
* Definition: This encompasses the processes involved in obtaining, storing, and utilizing energy within cells. It's the foundation of all metabolic activity.
* Key examples:
* Cellular respiration: The primary way cells obtain energy from glucose.
* Photosynthesis: The process plants use to capture energy from sunlight and convert it into chemical energy (sugars).
* ATP production: Cells use the energy released from catabolic processes to create ATP, the primary energy currency of the cell.
4. Biosynthesis
* Definition: Biosynthesis is the synthesis of complex molecules from simpler ones within cells. This is a broader category encompassing many anabolic processes.
* Examples:
* Nucleotide synthesis: Making the building blocks of DNA and RNA.
* Hormone synthesis: Cells create hormones to regulate various bodily functions.
* Enzyme synthesis: Cells make enzymes that catalyze (speed up) specific chemical reactions.
Important Note: Metabolism is a complex and interconnected network. The processes described above are tightly regulated and interdependent.
