Metabolism - Introduction
Definition
Metabolism is a set of life - sustaining chemical reactions that occur within living organisms. It is the sum total of all the chemical reactions that occur within the organism.
Functions
Each cellular sub-unit has specific, purposeful functions to perform in establishing and maintaining the life of the cell. However, all the cells have in common two major general functions : energy generation and energy utilisation. Metabolism is the process of turning food into energy. Metabolism is also known for the excretion of metabolic wastes.
Metabolic Pathways
The chemical reaction of metabolism are organised into metabolic pathways. There are hundreds of metabolic pathways. The 4 major metabolic pathways are of : Proteins, Carbohydrates, Fats, and Nucleic Acids - later.
Enzymes in Metabolism
Each reaction is facilitated, or catalyse by a protein known as enzymes. Enzymes are the catalysts in the biochemical reactions. This is because it allows for control, efficiency, and the precise management of energy and molecules. Enzymes are crucial to metabolism because they allow organisms to drive desirable reactions that requires energy and will not occur by themselves, by coupling them to spontaneous reactions that release energy.
Anabolism and Catabolism
These chemical reactions fall into 2 basic categories - Anabolism and Catabolism. Anabolism is the process in which large polymers are synthesised. Whereas Catabolism is the process in which the polymers are broken down to release energy.
The Dynamic state of Metabolisms
The balance of input and output processes is here referred to as the dynamic state of metabolisms. Assimilation and breakdown of nutrients are in a constant dynamic flux, so that in an adult, there is a delicately regulated balance between anabolic (biosynthetic) and catabolic (degradative) processes. In a adult, anabolism is equal to catabolism. In a kid, anabolism is greater than catabolism. In a old person, catabolism is greater than anabolism.
Fun facts
The amino acids, hexoses, and the fatty acids can be catabolised to a common chemical substance called acetyl coenzyme A (acetyl CoA), which in turn is degraded to CO2 and H2). On the other hand, the carbon atoms of acetyl CoA, originally derived from hexoses, can be converted into fatty acids.