What is anabolism?

Anabolism is the constructive processes of metabolism. It concerned with the formation of complex molecules from simple precursors with the utilization of free energy. For example, amino acids are simple molecules, build complex molecules of proteins through a series of anabolic reactions that build up our bodies muscle.

The purpose of anabolism is to synthesis the complex molecules that build up our bodies by utilizing the ATP energy that arise from the catabolic reactions.

Anabolic reactions comprises three basic stages. Firstly, the generation of precursors such as glucose, amino acids and fatty acids. Secondly, their activation into reactive forms. Finally, the assembly of these reactive forms converted into complex molecules of carbohydrate, protein or lipid that help build up our bodies including our muscle, fat, and bone.

Major anabolic reactions in our bodies:

Carbohydrate anabolism:

Glycogenesis – synthesis of glycogen from glucose is called glycogenesis.
Gluconeogenesis – it is the synthesis of carbohydrates from non carbohydrates precursors such as pyruvate, lactate, glycerol, and glucogenic amino acids.
Protein anabolism:

Protein synthesis – Protein is synthesized from the amino acids through a series of anabolic reactions.
Urea cycle – Most of the toxic ammonia synthesized from the deamination of amino acids in the liver are converted into non-toxic urea by the process of urea cycle. From the liver urea is transported to kidney for disposal.
Lipid anabolism:

Lipogenesis (Synthesis of fatty acid) – fatty acids may be synthesized from acetyl CoA derived from glucose or amino acids metabolism by the process of lipogenesis.
Ketogenesis (Formation of ketone bodies) – Acetyl CoA arise from β-oxidation of fatty acid is used to synthesis of ketone bodies in the liver by the process of ketogenesis.
Cholesterol synthesis – Cholesterol is synthesized from acetyl CoA arises from β-oxidation of fatty acid.
Triglyceride synthesis – Triglyceride is synthesized by the esterificaton of free fatty acids with glycerol, which is stored in the adipose tissue.
Steroid synthesis – Steroid is synthesized from acetyl CoA arises from β-oxidation of fatty acid.