Anabolism definition

Anabolism is a biochemical process in metabolism where the simple molecules combine to generate complex molecules. This process is endergonic, which means it is not spontaneous and requires energy to progress the anabolic reaction. The complex molecules obtained are further used to store energy in the form of ATP (Adenosine Tri Phosphate).

Anabolism example

Cells use an anabolic process to make polymers, repair, and grow tissues. For example:

    • Formation of disaccharides and water with the help of combining simple sugars

C6H12O6 + C6H12O6 → C12H22O11 + H2O

    • Formation of dipeptides by combining Amino acids


    • Formation of lipids when glycerol reacts with fatty acids


    • Process of photosynthesis to form glucose and oxygen

6CO2 + 6H2O → C6H12O6 + 6O2

Some examples of anabolic hormones are

  • Insulin – It promotes absorption of glucose
  • Anabolic steroids – It helps in stimulating muscle growth
  • Anaerobic exercise – It helps in building muscle mass

Stages of anabolism

There are three stages in anabolism. They are

  1. Production of precursors such as monosaccharides, nucleotides, amino acids, and isoprenoids.
  2. Activation of the above-mentioned precursors into reactive forms with the help of energy from ATP.
  3. Assemble the precursors to form complex molecules such as polysaccharides, nucleic acids, proteins, and lipids.

Energy source for anabolic processes

Various species depend on various sources of energy. A few have been discussed below:

  • Autotrophs – Formation of complex organic molecules such as proteins and polysaccharides in plant cells from simple molecules like water and carbon dioxide with the help of sunlight as an energy source.
  • Heterotrophs – They require complex substances such as amino acids and monosaccharides to produce these complex molecules.
  • Photoheterotrophs and photoautotrophs – They obtain energy from light
  • Chemoheterotrophs and chemoautotrophs get energy from inorganic oxidation reactions.

Anabolism functions:

The nutrients from food are broken down into small blocks in the catabolic pathway. Macromolecules are formed when small molecules are combined. During the anabolic pathway, energy is utilized to generate large molecules by forming chemical bonds between the smaller molecules. These macromolecules are further used to build new cells or structure the cells. Anabolism is essential for maintenance, growth, and development of a cell.

DNA synthesis

DNA (Deoxyribonucleic acid), is a macromolecule which is made up of smaller molecules known as nucleic acids. These nucleic acids are made up of a nucleotide base attached to a phosphate and deoxyribose sugar molecule. DNA synthesis takes place in the nucleus of the cell before cell division.

It involves the following steps:

  • Unzipping the double-stranded DNA
  • Attaching new matching nucleotides to each strand to form two new strands