Assimilation in biology is a crucial metabolic process in which absorbed nutrients are transformed into complex biomolecules that become an integral part of an organism’s cellular structure and function. It occurs after digestion and absorption, ensuring that essential macromolecules—such as carbohydrates, proteins, and lipids—are synthesized and utilized for growth, repair, and maintenance of bodily functions.
For instance, monosaccharides like glucose, derived from carbohydrate digestion, enter cells via facilitated diffusion or active transport. Once inside, glucose undergoes glycolysis, the Krebs cycle, and oxidative phosphorylation to generate ATP, which fuels cellular activities. Similarly, amino acids absorbed from dietary proteins are assimilated into cells and serve as precursors for protein synthesis, supporting enzymatic reactions, muscle development, and tissue repair. Fatty acids and glycerol, obtained from lipid digestion, are reassembled into triglycerides and stored in adipose tissue or utilized in membrane synthesis and energy production.
In plants, assimilation primarily involves the conversion of inorganic carbon (CO₂) into organic compounds via photosynthesis. Through the Calvin cycle, CO₂ is fixed into glucose, which serves as a fundamental energy source and structural component in cellular processes. Additionally, nitrogen assimilation enables plants to incorporate inorganic nitrogen (from nitrates or ammonium) into amino acids and nucleotides, essential for protein and DNA synthesis.
Overall, assimilation is a fundamental process that integrates absorbed nutrients into the biochemical pathways of an organism, ensuring proper growth, energy production, and homeostasis.
Examples of biological assimilation
*
Photosynthesis
Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...
, a process whereby
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
and
water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
are transformed into a number of
organic molecules in
plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...
cells.
*
Nitrogen fixation
Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...
from the soil into organic molecules by
symbiotic
Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...
bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
which live in the
root
In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often bel ...
s of certain plants, such as
Leguminosae
Fabaceae () or Leguminosae,[International Code of Nomen ...](_blank)
.
* Magnesium supplements orotate, oxide, sulfate, citrate, and glycerate are all structurally similar. However, oxide and sulfate are not water-soluble and do not enter the bloodstream, while orotate and glycerate have normal exiguous liver conversion. Chlorophyll sources or magnesium citrate are highly bioassimilable.
* The
absorption of
nutrient
A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
s into the body after
digestion
Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into th ...
in the
intestine
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...
and its transformation in
biological tissue
In biology, tissue is an assembly of similar cells and their extracellular matrix from the same embryonic origin that together carry out a specific function. Tissues occupy a biological organizational level between cells and a complete or ...
s and
fluid
In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...
s.
See also
*
Anabolism
Anabolism () is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units. These reactions require energy, known also as an Endergonic reaction, endergonic process. Anabolism is the building-up aspect of metabo ...
*
Biochemistry
Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, a ...
*
Nutrition
Nutrition is the biochemistry, biochemical and physiology, physiological process by which an organism uses food and water to support its life. The intake of these substances provides organisms with nutrients (divided into Macronutrient, macro- ...
*
Respiration
*
Transportation
Transport (in British English) or transportation (in American English) is the intentional Motion, movement of humans, animals, and cargo, goods from one location to another. Mode of transport, Modes of transport include aviation, air, land tr ...
*
Excretion
Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, Kidney (vertebrates), kidneys, and skin. This is in contrast with secretion, where the substa ...
References
{{Authority control
Biological processes
Metabolism