Cytosol Function And Structure:Why,How And Detailed Insights

Cytosol is one of the major intracellular fluids (ICF), acting as the matrix part of a cell. Here we are going to discuss cytosol functions and structure inside the cell.

As a medium of most of the cellular activities, the cytoplasm performs several functions inside the cell.

  • The cytosol is the cytoplasmic semi-fluid matrix, consisting of several micro and macro bio molecules. With these components of cytosol, it makes a cellular organization and gives structural support to the cell.
  • The cytosol is the main platform for all enzymatic activities within cells. It contains several cellular enzymes and acts as a medium in their activities.
  • In signal transduction procedure, the role of cytosol is immense. The cytosol transport metabolites from their production site to their destinations. 
  • Cytosol performs a significant role in osmoregulation. It contains several inorganic ions which regulate and maintain the osmotic pressure in the cell.
  • The cytosol contains trehalose, an osmoprotectant which helps to survive the cell during adverse situations. It protects all the cellular organelles and biomolecules by turning the cytosol into solid.
  • Cytosol has a major role in generating and maintaining the action potential of the cell.
  • After the division of the membrane, the cytosol performs a significant role in the cytokinesis process and stimulates cell division.
  • In the endocytosis process where metabolites from outside of the cell enters, the cytosol helps to bring them in.
  • Most of the metabolic activities like protein biosynthesis, Pentose phosphate pathway, glycolysis, gluconeogenesis,etc takes place in the cytosol of the cell.
  • Growth and expandation of a cell also depends on the cytosol part of that cell.

Apart from these there are several more cytosol functions included, such as assisting cytoplasm streaming, ion channels maintaining,  etc.

cytosol function,cytosol structure

Cytosol function from Wikimedia

Cytosol Structure

The cytosol is typically a mixture of  ions, small molecules,large water-soluble molecules and water. However, a structural organization can be seen within cytosol. Let’s have a closer look at it.

Concentration Gradient

In this portion of cytosol, small molecular sparks can be produced such as calcium spark, oxygen spark or adenosine triphosphate, etc. These sparks are few micrometers in length and lasts upto only a few milliseconds. These sparks mostly arise from the site near to mitochondria.

Protein complexes

It is an organization of protein associates, where the proteins contain functional similarities. The association of protein complexes allows substrate channeling, important for metabolic pathways. Most enzymes related to the same metabolic pathway are associated to form the protein complexes.

Protein compartments

Protein compartments are a large central association of protein substances. Some common protein compartments are proteasome, containing proteases which can cause degradation of other cytosolic protein elements. Carboxysome compartment contains enzymes necessary for the carbon fixation process.

In case of prokaryotic cells where the organelles lack membrane bound structure, some macromolecules around them undergo  clustering or polymerization and form an organization called biomolecular condensates. 

The cytoskeleton is not considered a part of cytosol but its presence influences the cytosol structure. The cytoskeletal filaments restrict the diffusion of large particles of cytoplasm.

Cytosol Composition

The cytosol is an unequal mixture of several components like water, ions, micro molecules, macromolecules, etc. At different Parts of cytosol the component amounts vary randomly.


The cytosol consists of about 79% of water in it. The pH of the cytosolic water is 7.4. The viscosity of this is the same as the pure water. The cytosolic water influences most metabolic activities within the cytoplasm. 

Inorganic and organic Ions

The cytosol consists of several inorganic ions in it. The amount of these ions differs from in other extracellular fluids. It contains potassium (139-150 millimolar), sodium (12 millimolar), chloride (4 millimolar), bicarbonate (12 millimolar), amino acids (138 millimolar), etc. It also has some amount of magnesium and calcium in it.

Micro And Macro Molecules

About 20%-30% of cytosol consists of protein molecules in it. These protein molecules are mostly enzymes involved in various  metabolic pathways. In case of prokaryotic cells the cytosol also contains the genome of the cell or the nucleoid. Related to these genetic material, replication and transcription enzymes (protein) are also available in the prokaryotic Cytosol.

To know more about DNA replication read our article on DNA Replication Steps and Critical FAQs

Cytosol Location

In case of eukaryotic cells the cytosol is located between the space of cytoplasmic membrane and nuclear membrane. It is the part of cytoplasm avoiding the membrane bound organelles,cytoskeleton and inclusions. 

In case of prokaryotic cells the cytosol is located inside the cytoplasmic membrane. The genome or nucleoid is a situation within the cytosolic matrix of a cell.

To know more about eukaryotic cells read our article on Eukaryotic Cells Examples: Detailed Insights

Cytosol Vs Cytoplasm

The cytosol is a component of cytoplasm itself. Let’s try to find out the difference between them.

TopicCytosolCytoplasmDefinitionThe cytosol is a fluid component of cytoplasm present in cells. The cytoplasm is the component of the cell present inside the cell.
CompositionIt contains ions, water and water soluble proteins. It contains enzymes, lipids, nucleic acids, carbohydrates, ions, etc.
Involved in Metabolic reaction takes place in cytosol. Glycolysis, cell division, etc takes place in cytoplasm.
Main function Transportation of molecules and signal transduction is the main function of Cytosol. The main function of Cytoplasm is to hold all the cellular organelles and other molecules within it, Give protection and serve like a medium of all metabolic reactions.
Components Water, ions and large water soluble molecules are the major components of cytosol. Cytosol, membrane bound organelles and cytoplasmic inclusions are the major components of cytoplasm.
Diversity The diversity is low in case of cytosol. The diversity is high in case of cytoplasm.
Difference between cytosol and cytoplasm
0312 Animal Cell and Components 1

Cytoplasm from Wikimedia

How Does Cytosol Function?

The importance of cytosol in cellular activities is immense. It performs several functions inside the membrane. 

The cytosol is the semifluid gel-like matrix which gives the cellular components structural support. It transports molecules from one to another place of the cell and helps in signal transduction procedure. In prokaryotes it contains the nucleoid and serves as a medium of replication and transcription process.

The components of cytosol are highly related to the efficiency of all metabolic pathways. 

How Many Coenzymes Are Reduced In Cytosol?

During the glycolysis process two acetyl coenzymes are reduced in cytosol.

Here we describe the cytosol function and cytosol structure briefly. We mention the composition of the cytosol. We also state the difference between the cytosol and the cytoplasm of a cell. We also find out how the cytosol functions within the cell. Lastly we can say the role of cytosol in cellular activities is immense.

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