Difference Between Cytosol and Cytoplasm

Key difference - cytosol vs. cytoplasm

The cytosol and cytoplasm are two parts of the cell. Cytosol is part of the cytoplasm. It is the intracellular fluid in the cell. Most metabolic reactions take place in the cytosol. Water is the most abundant element in both the cytosol and the cytoplasm. The main difference between cytosol and cytoplasm is that cytosol is a part of the cytoplasm of a cell, while cytoplasm is a part of the cell that is surrounded by the cell membrane.

This article examines

1. What is cytosol - composition, properties, function, organization 2. What is cytoplasm - composition, properties, function, organization 3. What is the difference between cytosol and cytoplasm

Difference Between Cytosol and Cytoplasm - Summary of Comparison

What is the cytosol?

The cytosol is a fluid that is considered to be the matrix of the cytoplasm. This fluid consists of intracellular fluid and is divided by the cell membrane into mitochondrial matrix, chloroplast stroma-like structures. In eukaryotes , the cytosol is part of the cytoplasm. It surrounds the organelles in the cytoplasm. In prokaryotes, metabolic reactions take place in the cytosol. Most eukaryotic metabolic reactions take place in the organelles rather than in the cytosol.

Composition and properties of cytosol

The cytosol consists primarily of water, small and large soluble molecules, and dissolved ions. It dissolves non-protein molecules less than 300 Da in size. In the cytoplasm of the plant cell, around 200,000 different small molecules can be dissolved in the cytoplasm. Water makes up about 70% of the total volume of the cytosol. Thus, the pH of the cytoplasm is in the range of 7.0-7.4. The viscosity is also similar to that of water. But diffusion through the cytosol can be four times slow for the small molecules. Through osmosis , water constantly gets into the cytosol. The concentration of calcium ions in the cytosol is only <0.0002 mM, which means that the calcium ions can act as a second messenger substance in signaling pathways.

The cytosol contains a comparatively large number of charged macromolecules such as proteins and nucleic acids. The amount of protein dissolved in the cytosol is about 200 mg / ml. In the cytosol there is a complex mixture of cytoskeleton filaments, which consists of microtubules and actin filaments. These filaments form a network of cytoskeleton. The filament network and the higher concentration of macromolecules contribute to the macromolecular crowding effect in the cytosol. Due to this effect, Cytosol changes its properties compared to an ideal solution. The overcrowded solution of cytosol by different types of molecules is shown in Figure 1.

Key difference - cytosol vs cytoplasm

Figure 1: Macromolecular crowding


The cytosol consists of a concentration gradient of some molecules, although most of the small molecules are evenly distributed. For example, a calcium ion gradient is created through the opening of the calcium channels, which only lasts for milliseconds. Multiple calcium gradients spark to form a large calcium gradient known as calcium waves. In addition, protein complexes are formed in the cytosol, which enable the substrate to be channeled, in which a product is passed directly to the next step. Some of these complexes also consist of a large, isolated, central cavity like the proteosome. These protein compartments contain proteases that break down cytosolic proteins. Another example of a protein compartment are microcompartments in bacteria that have a diameter of 100 to 200 nm. Carboxysome is a type of microcompartment that is involved in carbon fixation. The cytoskeleton screening concentrates ribosome- like organelles in a specific area by excluding compartments. These exclusive compartments are made up of denser actin fibers.

Function of cytosol

The cytosol contributes to the transmission of signals from the cell membrane to the site of action, usually to the cell nucleus . The transport of metabolites from place to place is facilitated by the cytosol. Amino acids diffuse freely from the cytosol like small soluble molecules. Large hydrophobic molecules such as sterols and fatty acids are transported by binding to specific proteins. The endocytosed molecules are transported through vesicles in the cytosol. The prokaryotic metabolism also takes place in the cytosol. In animals, translation, glycolysis, the pentose phosphate pathway, and gluconeogenesis occur in the cytoplasm.

What is the cytoplasm?

The cytoplasm is the part of a cell that is surrounded by the cell membrane. The cytosol is part of the cytoplasm. In addition to the cytosol, the cytoplasm contains organelles. In prokaryotes, all cell structures are embedded in the cytoplasm. The organelles suspended in the cytoplasm are shown in Figure 2 .

Difference Between Cytosol and Cytoplasm

Figure 2: Cytoplasm with organelles: 1. Nucleolus 2. Nucleus 3. Ribosome 3. Vesicle 5. Coarse endoplasmic reticulum 6. Golgi apparatus 7. Cytoskeleton 8. Smooth endoplasmic reticulum 9. Mitochondrion 10. Vacuole 11. Cytosol 12. Lysosome 13th Centriole

Composition and properties of cytoplasm

Cell signaling by the cytoplasm depends on the permeability of the cytoplasm. It depends on the diffusion of the signaling molecule through the cytoplasm. Small signal molecules such as calcium ions diffuse through the cytoplasm. The cytoplasm also acts as a sol-gel, sometimes as a liquid (sol) and sometimes as a solid mass (gel). The motor proteins in the cytoplasm lead to the non-Brownian movement of the particles in the cytoplasm.

The cytoplasm consists of the cytosol, its organelles and cytoplasmic inclusions. Organelles in the cytoplasm include the nucleus, mitochondria , Golgi apparatus, endoplasmic reticulum , lysosomes, and in plant cells, vacuoles and chloroplasts . Some insoluble particles suspended in the cytoplasm are called cytoplasmic inclusions. Particles such as calcium oxalate, granules such as starch and glycogen, and lipid droplets are known to be inclusions in the cytoplasm.


The inner area of ​​the cytoplasm is concentrated and is called the endoplasm. The outer area of ​​the cytoplasm is called the cell cortex or ectoplasm.

Function of the cytoplasm

The cytoplasm is involved in major cellular activities such as glycolysis and nuclear division. The solid glass structure of the cytoplasm freezes large organelles in place. The cytosol is also involved in cytokinesis, which is the process of cytoplasmic division followed by nucleus division. In addition, the functions of the cytosol are also taken over by the cytoplasm.

Difference Between Cytosol and Cytoplasm


Cytosol: Cytosol is the fluid that is present in the cell membrane.

Cytoplasm: Cytoplasm is the cell component within the cell membrane.


Cytosol: The cytosol is made up of water, soluble ions, small and large water-soluble molecules, and proteins.

Cytoplasm: The cytoplasm consists of 80% water, nucleic acids, enzymes, lipids, amino acids, carbohydrates and non-inorganic ions.


Cytosol: The diversity of the cytosol is low.

Cytoplasm: The diversity of the components is high compared to the cytosol.


Cytosol: The components of the cytosol are water, soluble small and large molecules.

Cytoplasm: The components of the cytoplasm are organelles, cytosol and cytoplasmic inclusions.


Cytosol: All chemical reactions occur in the cytosol on prokaryotes.

Cytoplasm: The cytoplasm is involved in major cellular activities such as glycolysis and cell division.


Cytosol: The cytosol concentrates its dissolved molecules in the right positions for efficient metabolism.

Cytoplasm: The cytoplasm freezes organelles in place, ensuring efficient metabolism.

Additional functions

Cytosol: The signal transmission and the transport of molecules take place in the cytosol.

Cytoplasm: Nuclear division, cytokinesis and signal transduction take place in the cytoplasm .


Both cytosol and cytoplasm together form the dynamic solution within the cell. The cytoplasm, which is the transparent part of both prokaryotic and eukaryotic cells, is a semi-solid liquid. The cytoplasm makes up the liquid part of the cytoplasm. Thus, the diversity of both soluble and insoluble particles in the cytoplasm is high. Components of the cytoplasm include organelles, cytosol, and cytoplasmic inclusions. Organelles such as the nucleus, mitochondria, Golgi apparatus and particles such as crystals, granules and lipid droplets are suspended in the cytosol. Most of the metabolic pathways in prokaryotes take place in the cytosol, and some of the reactions, such as glycolysis in eukaryotes, take place in the cytosol. Cellular activities such as cell division and cytokinesis take place in the cytoplasm. Molecules are concentrated in the right parts of the cytoplasm by the cytosol and organelles are frozen in the right places in the cell by the cytoplasm. All of these features suggest that the main difference between the cytosol and the cytoplasm is their proportionality to the size in the cell.

Reference: 1. "Cytosol." Wikipedia. Np: Wikimedia Foundation, January 26, 2017. Web. March 6, 2017.2. "Cytoplasm." Wikipedia. Np: Wikimedia Foundation, March 6, 2017. Web. March 6, 2017. 3. “Structural Biochemistry / Cell Organelles / Cytosol.” Wikipedia. Np: Wikimedia Foundation, Oct. 23, 2017. Web. March 6, 2017.

Image courtesy: 1. "Crowded Cytosol" By TimVickers - Own work by Uploader, based on similar illustrations in Goodsell DS (June 1991). "Inside a living cell". Trends Biochem. Science 16 (6): 203-6. DOI: 10.1016 / 0968-0004 (91) 90083-8. PMID 1891800. (Public Domain) via Commons Wikimedia 2. “Biological Cell” By MesserWoland and Szczepan1990 - Own work (Inkscape created) (CC BY-SA 3.0) via Commons Wikimedia

About the author: Lakna

Lakna, a graduate in molecular biology and biochemistry, is a molecular biologist and has a broad and strong interest in discovering things related to nature