What is Cytosol?

DEFINITION: The cytosol is fluid that fills the cell and surrounds its organelles. The cytoplasm contains many enzymes, which are used for metabolism (chemical reactions in living organisms); it also contains ribosomes, which manufacture proteins through the translation of genetic information encoded in messenger RNA molecules; cytoskeletal proteins, which provide structural support; and motor proteins such as kinesin (which moves organelles such as mitochondria along microtubules) and myosin (which functions in muscle contraction).

History: Who discovered Cytosol?

The term “cytosol” was introduced for the first time by Lardy in 1965. He coined this word after breaking cells apart and pelleting all insoluble components (like membranes) using the ultracentrifugation method. Later it was discovered that this soluble cell fraction contains more than 90% of proteins and is called a cytoplasmic fraction.

What is Cytosol: Important Things To Note

1. It is a fluid that fills the cell and surrounds its organelles.
2. It contains many enzymes, which are used for metabolism (chemical reactions in living organisms).
3. It also contains ribosomes, which manufacture proteins through the translation of genetic information encoded in messenger RNA molecules.
4. It contains cytoskeletal proteins, which provide structural support; and motor proteins such as kinesin (which moves organelles such as mitochondria along microtubules) and myosin (which functions in muscle contraction).
5. Cytosol is very important for the healthy cell cycle of any organism.
6. It is a very important part of the cell, which helps in many processes during the life cycle of any organism.
7. The main component of the cytosol is water and it almost makes up 70% of its content.
8. It is very important in the process of energy metabolism in a cell, particularly when dealing with respiration and photosynthesis.
9. The main role of this fluid is to carry out the transport of material from one organelle to another.
10. Therefore, it also facilitates the process of cell division and mitosis that occurs in a cell during its life cycle.
11. Cytosol is also responsible for the movement of other components within it, especially that of membrane-bound molecules.
12. The cytosol also contains many other compounds such as lipids, sterols, and proteins which are not bound to membranes.

General Composition of Cytosol

The cytosol is a solution where all the components are dissolved in water. It consists of ions, small molecules and macromolecules like proteins and carbohydrates.

“The main component of the cytosol is water which comprises about 70% of it.”

This solution also contains many chemical substances like K+, Na+, Cl-, Mg2+, Ca2+, and bicarbonate. Moreover, it contains some other molecules like protein kinase C and calmodulin which are responsible for maintaining the osmolarity of the cytosol.

Cytosol Structure

The cytosol of a cell contains the fibrous molecules that form the cytoskeleton structure. The cytoskeleton gives a cell its shape and is involved in enabling organelles to move within a cell. It also facilitates the movement of a cell itself.

In addition, it has been estimated that more than 10,000 different kinds of molecules are involved in cellular biosynthesis (i.e., the process by which large molecules like proteins and DNA are synthesized from smaller ones).

Cytosol is the liquid inside a cell. It has various substances dissolved in it. Some of these are calcium, oxygen and ATP (Adenosine triphosphate).

The concentration of these substances can be affected by channels formed by protein complexes in the membrane and around organelles that affect their movement. Also, the channels formed by protein complexes can affect large particles from moving to other parts of the cytosol.

Functions of Cytosol

Cytosol has several functions including –

1. It plays several functions within a cell.
2. It helps in communication between the nucleus and cellular parts as well as organelles by providing signals to it.
3. It also transports metabolites from one place to other places in a cell for its metabolism.
4. It is required for cytokinesis, or cell division in plants and animals.
5. It also performs essential functions in metabolism such as glycolysis, gluconeogenesis, protein biosynthesis and pentose phosphate pathway in animal cells while plant cells produce fatty acids with the help of chloroplasts.

Cytosol vs Cytoplasm: What is the difference?

Cytosol is a term used in cell biology. Cytosol refers to the material that fills the space between organelles and nucleus of a cell. It contains dissolved ions, sugars, lipids and proteins which are suspended in water. The cytoplasm also extends around organelles within a cell. The nucleus of a cell is excluded from the cytosol. Cytosol is not the same as cytoplasm, although both are part of cell biology.

Main differences between Cytosol and Cytoplasm are –

1. Cytosol is a fluid that is present inside the cells of a plant or animal. On the other hand, cytoplasm refers to the material contained within the cell membrane of an organism.
2. The cytosol is made of a lot of water dissolved in ions, large water soluble molecules and proteins. In contrast, the cytoplasm contains organic constituents like nucleic acids, enzymes, lipids, non-organic ions etc. It also has amino acids and carbohydrates which are lightweight molecular compounds.
3. The metabolic activities of prokaryotes take place in the cytosol. The cytoplasm is mainly used for large scale cellular activities including cell division.

FAQ

What Does the cytosol contain?

Cytosol mainly contains –

• Water
• Proteins
• Small Molecules
• Dissolved Ions

This is what a Cytosol consists of. Cytosol is also made up of some large molecules that are non-protein with a molecular mass less than 300 Da (Dalton or Unified Atomic Mass Unit).

What is the other name of Cytosol?

Cytosol is also known by the names – Cytoplasmic Matrix and Groundplasm.

Do humans have a Cytosol?

Yes, human cells contain cytoplasm in which cytosol is a part.

Which cells have a cytosol?

Both Eukaryotic & Prokaryotic cells have a cytosol. So, plant cells, animal cells, and bacteria cells consist of cytosol.

What does cytosol look like?

Cytosol looks like a jelly-like fluid and its structure (cytoskeleton) looks like an organized framework of fibrous molecules.

Does Cytosol contain mitochondria?

No, Cytosol doesn’t contain mitochondria. Mitochondria & its contents are part of the Cytoplasm.

Do prokaryotes have cytosol?

Yes, prokaryotic cells (Bacteria Cells) have Cytosol.

Are proteins made in cytosol?

Proteins are made in Ribosomes which are a part of the cytosol. Ribosomes are cellular components that synthesize proteins. Each cell has many ribosomes, and the number of ribosomes present in a particular cell depends on its activity level with regards to protein synthesis.

Are ribosomes suspended in the cytosol?

Yes, some ribosomes called free ribosomes are suspended in the Cytosol. Proteins are the basic building blocks of every living cell. Ribosomes, which are tiny organelles, make proteins.

Free ribosomes make proteins that will be used in the cytosol (the watery part inside cells). Bound ribosomes on the other hand attach themselves to the outside of the endoplasmic reticulum (a membrane-bound part of the cell that helps in processing materials).

What are unattached ribosomes in the cytosol called?

Unattached ribosomes in Cytosol are generally called Free Ribosomes. On the other hand, the ribosomes that are attached to the endoplasmic reticulum are known as Bound Ribosomes.

Is cytosol and Hyaloplasm the same?

No, they are not the same. Hyaloplasm refers to just the name of the liquid of the Cytosol whereas Cytosol is the whole jelly-like fluid with water, ribosomes, and cytoskeleton of the cell.

How much cytosol is in a cell?

Cytosol makes up almost 70% of a cell.

What does cytoplasm have that cytosol lacks?

Cytosol lacks the nucleus, mitochondria, and endoplasmic reticulum which are present in the Cytoplasm of a cell.