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Cytoplasm – Structure and Function

Last Updated : 22 Sep, 2023
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Cytoplasm is a semi-fluid, gel-like substance found in all living cells, both prokaryotic and eukaryotic. It surrounds the cell’s organelles and nucleus. It acts as the medium in which various cellular processes like protein synthesis, metabolism, and many chemical reactions take place. The cytoplasm contains water, ions, nutrients, and various molecules necessary for cellular activities.

What is Cytoplasm?

Cytoplasm is the semi-fluid in consistency and is found in both prokaryotic and eukaryotic cells. It fills the space between the cell membrane and the nucleus and consists of ions, water, enzymes, and molecules essential for various of cellular activities. It serve as suspension medium for various cell organelles such as mitochondria, ribosomes, and the endoplasmic reticulum, that allow them to function effectively.

In the cytoplasm various metabolic reactions like glycolysis and protein synthesis take place. It allow the movement of molecules in and out of the cell through processes like diffusion and active transport.

Cytoplasm Definition

Cytoplasm is a semi-fluid substance found within cells. It includes all organelles except nucleus and plays a central role in various cellular processes, like metabolism and intracellular transport.

Structure of the Cytoplasm

The structure of the cytoplasm is as follows:

  • Cytosol is the the main component of the cytoplasm which is semi-fluid or gel-like in consistency. It forms the bulk of the cytoplasm.
  • Cytoplasm serves as a medium for various chemical reactions and suspends various organelles within it.
  • Cytoplasm contains various organelles including, endoplasmic reticulum (ER), mitochondria, golgi apparatus and vacuoles, etc.
  • The organelles present in the cytoplasm perform their specific functions.
  • The cytoskeleton consists of network of protein filaments that provide structural support to the cell and plays a role in cell motility, shape maintenance, and intracellular transport.
  • Enzymes are present in the cytoplasm that take part in various metabolic reactions and processes such as glycolysis, protein synthesis, and lipid metabolism.

Diagram of the Cytoplasm

The diagram of the cytoplasm is as follows:


Functions of the Cytoplasm

The functions of the cytoplasm are as follows:

  • Cytoplasm is a jelly like substance in which all the components of the cells are embedded. It is present within the cell membrane and is made up of salt and water.
  • It serves as the site for numerous metabolic reactions like glycolysis, which produces energy in the form of ATP.
  • The cytoplasm supports the cytoskeleton, which gives the cell its shape and motility to the cell.
  • It act as a medium for intracellular movement of molecules and organelles. The movement take place through processes like diffusion and active transport.
  • Cytoplasm stores various cellular materials, like nutrients, ions, and waste products.
  • Protein synthesis occur in the cytoplasm, through translation, where ribosomes assemble amino acids into proteins.
  • Signaling molecules and organelles present in it enables cellular communication.

Organelles in the Cytoplasm

The various cell organelles present in the cytoplasm are as follows:


It is the biggest organelle and serves as the command center for cellular operations as well as the DNA repository for the cell. The nucleolus, or small spherical entities, are found inside the nucleus. It also contains chromosomes and genes that are carried by chromosomes. The nucleus manages the traits and operations of our body’s cells. Using the genetic information contained in DNA, the nucleus’ main job is to keep track of cellular functions like metabolism and growth. Protein and RNA synthesis takes place in the nucleus of the nucleoli.



As it generate energy in the form of ATP for the cell, mitochondria are referred to as the powerhouses of the cell. In many species, the mitochondrial genome is transmitted from the mother. It is a sausage-shaped organelle with two membranes linked to it that is present in practically all eukaryotic cells.


Endoplasmic Reticulum

The Endoplasmic Reticulum is a network of fluid-filled membranous tubes. They are the cell’s transport system and are responsible for moving materials around the cell.


The endoplasmic reticulum comes in two varieties:

  • The production of proteins is carried out by the rough endoplasmic reticulum, which is made up of cisternae, tubules, and vesicles.
  • Smooth Endoplasmic Reticulum: This organelle serves as a storage area and is involved in the synthesis of lipids and steroids, as well as the detoxification of the cell.


Membrane-bound organelles called plastids hold pigment. Plastids can be classified into three groups based on the sort of pigments they contain:

  • Chloroplast: Chloroplasts are dual membrane-bound organelles present in the mesophyll cells of leaves. The photosynthetic process depends on the pigments’ ability to store light energy. The stroma of chloroplasts likewise has dual circular DNA, 70S ribosomes, including enzymes necessary for the production of carbs, similar to the mitochondrial matrix does.
  • Chromoplasts: This comprises low-saturated carotene compounds, such as xanthophylls and carotene, which give plants their distinctive colors, such as yellow, and red.
  • Leucoplasts are colorless plastids that serve as food storage. Aleuroplasts retain proteins, elaioplasts hold oils and lipids, and amyloplasts hold carbs (such as the starch in potatoes).


In close proximity to the endoplasmic reticulum are ribosomes, significant non-membrane-bound cytoplasmic organelles. Numerous cells have microscopic particles called ribosomes, which are primarily made up of 2/3 RNA and 1/3 protein. They are referred to as the 70s or the 80s (found in prokaryotes) (found in eukaryotes) Either the endoplasmic reticulum encloses ribosomes or they are freely dispersed throughout the cytoplasm of the cell. In all living cells the function of the ribosomes is to synthesize proteins.

Golgi Apparatus


The Golgi Apparatus is a membrane-bound organelle made up of cisternae, which are a series of flat, piled pouches. Proteins and lipids are transported, and packaged by this organelle to reach specific locations.


The cytoskeleton consists of protein filaments found in the cytoplasm of eukaryotic cells. The cytoskeleton provides structural support to the cell, helps maintain cell shape, and is essential for intracellular transport, cell motility, and cell division.

Centrosome and Centriole

The centrosome found in animal cells, consists of two centrioles. They are cylindrical structures composed of microtubules. Centrioles takes part in cell division, and organize and direct the formation of the mitotic spindle, that ensures accurate chromosome segregation.

FAQs on Cytoplasm

1. What is Cytoplasm?


Cytoplasm is the semi-fluid, gel-like substance found inside cells. It provides the cellular environment where various metabolic and cellular processes take place.

2. What is the Function of Cytoplasm?


Cytoplasm plays a central role in suspending various cell organelles, facilitating metabolic reactions, and supporting cellular processes like glycolysis, protein synthesis and intracellular transport.

3. What is the Composition of Cytoplasm?


Cytoplasm is mainly composed of water, ions, proteins, enzymes, and various molecules required for various cellular structure and functions.

4. What are Organelles Found within the Cytoplasm?


Organelles like the endoplasmic reticulum, Golgi apparatus, mitochondria, ribosomes, and vacuoles are suspended within the cytoplasm.

5. How does the Cytoplasm Support Cellular Structure?


The cytoskeleton, a network of protein filaments within the cytoplasm, provides structural support and shape to the cell, and facilitates cell motility.

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