Structure and function of cytoplasm reveals the importance of thick liquid material present inside a eukaryotic cell.
What is the cytoplasm?
The cytoplasm is made up of two words “cyto” and “plasm”. The word “cyto” means "cell" while the “plasm” means "fluid or liquid".
The cytoplasm is the thick solution present inside the cell from the cell membrane to the nucleus. The liquid material present inside the nucleus is the nucleoplasm.
The cytoplasm is made up of 80% water, while 20% part consists of salts, proteins, carbohydrates, and lipids. Salt is inorganic while proteins, carbohydrates, and lipids are organic substances giving cytoplasm colorless appearance.
Structure of cytoplasm
The cytoplasm consists of three main parts
- Cytosol
- Organelles
- Cytoplasmic inclusions
1. Cytosol is a gel or jelly-like part of the cytoplasm in which proteins, organelles, and other materials float.
2. Organelles are sub-cellular structures present inside the cell and perform various functions for the cell such as endoplasmic reticulum, Golgi apparatus, nucleus, and vacuoles.
3. Cytoplasmic inclusions are non-living and non-membrane-bounded substances present inside the cell. They may be some part of nutrients, pigments, or secretory products.
The cytoplasm may appear unorganized and random under the microscope but in reality, it is a highly organized structure. Just like the bones inside the body which gives shape and support to the body similarly inside the cytoplasm specific filaments and tubules are present to provide the shape and support to the cells known as the cytoskeleton.
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| Structure of cytoplasm. Image created in BioRender.com |
Cytoskeleton
The cytoskeleton is a scaffold of protein which means that it is made up of different types of proteins. The cytoplasm contains three different types of proteins
- Microfilaments
- Microtubules
- Intermediate filaments
1. Microfilaments are made up of actin protein and present next to the cell membrane. They are the thinnest in size and are very helpful for the cell in changing its shape.
2. Microtubules are made up of tubulin protein, hollow from inside, and extend from one part of the cell to another part of the cell. They are thickest in size and help maintain the shape of the cell.
3. Intermediate filaments are in between the microfilaments and microtubules in size. The main function of intermediate filaments is holding the tissues together. The composition of intermediate filaments varies according to their function or presence e.g., keratin protein is present in filament present in hair and nails.
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Function of cytoplasm
The main functions of cytoplasm are:
- Most cellular activities take place inside the cytoplasm. For the cellular activities to takes place, water is very important and 80% of cytoplasm is made up of water so it is the best site for the cellular reactions to takes place.
- Many metabolic pathways take place inside the cytoplasm e.g., glycolysis which is the breakdown of glucose into small molecules to generate energy.
- Other processes such as cell division also take place in the cytoplasm.
- The other function of cytoplasm is the movement of ions in or out of the cell.
Some question and answer
Q. What is the difference between cytoplasm and nucleoplasm?
A. Cytoplasm is the thick solution present inside the cell from cell membrane to nucleus, while nucleoplasm is the liquid part present inside the nucleus from nuclear membrane to nucleolus. The composition of both solutions are different according to their functions.
Q. Why cytoplasm is made up of 80% water?
A. Water is very important for chemical reaction to take place. As most of the chemical reactions take place inside the cytoplasm so water presence in cytoplasm helps in smooth functioning of cell.
Q. What is the difference between cytoplasm and protoplasm?
A. Normally, both terms are interchangeably used in literature. However, the cytoplasm is referred to thick solution present inside the cell from the cell membrane to the nucleus, while the protoplasm includes cytoplasm and nucleus.
Q. State three functions of cytoplasm.
A. It is a site of many metabolic process, involved in cell division and allows movement of ions through cytoplasmic streaming.
Q. What is cytoplasmic streaming?
A. Cytoplasmic streaming is the movement of cytoplasm within a cell caused by cytoskeleton forces. Its function is most likely to speed up the transportation of molecules and organelles across the cell.
Q. What are the main parts of the cytoplasm?
A. The three main parts of cytoplasm include cytosol, organelles, and cytoplasmic inclusions.
Q. What is the composition of cytoplasm?
A. The cytoplasm is made up of 80% water, while the 20% part consists of salts, proteins, carbohydrates, and lipids. Salt is inorganic while proteins, carbohydrates, and lipids are organic substances giving cytoplasm a colorless appearance.
Q. Differentiate between cytoplasm and cytosol.
A. Cytoplasm is the thick solution present inside the cell from cell membrane to nucleus, while cytosol is gel or jelly-like part of the cytoplasm in which proteins, water, organelles, cytoskeleton and other dissolved substances are present.
References
- Crick, F. H. C., & Hughes, A. F. W. (1950). The physical properties of cytoplasm. Experimental Cell Research, 1(1), 37-80.
- Luby-Phelps, K. (1994). Physical properties of cytoplasm. Current opinion in cell biology, 6(1), 3-9.
- Shimmen, T., & Yokota, E. (2004). Cytoplasmic streaming in plants. Current opinion in cell biology, 16(1), 68-72.
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