A cell is the smallest functional unit of all living organisms. A cell is also called the structural and fundamental unit of all the living species. It is mainly involved in carrying out numerous important biological activities of a living organism.
Every living organism existing on this planet Earth is composed of cells. The total number of cells in living species generally vary from one to trillions. Many species exist with one cell, called unicellular organisms, and few are composed of millions to billions of specialised cells, called multicellular species.
The term cell was initially derived from the Latin word “cella”, meaning a small room.
What are Cell Organelles?
The human body comprises about 30-38 trillion cells, mainly involved in specialised functions. All these functions are carried out by a group of specialised organelles present within the cell.
Cell organelles are the structural and functional units of the cell. These specialised organelles are also called the components of cells, which helps in keeping the cell alive and active.
In living cells, the cell organelles are of three types and are classified based on the presence or absence of the membrane.
- Organelles without membrane – Cell wall, cytoskeleton, and ribosomes lack membrane. Hence they are classified into non-membrane-bound cell organelles.
- Single membrane-bound organelles – Endoplasmic Reticulum, Golgi apparatus, lysosome and vacuoles are bounded with a single membrane layer.
- Double membrane-bound organelles – Chloroplast, mitochondria and nucleus are bound with a double membrane layer.
Other than these three categories, there is a specialised cell membrane, which is also called the plasma membrane. It is a semi-permeable membrane of the cell, which allows the entry and exit of only selected substances in and out of the cell.
Functions of Cell Organelles
All cell organelles have their specialised functions to keep cells active and alive throughout their lifespan.
Listed below are the functions of some essential cellular organelles.
- Cell Wall is the outermost cellular organelle, which is present only in plants, bacteria, algae, and fungi.
- They are mainly involved in providing structural support, rigidity and protection to the inner layer of the cell.
- It is a double-membrane, the most prominent organelle found in plants, animals, and eukaryotic cells.
- The nucleus acts as the control centre of cellular activities and stores the cell’s DNA.
It is a double-membrane and an oval-shaped cell organelle, mainly responsible for cellular respiration. Mitochondria are found both in plants, animals and in all eukaryotic cells. Mitochondria are called “energy currency of the cell” as it stores energy in the form of adenosine triphosphate molecules (ATP).
- Golgi apparatus is also called Golgi complex or Golgi bodies.
- It is a single membrane-bound organelle found both in plants, animals, and all eukaryotic cells.
- The Golgi body functions by modifying and transporting proteins and lipids to targeted destinations. Hence, it is also termed as “postman of the cell”.
- The cytoplasm is a jelly-like substance found in plants, animals, and all eukaryotic cells.
- Cytoplasm comprises dissolved nutrients, water, and other cell waste products.
- This cell organelle is mainly responsible for cellular metabolic activities.
- Endoplasmic reticulum is a network of membranous tubules present within the cytoplasm of a cell.
- This cell organelle forms a skeletal framework of the cell.
- Endoplasmic reticulum is also involved in removing toxins or detoxifying the cells, and producing proteins and Lipids.
These are a few pieces of information related to the cell and its organelles. There are more interesting facts and information related to the cell, types of cells, their organelles, and more.
Stay tuned with BYJU’S Biology, to learn more about the different Biology concepts and learn by watching interactive videos by subscribing to BYJU’S YouTube Channel.