What is a Cell ? Definitions, types and functions ?
“A cell is defined as the smallest, fundamental unit of life, responsible for all life processes.”
Cells are the basic, fundamental unit of life. Thus, if we were to dissect an organism down to the cellular level, the cell would be the smallest independent component we would find.
The cytoplasm is an essential fluid in each cell, encompassed by a membrane, with biomolecules like nucleic acids, proteins, and lipids uniformly dispersed within. Suspended in the cytoplasm are cell organelles, vital for complex cellular functions.
Every cell contains a fluid called cytoplasm, which is surrounded by a membrane. Some biomolecules such as proteins, nucleic acids and lipids are also present in the cytoplasm. Furthermore, cellular structures called organelles are suspended in the cytoplasm.
Cells are the structure and basic unit of life. The study of the basic structure of a cell to the function of each organelle is called cell biology. Robert Hooke was the first biologist to discover the cell.
All living organisms are composed of cells. They can consist of a single cell (unicellular) or many cells (multicellular). Mycoplasma is the smallest known cell. Cells are the building blocks of all living things. They give the body structure and convert nutrients absorbed from food into energy.
Types of Cells:
The difference between Prokaryotic and Eukaryotic Cells:
|Prokaryotic cell||Eukaryotic cell|
|1. Size is 0.1- 5.0 micrometers.||1. Size is 5-100 micrometers.|
|2. Nucleus is absent.||2. Nucleus is present.|
|3. They are unicellular organisms.||3. They are unicellular or multicellular|
|4. It contains a single chromosome.||4. It contains more than one chromosome.|
|5. Cell division occurs only by mitosis.||5. Cell division occurs only by mitosis and meiosis.|
|6. Mitochondria absent.||7. Mitochondria present.|
|8. Lysosomes and Peroxisomes absent.||8. Lysosomes and Peroxisomes present.|
|9. Vacuoles absent.||9. Vacuoles present.|
|10. Microtubules absent.||10. Microtubules present.|
|11. Sexual reproduction is absent.||11. Sexual reproduction is present.|
|12. Examples: Bacteria and blue-green bacteria.||12. Examples: Plant cells and animals cells|
Functions of the cell:
A cell performs important functions that are essential for the growth and development of an organism. Important functions of the cell are the following:
It provides support and structure
All organisms are made up of cells. They form the structural basis of all organisms. The cell wall and cell membrane are the most important components that provide support and structure to the organism. The skin, for example, consists of a large number of cells. The xylem in vascular plants consists of cells that provide structural support to the plants.
Facilitating growth Mitosis
In the process of mitosis, the mother cell divides into daughter cells. In this way, the cells multiply and promote the growth of an organism.
Facilitates the transport of substances
Various nutrients are taken up by the cells to carry out various chemical processes in the cells. The waste products produced by the chemical processes are excreted from the cells by active and passive transport. Small molecules such as oxygen, carbon dioxide and ethanol diffuse through the cell membrane along the concentration gradient. This is referred to as passive transport. The larger molecules diffuse through the cell membrane by active transport, and the cells require a lot of energy to transport the substances.
Cells require energy to carry out various chemical processes. This energy is generated by the cells through a process called photosynthesis in plants and respiration in animals.
Helps in reproduction
A cell assists in reproduction through the processes of mitosis and meiosis. Mitosis is called asexual reproduction, in which the mother cell divides and forms daughter cells. Meiosis causes the daughter cells to become genetically different from the mother cell.
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