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Cells are the fundamental structural and functional unit of living beings. Two types of cellular organisms exist in nature:
- Unicellular
- Multicellular.
- G Loewy and P. Siekevit defined that cells were the basic unit of life in 1963. In 1665 Robert Hook observed that the cells’ structural pattern is like a honeycomb that contains a thick world and a box-like compartment, which he called a cell. A unicellular organism is a single cell organism, whereas multicellular organisms contain multiple cells.
Additionally, there are two types of cells: Prokaryotic cells and Eukaryotic cells. Some examples of a Eukaryotic cell include mitochondria, lysosomes, chloroplast, etc. Examples of prokaryotic cells include bacteria and cyanobacteria. The cell size is 1-2 * 1-4 µ or less, and in a Eukaryotic cell, the cell size is 5µ in diameter.
Various Characteristics of A Cell
The following are the various characteristics of a cell:
- Plasma membranes surround cells. Inside the cell, cytoplasm, DNA, and ribosomes are present which help maintain the cell body’s structure.
- The cell also helps to make the structure of DNA and RNA.
- A cell is the structural and functional unit of life.
- All cells arise from previously existing cells.
- All the cells are alive in chemical composition and metabolic activity.
- The structure and the support to an organism’s body is provided by the cell.
- The different organelle surrounded by the separation membrane are organised in the cell interior.
- The nucleus carries out the important genetic information for cell growth and reproduction.
- Cells contain only one nucleus and cell membrane bounded by the cytoplasm.
- Cells are responsible for making the organs of the body.
- Mitochondria, a double membrane organelle, is responsible for the transition of energy to make the cell survive.
- Lysosomes carry out the digestion of unwanted material.
- The endoplasmic reticulum plays a significant role in the internal organisation of the cell by synthesising selective molecules and processing, directing, and sorting them to their appropriate locations.
- The cell has to carry out nutrition, respiration, growth, self-regulation, reproduction, etc.
- It also helps in cellular organisation, reproduction, regulating stimuli, heredity and growth. It also helps in development adaptation through evolution, homeostasis, and metabolism.
Plant Cells | Animals Cells |
The cell wall is present in the plant cell | The cell wall is absent in the animal cell |
Plant cells are larger | Animal cells are smaller |
Plant cell cannot change its shape | Animal cell can change its shape |
Lysosomes are absent in plant cells | Lysosomes are present in animal cells |
Glyoxysomes are present in plant cells | Glyoxysomes are absent in animal cells |
Plastids are absent in plant cells. | Plastids are present in animal cells |
Plant cells contain a large vacuole with cells | Animal cell vacuoles are absent. If vacuoles are present, they are tiny in size. |
The shape of the plant cell is nucleus elliptical | The shape of the animal cell is rounded |
Some Important Terms related to Cells
- Cell wall- The cell wall is tough and rigid and helps determine the cell’s shape. It provides structural support to the cell and prevents it from bursting and collapsing. The cell wall is present in plant cells only.
- Plastids- Plastids are present in plant cells and absent in animal cells.
- Ribosomes- They are densely packed in chromosomes in RNA protein particles.
- Nucleoids are also known as nuclear materials present in the centre of the cell.
- Cytoplasm- Cytoplasm contains a Jelly-like protoplasmic food matrix, which is surrounded by the nucleus and constitutes the milieu of the cell.
Conclusion
All living organisms are made up of cells, which are the basic building components. There are trillions of cells in the human body. They support the body’s structure, absorb nutrients from meals, transform those nutrients to energy, and perform specialised functions.
