Cell Structure

All the living organisms that exist in this universe – like mushrooms, plants, humans, elephants etc. are all composed up of a basic unit called the cell.

The cell is the structural and functional component of life. Every living creature is composed single cell or many cells. Therefore it is referred to as the fundamental unit of life. The size of each cell ranges from millimeter to microns and generally, their shape varies from flat, rod, oval, spherical, curved, concave, rectangular, etc.
The term cell was observed, identified and coined in the year 1665 by an English physicist Robert Hook.

Let us explore more about the Cell Structure along with their functions.

 

Cell-Structure

 

There are numerous cells present in organisms, which are involved with several functions throughout the life. The different types of cells varying in their size, shape and the number of cells such as – unicellular, multicellular, prokaryotic and eukaryotic cell. The size and the shape of the cell range from millimeter to the microns and are generally based on the type of function that it performs. The cell generally varies in their shapes including concave, curved, flat, oval, rectangular, spherical, rod-shaped, etc. which can only be seen under the microscope.

Are cells essential for a life?
Yes, cells are essential for a life. Each and every living organisms on earth require cell, as it plays a primary role in guarding and keeping us alive by controlling different types of biochemical functions within an organism. A new cell is produced through cell division of pre-existing cells.

Different Types of Cells

Types of cells: – The cells are classified into two – prokaryotic cell and eukaryotic cell based on the presence or absence of true nucleus in the cell.

Types of Cells

A typical cell contains cytoplasm which is bounded by a thin layer membrane known as the cell membrane. The main function of a cell membrane is to protect the components of the cell from the external environment. Selective substances are only allowed to enter the cell through the cell membrane. It consists of other cell organelles like mitochondria, nucleus etc.

Cells are combined together to form tissues and eventually tissues form organs and then organs form organ systems such as digestive system, circulatory system, central nervous system, etc. They aggregate together to form different forms of life in different shapes and sizes. Some of the organisms are multi-cellular like humans whereas others are unicellular like bacteria and protozoa. There is a special function of the cell in which they can replicate themselves.

Cell Structure and Their Functions

Cell organelles Functions
Cell wall Provide support, shape and protects the internal organelles of cells.
Cell membrane (or) Plasma membrane Controls the secretion of proteins and elimination of waste products.
Cytoplasm They are the site of cellular activities.
 Nucleus The storehouse of the cell’s genetic materials. It plays a primary role in reproduction and guides the activity of a cell.
Nucleolus It is the site of manufacturing cell’s ribosomes, involved in controlling cellular activities and cellular reproduction.
Nuclear membrane Protects nucleus by forming a boundary in between the nucleus and other cell organelles.
Chromosomes They play an important role in determining a sex of an individual.Each human cells contain 23 pairs of chromosomes.
Endoplasmic reticulum Involved in the transportation of substances throughout the cell. It plays a primary role in the metabolism of carbohydrates, synthesis of lipids, steroids, and proteins.
Golgi Bodies It is called as the cell’s post office as it is involved in the transportation of materials within the cell.
Ribosome They are the protein synthesizers of the cell.
Mitochondria It is called as the cell’s powerhouse as it is involved in producing and transforming the energy (ATP).
Lysosomes  It protects the cell by engulfing the foreign bodies entering the cell and helps in cell renewal. Therefore, it is the cell’s suicidal bags.
Chloroplast They are mainly involved in photosynthesis. As it contains the green colored pigment called chlorophyll.
Vacuoles Stores food, water, and other waste materials.

Interesting facts about the cells.

  1. There are more nerve cells present in the brain than the stars in a milky way.
  2. Joining together the blood cells of the blood vessels can form a path that will be about hundred thousand kilometers long and can circle the earth twice.
  3. Moving towards DNA, the heredity part of our body, if we join the DNA present in the nucleus of all the cells of a human body then we can measure the distance between earth and the sun around 600 times.
  4. These cells are very small and cannot be seen by our naked eyes. They can be seen only through some special equipment such as a microscope. The microscope was discovered during the 17th century.

Stay tuned with BYJU’S to learn more about the cell, its structure, and its functions with interactive video lessons.


Practise This Question

Structures present in the cell which carry out specific functions are called___________.