Overview Of Cell Biology

A cell is the structural and fundamental smallest unit of life or living organisms. The branch of science that deals with the study of cells are called cell biology.

Organization Of Cells

The cell was first observed by Robert Hooke in 1665. They observed cell thin slices of cork. He observed from the cavities of the hollow space of cork and used the term cell. The term cell is achieved from the Latin word “cella” which means hollow space. Anton Van Leeuwenhoek was the first to notice living cells in microorganisms.  

Types of Cells

Based on Structure, cells are two types.

• Eukaryotic Cells
• Prokaryotic Cells

Eukaryotic Cells

The nucleus is found in eukaryotic cells and the development of organisms is complete. Eukaryotic cells consist of the membrane-bound organelle. The cell organelles and nucleus are contained in the cytoplasm. A eukaryotic cell is covered by a plasma membrane. The inner side of their nucleus is rod-shaped chromosomes that are covered by a nuclear membrane. 

They can support different environments in the same cell which allows them to carry out different metabolic reactions.  these cells help them to grow many times larger than the prokaryotic cells.

Example- Animal Cell, Plant Cell

Prokaryotic Cells:-

The prokaryotic cell does not present a nucleus and the organism is not in complete development it is called a Premature or Primary cell. A prokaryotic cell contains a single membrane and therefore, all actions and reactions occur within the cytoplasm.  These cells can be free-living or parasites.

Example – Bacteria and Virus

Performs Difference Between The Eukaryotic Cell And Prokaryotic Cella are-

Feature	Prokaryotic Cell	Eukaryotic Cell
Plasma Membrane or Cell Wall	Plasma membrane present and cell wall absent	Plasma membrane present  but cell wall present in plant cell
Cytoplasm	Cytoplasm doesn’t show streaming movement	Cytoplasm show streaming movement
Endoplasmic Reticulum	It is absent in prokaryotic cell	It is present and perform a critical role in cellular transport
Ribosome	70 S ribosome are present it is randomly scattered in the cytoplasm	80 S ribosome are present it is attached to the rough endoplasmic reticulum
Mitochondria	It is absent	It is present and It is called as power of energy
Respiratory Enzyme	They are located on the plasma membrane	They are on closed in mitochondria
Chromosomes	Only the following histone proteins are present in a single circular structure made of DNA.	DNA is present more than histone protein
Flagella	Present in some species of bacteria but do not have 9+2 arrangement	It is present in some species of eukaryotic cell but with 9+2 arrangement
Cell Division	These cells is divided by the simple fission method no meiosis and mitosis method	Cell division by mitosis and meiosis

The Cell Theory 

The cell theory was purposed by T. Schwann in the year 1839. These theories are three parts. The first part of cell theory states that all organisms are made of cells. The second part of cell theory states that cells are the basic units of life. These parts were based on a conclusion made by  T. Schwann and M. Schleiden in 1838, after differing their observations of plant and animal cells. The third part  is, which asserts that cells come from preexisting cells that have multiplied, was described by Rudolf Virchow in the year1858,

The essential characteristic of a cellular idea is

• Cells are the fundamental unit of structure and function in all living organisms.
• Cells are the metabolic and physiological unit of a living organism. 
• Cells are a hereditary unit.
• A new cell organizer from an already existing cell unit.
• Cells are the smallest unit of lifestyle. 

Cell Diversity

Cells of different organisms and even cells within the same organism are very diverse in terms of shape, size and internal organization. There are at least 200 different cell types, from flat cells to branching cells to round cells to rectangular cells.. 

Cell Shape

•  Variation in cell shape reflects different functions of cells
  

Cell Size

• Cells are different in their size  as well as  their shape 
• Most cells are about 1/500th size of the period at the end of a sentence.
• The size of a cell is limited by the relation of the cell’s outer surface to the volume surface to volume ratio
  

The basic part of the Cell

There is three basic part of the cell Plasma Membrane, Cytoplasm, and nucleus.

Plasma Membrane

Plasma Membrane is a thick floor membrane in a cellular. which isolates cell cytoplasm from the external medium and helps in maintaining in term of composition and regulating the entrance and go out of molecules and ions in and out of the cell. it was the first time observed by Ernest Overton in the year 1899 in the plant cell.

Cytoplasm

The area of ​​the cell that lies within the plasma membrane and includes the fluid, cytoskeleton, and all the organelles The cytosol is the part of the cytoplasm that includes molecules and small particles but is not a membrane-bound organelle

Nucleus 

 The nucleus was firstly discovered by Robert Brown in 1881. It is called the controlling centre of the cell because it controls all the cellular activity since it contains chromosomes and genes. A well-organized nuclear with ratio nuclear membrane absent on bacteria virus & blue-green algae on the basis of tense & absence at well define nuclear a living organism.