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Cell | What is cell | Cell theory

 Definition Of cell

A cell is a structural and functional unit of life, which carries all activities of life.

Cells are the main building blocks of complex multicellular organisms.

Different cells perform different functions, an organism is the combined sum of activities and interactions of many kinds of cells and of different components of the cell. Modern cell theory is 

Cell Theory Features;

All organisms comprise one or more cells.

All cells arise from preexisting cells.

A cell is a structural and functional unit for all organisms.

What are Types of cells

There are two types of cells are in nature. which are

Prokaryotic cells

Eukaryotic cells 

Prokaryotic cells

Typical Prokaryotes (Greek : pro – before; karyon nucleus)  don't have defined nucleus and contain relatively simple structure.They include the bacteria and cyanobacteria. Most detailed studied prokaryotic cell is Escherichia coli. Organisms containing prokaryotic cells called prokaryotes.


Characteristics of prokaryotic cells

It is small in size and has a minimum of internal organization.

Membrane bound organelles are not present in prokaryotic cells and have small size ribosomes 70S.

 Mitosis or meiosis are not present so the cell is divided by binary fission.

The genetic material of prokaryotic cells is without any nuclear membrane covering and directly suspended in cytoplasm.

Eukaryotic cells 

2. Eukaryotes (Greek : eu – true; karyon 

nucleus) contain a well defined nucleus and are complex in their structure and function.

The higher organisms (animals and plants) including humans are composed of eukaryotic cells.

Organisms containing eukaryotic cells called eukaryotes.

 Characteristics of eukaryotic cells.

Eukaryotic Cells are larger in size and have large ribosomes 80S.

Eukaryotes have a nucleus so nuclear materials ( chromosomes or DNA) are enclosed in a double nuclear membrane.

Mitosis and meiosis both are present in eukaryotes.



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