Prokaryotic and Eukaryotic Cells | World Today

                                               Prokaryotic and Eukaryotic Cells 

All living organisms present on earth can be classified into two following types:

1. Non-cellular Organisms that do not contain any cell in their body organisation, e.g., viruses. Viruses lack any membrane and hence do not show characterstics of life until they enter a living body (i.e., prokaryotic cell or eukaryotic cell) to use its cell machinery to reproduce.

2- Cellular Organisms that contain either one or many cells in their bodies, e.g., bacteria plants an animals.

Cellular organisms are again divided into following two main types :

(a) Prokaryotes. These organisms have primitive ad incomplete cells. Thus hey contain prokaryotic cells in their body structure. Prokaryotic cells have all three basic structures of a typical cell but lack nucleus membranes around their genetic substances (DNA).

Nuclear material of prokaryotic cell consists of a single chromosome which is in direct contact with cytoplasm. Here the undefined  nuclear region plas in the cytoplasm is called nucleoid, there is no nuclear membrane. In a prokaryotic cell other membrane bound organelles  such as mitochondria are also absent. Ribosome however are present in prokaryotic cell the prokaryotes include archive bacteria bacteria and cyanobacteria which earlier called blue green algae 

(b) Eukaryotes. These have advance send complete sales These cells contain membrane found nuclear and other cellular organism and are called eukaryotic cell such cell or found in unicellular and multicellular plant and animal and contain plasma membrane nucleus DNA and cytoplasm with I was home and cellular organism is mitochondria.

The differences between prokaryotic cell and eukaryotic cell are given in table.

                                                       Prokaryotic cell.

1- Size of a cell is generally small (1-10 mm)

2- Nucleus is absent (nuclear region or nucleoid is not surrounded by a nuclear membrane) . 

3-It contains single chromosome.

4- Nucleolus is absent.

5- Membrane bound cell  organelle absent.

6- Cell division take place by fission or budding (no mitosis).

                                                     Eukaryotic cell.

1- Size of a cell is generally large (5-100 mm).

2- Nucleus is present ( Nuclear material is surrounded by a nuclear membrane ).

3- It contains more than one chromosome.

4- Nucleolus is absent.

5- Membrane bound cell organelle such a s mitochondria, plastids, endoplasmic reticulum, Golgi apparatus, lysosomes, Peroxisomes, etc., are present.

6- Cell division occurs by mitotic or meiotic cell division.