PROKARYOTES V/S EUKARYOTES (prokaryotic and eukaryotic organisms)

PROKARYOTES AND EUKARYOTES

Microorganisms are broadly classified in to two group viz. cellular and acellular.

Acellular organism:- Acellular means 'cell free’ The micro-organism that have neither cells nor cell membrane. They are composed of few genes which are protected by protein coat. They are alive and reproduce only inside host outside of the host they acts as dead.

Cellular organism:- The micro-organism which have definite cell structure is known as cellular organism. Cellular organism are divided in to two group

1. Unicellular

2. multicellular.

Unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell.

Multicellular organism is an organism that consists of multiple cells.

Cellular organisms also divided in to two general categories: prokaryotic organisms and eukaryotic organisms.

Prokaryotes and Eukaryotes Definition:-

Prokaryotes definition:- Prokaryotes is derived from two Greek words “Pro” means before And “Karyon” means nut or kernel referring to the cell nucleolus. So prokaryotes means before nucleus.

Prokaryotic cells are the simple and most primitive cells. They do not have definite nucleus and membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi complex, lysosomes, & centrioles etc. This means the genetic material DNA & RNA in prokaryotes is not bound within a nucleus. They do not remain isolated or separated from the cytoplasm. Prokaryotic chromosomes are found in localized area of the cell called the nucleoid region.

In addition, the DNA is less structured in prokaryotes than in eukaryotes. In prokaryotes, DNA is a single loop while in Eukaryotes DNA is organized into chromosomes. Most prokaryotes are made up of just a single cell (unicellular) but there are a few that are made of more than one cells (multicellular). In prokaryotes asexual division occurs, basically binary fission.

Examples of prokaryotes: - Bacteria, and the Archaea.

Components of Prokaryotic Cells

Prokaryotic cell diagram

1. Cell wall: the membrane surrounding and protecting the cell

Plasma membrane, an outer covering that separates the cell’s interior from its surrounding environment.
Cytoplasm, consisting of a jelly-like region within the cell in which other cellular materials are found;
DNA, the genetic material of the cell;
Nucleoid: a nucleus-like region of the cell where genetic material is kept
Flagella and pili: protein-based filaments found on the outside of some prokaryotic cells which is responsible for motility.
Plasmid: a small molecule of DNA that can reproduce independently
Ribosomes, particles that synthesize proteins

Eukaryotes definition:- Eukaryotes is derived from two Greek words “Eu” means good or true and “Karyons” means nut or kernel referring to the cell nucleus. So eukaryotes means true nucleus.

Eukaryotes are organisms made up of cells that possess a membrane-bound and clearly defined nucleus (that holds DNA in the form of chromosomes) as well as membrane-bound organelles such as mitochondria, endoplasmic reticulum, golgi complex, lysosomes, centrioles etc.Eukaryotic organisms may be multicellular or single-celled organisms.

E.g. All animals are eukaryotes. Other eukaryotes include plants, fungi, and protists.

Components of Eukaryotes:-

Eukaryotic cell diagram

1. Eukaryotic cells have a “true” nucleus, membrane-bound organelles, and rod-shaped chromosomes.

2. Cytoplasmic membrane: - protects the cell from its environment.

3. Endoplasmic reticulum: - modifies proteins and synthesizes lipids.

4. Ribosomes:- help in protein synthesis.

5. Nnucleus: - consist of nucleolus, chromosomes surrounded by nuclear membrane that houses the cell’s DNA and directs the synthesis of proteins and ribosomes.

6. Golgi apparatus: - Where the sorting of lipids and proteins takes place.

7. Mitochondria:- Responsible for ATP production.

8. Cytoplasm: -It is the gel-like, water-based fluid that occupies the majority of the volume of the cell. Its functions as the site of energy production, storage, and the manufacture of cellular components.

Prokaryotes Vs. Eukaryotes: What Are the Differences?

Prokaryotes and eukaryotes differences (Comparing the Two Basic Types of Cells)

CHARACTER	PROKARYOTES	EUKARYOTES
Cell type	Usually unicellular some cynobacteria may be multicelluar	Usually multicellular
Size	0.1- 5.0 um	5-100 um
Nucleus	Absent	Present
Nuclear membrane	Absent	Present
Nucleolus	Absent	Present
Chromosome	Single (circular)	More than one (linear)
Mitotic division	Absent	Present
Deoxyribonucleoproein	Absent	Present
Cytoplasmic straming	Absent	Present
Mitochondria	Absent	Present
Golgi apparatus	Absent	Present
Endoplasmic reticulum	Absent	Present
Lysosomes	Absent	Present
Chloroplast	Absent	May be Present
Pinocytosis	Absent	Present
Ribosomes	70s distributed in the cytoplasm	80s arrayed one membranes as in endoplasmic reticulum, 70s in mitochondria and chloroplast.
Microtubule	Absent	Present
Vesicles	Present	Present
Gas vacuoles	Can be present	Absent
Mesosomes	Present	Absent
Cytoplasmic membranes	Generally sterols absent	Generally sterols present
Cell wall	Peptidoglycan present	Peptidoglycan absent
Locomotor organells	Simple fibril	Multifibrilled with g + z microtubules
Pseudopodia	Absent	Present in some
Examples	Bacteria, Archaea, Actinomycetes, Chalmydiae, Rickettsiea	Plants, Animals, algae, Fungi, Protozoa,