Are bacteria Prokaryotes or Eukaryotes?
Two types of cells that divides into Prokaryotic and Eukaryotic. A single unicellular organism is characterized as Bacteria and Archae. Bacteria and archae are classified as prokaryotes while animal cell plant cell, fungi, and protists are classified as eukaryotic organism. Prokaryotic cell contain plasma membrane, cytoplasm. The genetic material DNA and ribosomes. However, prokaryote are distinct from eukaryotes in many ways.
Prokaryotic cell is a unicellular organism that does not contain a definite nucleus and nuclear membrane. The DNA is localized in the central region of the cell called nucleoid.
The cell wall of bacteria is composed of peptidoglycan which is a mixture of sugar and amino acid. The cell wall functions for external protection, maintenance of cell wall shape, prevent the cell from dehydration.
The capsule present on bacteria allows it to attach to surrounding surfaces. Some prokaryotes also featured to contain flagella, Pilli. The flagella are used for movement while pili are used to exchange genetic material during conjugation.
A Eukaryotic cell contains a definite nucleus and its membrane bound nuclear membrane. They are usually multicellular organism containing several potential organelles which perform specialized functions. The term Eukaryotic means true nucleus and the word organelle means organs.
They are found in they are found in plants animals and protist. The cell size is 10-100 micrometers in diameter. The genetic material DNA is present inside a definite nucleus.
What exactly are bacteria-eukaryotes or prokaryotes?
The bacteria are among the well-known prokaryotes because they lack internal membrane and contain all the components of prokaryotes.
Characteristics of prokaryotic bacteria
Bacteria usually lack definite membrane bound nucleus and nuclear membrane and thus ranked among single-celled prokaryotes. Prokaryote exist as a dominant living creature on globe, nearly present for three quarters of Earth area and having the ability to adapt in almost all possible ecological habitats. At the group, they show broad range of metabolic capabilities and can process any e organic compound and some inorganic compounds as food and energy source. Some bacteria exhibit the nature of of disease causing organism in humans animals or plants however most of them are harmless and some of them prove to be beneficial ecological agents who metabolic activities sustain higher life forms.
Some bacteria also known to have a symbiotic Association with plants where the perform functions for the host such as nitrogen fixation and degradation of cellulose.
Prokaryotes are very important as they make soil fertile and slower the rate of decaying of organic material in the soil.
Bacteria as prokaryotes
All living organism existing on earth are made of two types of cells Eukaryotic and prokaryotic cells the Eukaryotic cells are doors in which the genetic material DNA is enclosed within a nuclear membrane while the prokaryotic cells are those in which from the rest of the cell. In earlier times all prokaryotic cells are called bacteria and were classified in the kingdom of prokaryotes named Monera.
However classification as Monera was similar in taxonomy to other kingdoms Such as Fungi, Plantae, and Animalia and Protists.
In the late 1970s, Carl Woese proposed the major changes in the classification by placing all the organism in three main domain that are Eukarya, bacteria and Archae to study the evolutionary aspect of organisms.
The domain of bacteria further divided into eubacteria (true bacteria) and archaea. They are superficially similar as they don't contain intracellular organelles they have a circular DNA but they are not logically distinct and the separation is different.
Thus, the members of two prokaryotic domains are different from one another as they are distinct from Eukaryotic cells
The prokaryotic cell
The prokaryotic cell are much simpler than the Eukaryotic cell as they lack intracellular organelles which is the key feature of Eukaryotic cell.
Organelles are discrete structure which are membrane bound localized in cytoplasm. As the prokaryotic cell does not contain specialized structures called organelles but all the activities performed by organelles also takes place in bacteria but they are not carried out by specialized structure.
In addition, the prokaryotic cell Are smaller in size with high metabolic capabilities that it enables them to grow and divide rapidly in every conditions.
Prokaryotic and Eukaryotic cell also differentiate in other ways like composition of lipid, enzymes involved, how the response to antibiotics and toxins, and the expression of genetic information. Eukaryotic organism contain many linear chromosomes with genes that and encode the synthesis of proteins.
In contrast, bacteria contain only one circular chromosome that contain all the genetic information needed for the molecular processes.
Most bacteria are surrounded by cell wall made composed of peptidoglycan layer.
The cell wall is meant for the protection and maintenance of cell shape many bacteria also have outermost layer of sugar call capsule. The capsule is sticky that makes it adherent to the surface environment. Bacteria also contains flagella structure which helps in locomotion.
In addition they also have fimbriae a hair like structure use for attachment to host cell. They also contain Pillai which helps in exchange of genetic information from one bacteria to another bacteria.
However, archae may also contain most of these cell features but they show typical difference in their cell composition to bacteria.
Glycosylation system in eukaryotes and prokaryotes
Protein glycosylation is a process common to all three domains of life forms. More than 70% of the Eukaryotic proteome is undergo the process of glycosylation. However, it is not full proven that precarious glycosylated, but it is clear that the prokaryotic glycoproteins are found in diverse range and the glycosylation occur in this organism.
Until now it was believed that the allocation process in the protein only occur in Eukaryotic organisms. However, in 1976 Mescher and Strominger reported that the protein from Halobacterium salinarum, an archeal prokaryote contain glycoproteins that were covalently associated with asparagine residues.
Over-the years, it is known that n glycosylation was more likely to in S layer of archae While the bacterial S layer seem to contain O- glycans.
Now in 21st century unexceptional research has found out that prokaryote especially Campylobacter jujeni showed the presence of N-glycosylation system. It is clear that the all three domains of life that is bacteria, archae, and eukarya contain N-Glycosylation system in it.
Why are Bacteria different from eukaryotes?
The major difference between eukaryotes and bacteria is that the presence of membrane bound definite nucleus in eukaryotes and absence of the same in bacteria. As science has all kinds of exceptions, one such bacteria named Gemmata obscuriglobus known to contain a double membrane enclosing the DNA in nucleus although the structure is contiguous plasma membrane. So in this sense bacteria 2 differ from eukaryotes and the above mentioned case is an exception.
The main function of having membrane bound nucleus is to perform transcription and translation which are not coupled. So there is a fundamental kinetics and organization is involved to distinguish eukaryotes and bacteria that the genetic material is coded in the form of protein and for further assembly cellular structure function and organization.
Another major difference between eukaryotes and bacteria is the proliferation of membrane bound organelles in eukaryotes such as Golgi, endoplasmic reticulum etc. again few bacterial species are exceptions that they contain membrane bound organelles which are contagious two plasma membrane. As these structures are in continuous state with plasma membrane they don't really separate physically in compartment.
In addition, Another evident differences the formation of multicellular organism in Eukaryotic cells like elephants and Redwood trees however bacteria call can also for multicellular structures like biofilm, require complex intercellular signaling, developmental system and extracellular matrix.
The largest community made by cyanobacteria called stromatolites these structures are made up of several layers that form through cycles of bacterial growth, deposition of matrix and mineral particle.
At last eukaryotes typically contain genomes that are larger in size and length that a normal size bacteria cannot process. Those genomes carry large number of non-coding DNA whose functions are not specified.