Prokaryotic Cell Structure, Biology tutorial


Prokaryotic cells are as well termed as prokaryotes. They are a kind of biological cell which don't encompass a cell nucleus or any membrane-bound organelles like mitochondria. That is, neither the DNA of prokaryotic cells nor any of the sites of the metabolic activity in a prokaryotic cell are collected altogether in a discrete membrane-enclosed region. Rather, the whole thing is openly accessible in the cell example: ribosome are scattered all through the cytoplasm (not joined to the surfaces of the endoplasmic reticulum as in the animal cells). Illustrations of prokaryotic cells comprise the cells of many bacteria, example: vibrio cholerae, the cholera bacterium.

Details of Prokaryotic Cellular Components:

A prokaryotic cell is much simpler and smaller than the eukaryotic cells. It is deficient in membrane bound organelles comprising nucleus. The explanation of prokaryotic cells components are as follows:

1) Prokaryotic Cell Wall:

Prokaryotic cells are bounded by a cell wall that provides support and protection to the cell.  It is build up of polysaccharides termed as peptidoglycans that are branched molecules of peptides and sugars. The cell wall is extremely strong and stops bacteria from bursting whenever they absorb water. It as well protects them from viruses. Antibiotics like penicillin work by damaging the cell wall and thus killing the bacteria.

Most of the bacteria have a thick layer of jelly-like material surrounding them termed as a capsule that protects it from attack by antibodies and viruses.

2) Prokaryotic Cytoplasmic Membrane:

The prokaryotic cell membrane consists of a similar structure to the eukaryotic cell membrane, however it doesn't have cholesterol. Photosynthetic bacteria contain invaginations of the membrane which project within the cell and hold the molecules that are concerned in capturing light energy. Bacterial cytoplasm is water based fluid having ribosome, nutrients, enzymes, ions, waste products and storage granules. 

3) Nuclear Material:

In disparity to eukaryotic cells, bacterial cells have neither a distinct membrane-enclosed nucleus nor a mitotic apparatus. Though, they do include a region near the centre of the cell which is regarded as a nuclear structure and the DNA of the cell is confined to this region.

4) Cytosol:

The cell membrane surrounds the cytoplasm termed as Cytosol. The Cytosol enclosed by the cytoplasmic membrane might be classified into: (i) cytoplasmic region, granular in appearance and rich in the macromolecular RNA-protein bodies termed as ribosome, on which proteins are synthesized; (ii) the chromatin area, rich in DNA; and (iii) the fluid part having dissolved substances. Dissimilar animal and plants cells, there is no endoplasmic reticulum to which ribosome are bound.

5) Ribosomes:

Ribosomes are the site of protein synthesis. Bacterial Ribosomes are identical to eukaryotic Ribosomes, however they are smaller.

6) Flagella:

Flagella are employed for movement. They are long projections which rotate similar to propellers, pushing the bacteria along.  Comprise of microtubules arranged in a circle of nine pairs surrounding a central pair which is made up of protein.

7) Bacterial chromosomes:

The DNA of bacteria is a single, big and circular molecule. Prokaryotic DNA doesn't form chromosomes, and doesn't encompass histone proteins related with it. It lies free in the cytoplasm as there is no nuclear envelope in the prokaryotes.

8) Plasmids:

Bacteria might as well have small rings of DNA termed as plasmids and also the bacterial chromosome.  Plasmids frequently carry genes for features like antibiotic resistance and they can be passed from one bacterium to the other.  Plasmids are frequently employed in genetic engineering, for transferring genes from one cell to the other.

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