Explore the intricate Cell structure Prokaryotes and Eukaryotes. Discover their unique features and functions. Read now!
On the basis of status of nucleus, cells are of two types. The cell without true nucleus is called Prokaryotic cell. The cell with true nucleus is called Eukaryotic cell. Also Prokaryotic cell lacks membrane bound organelles. The eukaryotic cells possess membrane bound organelles. Both prokaryotic andeukaryotic cells have 70S ribosome common which is amembranous. Both prokaryotic and eukaryotic cell have cell membrane as universal structure.
Prokaryotic cell:
Prokaryotic cell is the primitive cell. It has simple structure and complex metabolism. Prokaryotic cell is the first cell that evolved.
Bacteria are the organisms with prokaryotic cell structure.All types of Bacteria including archaebacteria,Eubacteria are prokaryotes. Eubacteria are bacteria like cyanobacteria,photosynthetic bacteria, Heterotrophic bacteria and even mycoplasma are prokaryotic.
Prokaryotic cell structure:
The extra cellular outgrowths of prokaryotic cell are flagella,pilli and fimbrae. Flagellum is single fibre made of flagellin protein. Similarly, pilli and fimbrae are made of pillin protein. Pilli are tubular, hollow and help in conjugation between bacteria.Fimbrae help in attachment to surfaces and also to tissuees. Fimbrae are brush border like outgrowths.
Prokaryotic flagellum originates fron basal body which is the complex structure made of protein rings. Flagellum showsrotatory motion.
Then comes the unit envelope. It is made of outermost glycocalyx, cell wall and inner envelope called cell membrane. As you all know, the main function of envelope is protection.
capsule is thick, tough and gummy whereas slimelayer is loose and smooth. Also slime layer prevents loss of nutrient and water. Slime layer prevents drying.
Cell wall in Prokaryotic cell has rigid cell wall made of complex heteropolysachharide called Peptidoglycan or murein. Peptidoglycan is a heteropolymer of amino sugars such as N-AG and N-AM. Also murein has amino acids as tetrapeptide.
Cell membrane in prokaryotic cell is same as in Eukaryotic cell. Hence Cell membrane is universal structure.
The inner content of Prokaryotic cell is the cytoplasm, which has highly coiled circular double stranded DNA.
This naked DNA is called Nucleoid.
Cytoplasm has many ribosomes attached to m-RNA to form complex called Polyribosome or polysome.
Finally the entire prokaryotic cell metabolism and other cellular features are controlled by the naked double stranded DNA called as Nucleoid.
Other than the above living parts, prokaryotic cell also has nonliving amembranous reserve materials called as inclusions. The inclusions are cyanophycean granules,glycogen granules,volutin granules and gas vacuoles.
Eukaryotic Cell Structure:
These cells are with true nucleus and membrane bound organelles. The genetic material are called as chromatin materials.
Unlike Prokaryotic cell, the eukaryotic cell has double envelope system.
Cell wall if present is made of cellulose. Cytoplasm is the main arena of living activities. The cilia and flagella are made of microtubules with (9+2) arrangement. Also cilia and flagella are covered by cell membrane.
So, cell structure study shows a significant difference between prokaryotic and eukaryotic cell.
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