Prokaryotic cell
Prokaryotic cell:- Prokaryotic cell is that cell which lacks a well-defined nucleus and membrane-bound organelles.
For example: Bacteria,cyanobacteria,PPLO [Pleuro-pheumonia like organism] |
| Prokaryotic cell diagram |
1. Cell wall: cell wall in bacteria is made up of peptido-glycan which is a polymer of NAG & NAM.
NAG:- N-acetylglucosamine : NAM:- N-acethylmuramic acid
· It provide shape and rigidity to cell
2. Glycocalyx:- It is made up of polysccaride orprotein or both.
Function- It helps in the attachment of bacterial cell of various surfaces. In some bacteria,it also contribute to pathogenicity.[ Disease causing ability]
3. Flagella:- It is present in some bacteria. It is a locomotory structure that helps in the movement of bacteria. It is made up of protein called flagellin. Flagella is single standed in bacteria.
4. Plasma membrane: Plasma membrane is selectively permeable membrane present around cell
5. Mesosome: The are invagination or infolding of plasma membrane.
It has a role in DNA replication
It has a role in the formation cell septum for cell division.
Also help in repiration, secretion process and to increase the surface area of plasma membrane
6. Nucleoid: The naked DNA of prokaryotes which is not enclosed inside the nucleus is called nucleoid/ Genophore. In addition to genomic DNA, many bacteria have small circular DNA outside genomic DNA plasmids, which confers traits like antibiotic-resistance to bacteria.
7. Ribosomes: They are the protein factory of the cell. In prokaryotes ribosome lie freely in the cytoplasm and are of 70`S type, which have two subunits 50S & 30S.There are two types of ribosomes
1.70S ribosomes
2. 80S ribosomes
8. Thylakoid: They are present in some bacteria & blue-green algae which are autotrophic.They lie in cytoplasm and contain pigmets such as bacteria chlorophyll.
9. Protein granules & lipid globules: They lie freely in the cytoplasm.
10. Gas vacuoles: they are not true vacuoles & are present in some bacteria to provide buoyancy.
Example:- These gas are present in purple & green photosynthetic bacteria.
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