Cell : The Unit of Life
Structure of prokaryotic cell
- Prokaryotic cells are small in size (1-10μm).
- They are unicellular organisms eg. bacteria, blue green algae, mycoplasma and PPLO (pleuro pnemonia like organism)
- All prokaryotes have a cell wall (composed of peptidoglycans) surrounding the cell membrane. It also contains the fluid filled matrix named cytoplasm.
- The main difference between prokaryote and eukaryote is that, the genetic material present in prokaryotes is naked circular DNA, not enclosed by nuclear envelope.
- Many bacteria have small circular DNA along with genomic DNA
- On the plasma membrane, some circular coiled bodies called mesosomes are present which contain respiratory enzymes like oxidases and dehydrogenase and help in respiration.
- The cell envelope consist of tightly bound three layered structure i.e, the outermost glycocalyx followed by the cell wall and the cell membrane.
- Gram positive bacteria (eg: streptococcus, staphylococcus, Bacillus, Mycobacterium, streptomyces etc) respond to gram staining, others that do not are called gram negative (eg: salmonella, pseudomonas, E.Coli, Rhizobium, Helicobacter etc).
- The plasma membrane present in prokaryotes are similar to that of eukaryotes which is semipermeable in nature and interact with outersurface.
- Bacterial cells may be motile or non motile. Motile bacteria has flagella which is composed of three parts- filament, hook and basal body.
- The cytoplasm present in prokaryotes is granular due to the presence of large number of ribosomes (70s).
- Reserve material stoned in the form of inclusion bodies which is present in cytoplasm. (Eg:- Phosphate granules, glycogen granules).
- Cell division of prokaryotes are mostly amirotic.
- To remember gram -Ve & gram +Ve bacteria → LONG PPT
L - Lipopolysaccharide P - Positive
O - Outermembrane P - peptidoglycan (Thick)
N - Negative T - Teichoic acid
View this video for the topic from 8:52 to 27:53
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