KINGDOM-MONERA (prokaryotes)
Main characteristic of prokaryotes
1. Glycocalyx (Capsule or Slime layer) - —Loose and thin layer is called slime layer and thick and tough layer is called capsule. Formation of Glycocalyx is done
by cell membrane. —Capsule is made up of polysaccharides and polypeptides while slime layer is made up of mainly polysaccharides.
—Glycocalyx protects the bacteria from W.B.C. and also helps in colony formation
2. Cell wallCell wall of prokaryotes is made up of peptidoglycan (peptide(amino acid) + glycan(polysaccharide)).
3.Cell membrane—Like eukaryotes the cell membrane of prokaryotes is made up of lipoprotein [lipid + protein].—The cell membrane invaginate and form structure like mesosomes and chromatophores that perform function like respiration and photosynthesis respectively.
—The space between cell wall and cell membrane is known as periplasmic space.This space, is analogous to lysosome because in this space the digestion of complex substance is done.
4.Cytoplasm— In bacterial cytoplasm membrane bound cell organelles viz. Mitochondria, Chloroplast, E.R., Lysosome, Golgi body, micro bodies etc. are absent.—Bacterial cytoplasm shows no streaming or cyclosis.
(A). Storage granules/Inclusion bodies -—Reserve material in prokaryotic cells are stored in the cytoplasm in the form of inclusion bodies.—These are not bounded by any membrane system and lie free in the cytoplasm.
(B). RIBOSOMES- membrane less cell organelle.—only organelle founds in both prokaryotic and eukaryotic cell.—ribosomes perform function of protein synthesis— in prokaryotes 70s type of ribosomes are found
(C). Gas vacuoles - membrane less structure that provide buoyancy.
(D).Nucleoid- In Prokaryotic cell, the nucleus is indistinct. The nucleus of prokaryotes is also known as incipient nucleus, genophore, nucleoid or fibrillar nucleus. —Nuclear membrane is absent around nucleus. —It also lacks nucleolus.—Prokaryotes also lack the true chromosome. Instead of it, a false
chromosome is present, which is made up of ds circular naked DNA + Non histone protein like polyamines.—This false chromosome coils and forms the chromosomal region, which is known as nucleoid.
(E).Plasmid - Beside the main DNA another small and ds-circular DNA is also present in bacterial cell, which is called Plasmid.—It is also known as extra chromosomal or extranuclear genetic material.
5. Flagella- flagella is a modification of cell wall.— it help in motility6. Pili- Bacterial cell wall is covered by numerous hair like structures called pili. Pili are smaller than the flagella. — pili play role in attachment
Prokaryotes Eukaryote Simple cell Complex cell
primitive cell Advanced cell
Smaller cell Larger cell
Always found in unicellular organisms
Found in both unicellular and multicellular organisms
Nuclear membrane absent
Present
Nucleolus absent Present
Double stranded circular DNA found
Double stranded linear DNA found
Histone protein absent
Present
True chromosome absent
Present
True nucleus absentNucleoid/xenophobia/ incipient nucleus found
True nucleus present
Glycoclayx present Absent
Cell wall is made up of peptidoglycan
Peptidoglycan absent
Cholesterol absent in cell membrane
Present
Mesosomes present Mitochondria present
Chromatophores present
Chloroplast present
70s ribosomes present 70s and 80s ribosomes present
Inclusion bodies present
Absent
Gas vacuoles present
Absent
Plasmid present Absent
Cytoplasmic movement’s absent
Present
Prokaryotes Eukaryote
Examples of Prokaryotes(1) Eubacteria (True bacteria)(2) Mycoplasma(3) blue green Algae(4) Archaebacteria
Pili present Absent
Sexual reproduction absent
Present
Mitosis meiosis absent
Present
Prokaryotes Eukaryote