Prokaryotic Cells

• Prokaryotes are single-celled organisms.(0.1-10 µm long).
• Prokaryotic cells are much smaller than eukaryotic cells.
• Prokaryotic cells have:

  • Cytoplasm without any membrane bound organelles
  • Smaller, 70S ribosomes
  • No nucleus
• Prokaryotic cells have a circular loop of DNA free in the cytoplasm which is not associated with any histone proteins.
• The cell wall of prokaryotic cells is made of murein (peptidoglycan).
• • Prokaryotes have no distinct nucleus, only an area where DNA is found.
  • Eukaryotes have a distinct nucleus with a nuclear envelope/ membrane.
• • DNA in prokaryotes is not associated with histone proteins.
  • DNA in eukaryotes is associated with histone proteins.
• • Prokaryotes contain circular DNA.
  • Eukaryotes contain linear DNA.
• • Additional circular plasmids may be present in prokaryotes.
  • Plasmids are not present in eukaryotes.
• • There are no membrane bound organelles in prokaryotes.
  • There are membrane bound organelles such as the nucleus and mitochondria in eukaryotes.
• • The ribosomes in prokaryotes are smaller (70S).
  • The ribosomes in eukaryotes are larger (80S).
• • The cell wall in prokaryotes is made up of peptidoglycan.
  • The cell wall in plants is made of cellulose.
  • In fungi, it is made of chitin.
• • Prokaryotes may have an outer capsule.
  • There is no capsule present in eukaryotes.
• Some prokaryotes have an outer slime capsule. This is a polysaccharide layer which prevents detection in the host body and desiccation (dehydration/ drying out).
• Prokaryotes contain a nucleoid (long looped DNA containing most of the genetic material). It is not associated with histone proteins.
• Some prokaryotes have one or more flagella. These are made out of protein and are responsible for locomotion.
• The 70S ribosomes are made of ribosomal RNA and protein.
• The surface cell membrane allows the passage of materials into and out of the cell.
• The peptidoglycan cell wall provides the cell with structure and protection.
• The plasmids can be transferred from one bacteria to another and sometimes contain genes for antibiotic resistance.