Prokaryotes - Introduction

Description:

Prokaryotic cells represent organisms like bacteria, mycoplasma, blue-green algae and PPLO (Pleuro Pneumonia Like Organisms). Prokaryotes are generally smaller and multiply more rapidly than the eukaryotic cells.

Prokaryotes do not have well defined nucleus and possess cell wall.

In addition to genomic DNA many bacteria have small circular double stranded DNA molecule not associated with the genomic DNA. These extra genomic DNA are called the plasmids. The plasmids provide additional advantages to these bacteria like resistance to antibiotics.

Membrane bound organelles are not found in prokaryotes like that present in eukaryotes except ribosomes.

Prokaryotes have certain infoldings of cell membrane called mesosome.

Shapes of the bacteria −

• Bacillus (rod like)
• Coccus (spherical)
• Vibrio (comma shaped)
• Spirillum (Spiral)