Mesosomes
மீசோசோம்கள்
Do not confuse Mesosomes with Mitochondria. Prokaryotes lack membrane-bound organelles, yet they perform respiration. Mesosomes are the structural solution to this evolutionary constraint.
The idea
Mesosomes are specialized differentiated forms of the prokaryotic cell membrane. They are formed by the infoldings of the plasma membrane into the cell. These structures facilitate respiration, secretion processes, and increase the surface area of the plasma membrane. They also play a critical role in enzymatic content distribution and DNA replication.
Why it matters
Since prokaryotes lack mitochondria, mesosomes provide the necessary surface area for metabolic and enzymatic activities.
NEET lens
NEET focuses on the origin and function of mesosomes. Remember: they are infoldings of the plasma membrane, not independent organelles. Expect 'Match the Following' questions linking mesosomes to DNA replication or respiration. Do not mark them as present in Eukaryotes.
Clinical significance
Mesosomes are the functional equivalent of mitochondria in bacteria. If these structures fail, bacterial ATP production ceases, effectively killing the pathogen. Modern antibiotics often target the integrity of the bacterial cell membrane to disrupt these vital respiratory sites.
Introduction
Mesosomes are irregular infoldings of the plasma membrane in prokaryotes, associated with cell wall synthesis, DNA replication, and possibly respiration.
Core concept
Structure: invaginations (inward folds) of plasma membrane forming vesicles, tubules, or lamellae. Functions proposed: cell wall synthesis during division, DNA attachment and replication, secretion of extracellular enzymes, respiratory functions (substitute for mitochondria). Found only in prokaryotes.
Go deeper
Mesosomes are controversial — some researchers believe they are artifacts of chemical fixation during electron microscopy, not real structures. However, NCERT treats them as real structures, so for NEET, they are real.
From Class 10
Bacteria are simple cells but they have internal structures too. Mesosomes are one such structure unique to bacteria.