Question

Microbiology question, please explain in your own words!!!

The plasma membrane is selectively permeable. This means that it allows some substances to enter and leave a normal healthy cell, unrestricted. Toxins produced by certain bacteria cross the plasma membrane, interfering with normal chemical reactions, and ultimately killing the affected cell. In your own words explain why are cells unable to stop the flood of harmful substances such as botulin into the cell?

Answer 1

Answer: Plasma membrane is the barrier present around the cells to prevent the free movement of substances from external environment to inside the cell or vice versa. The permeability of substance inside the cells by different means: simple diffusion, passive diffusion, active diffusion, different types of endocytosis (phagocytosis, pinocytosis and receptor mediated endocytosis). The toxins produced by the organisms not diffuse inside the cells freely. The produced toxin binds with the receptor present on cell surface that leads to receptor mediated endocytosis and then interfere the normal physiological functions of host cells that ultimately leads to death of cell or organism. Botulinum toxin is a neurotoxin produced by Closterium botulinum that prevents the neurotransmitter acetylcholine at the neuromuscular junctions cause the paralysis. Botulinum toxin (Botulin) binds with Hc receptors present on the cell surface then receptor mediated endocytosis takes place inhibit the acetylcholine effect.