Question

Porin-like structures are prevalent among Gram-negative bacteria. Why are these structures stable in the membrane? (Hint: Compared alpha helix and beta strand. Explain genetic economy.)

Answer 1

Porin like structure are prevalent among Gram negative bacteria.Porin are composed of Beta strand which are linked by beta turns on there cytoplasmic sides. The beta strands liye in an antiparallel fasion and form a cylindrical beta barrel sheet.The beta barrel that make up the porin are made of about 8 to 20 beta strands.

In gram negative bacteria the inner membrane is a major permeability barrier.Due to the presence of the porin the outer membrane is permeable to hydrophilic substance.

Porins are usually found on the eukaryotic organism specifically in the outer membrane of chloroplasts and mitochondria.This all has been due to the endosymbiont theory, through which eukaryotic organelles arose from gram negative bacterias.