Question

Porins are present in ______________bacteria because, in these organisms, molecules entering the cell must pass through an extra layer of ___________.

a) Gram-positive; peptidoglycan
b) Gram-negative; lipopolysaccharide
c) Archaeal; pseudomurein
d) Spirochetal; outer membrane

Answer 1

Porins are proteins in the outer membrane of Gram-negative bacteria that allow the passage of substances, necessary due to the extra lipopolysaccharide layer.

Step-by-step explanation:

Porins are crucial components in Gram-negative bacteria's outer membrane, which is characterized by its distinct structure, including a thin peptidoglycan wall and an outer membrane rich in lipopolysaccharides (LPS) and lipoproteins. The presence of this extra layer of LPS makes the outer membrane impermeable to many molecules. Porins, specialized proteins embedded in the outer membrane, function as channels, facilitating the passage of ions and small molecules through the membrane. These channels play a pivotal role in nutrient uptake and waste elimination, contributing to the adaptability and survival of Gram-negative bacteria in diverse environments.