Question

What type of bacteria would have porins in their cell walls, and what extra layer do they have?

A. Gram-negative; Lipopolysaccharides
B. Gram-positive; Peptidoglycan
C. Both Gram-negative and Gram-positive; Peptidoglycan
D. Gram-negative; Peptidoglycan

Answer 1

Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane with porins and lipopolysaccharides, while Gram-positive bacteria have a thick peptidoglycan layer and lipoteichoic acids, and lack an outer membrane.

Step-by-step explanation:

Gram-negative bacteria are characterized by having a thin peptidoglycan layer surrounded by an outer membrane which contains lipopolysaccharides (LPS) and lipoproteins. An additional feature of the outer membrane of Gram-negative bacteria is the presence of porins, which are protein structures that allow the passage of molecules into and out of the cell. In contrast, Gram-positive bacteria have a thick peptidoglycan layer and do not possess an outer membrane like Gram-negative bacteria. Instead, Gram-positive bacteria have teichoic acids, including lipoteichoic acids that anchor the cell wall to the cell membrane. The different structural components are the reason for the varying responses to Gram staining, which is a method used to differentiate these two major groups of bacteria.