Question

Gram (−)ve bacteria possess peptidoglycan and an extra layer of
(A) Protein
(B) Lipoprotein
(C) Lipopolysaccharide
(D) Lipid

Answer 1

Hint: Gram (−)ve bacteria also possess an extra layer which is also known as endotoxins and are large molecules and consist of lipid A, oligosaccharide, and O antigen. It also protects the bacteria from the various chemical attacks it comes across.

Complete answer:
Lipopolysaccharide (LPS)is also known as endotoxins. LPS is an additional layer that is present in gram-negative bacteria. Peptidoglycan is common in both bacteria i.e gram-positive and gram-negative.

Additional Information: Gram-negative bacteria are bacteria that do not retain the gentian violet stain utilized within the Gram staining method of bacterial differentiation. Gram-negative bacteria are characterized by their cell envelopes, which are composed of only a few layered peptidoglycan cell walls which are present between an inner cytoplasmic cell membrane and a bacterial outer membrane. Gram-negative bacteria are a crucial medical challenge, as their outer membrane protects them from many antibiotics (including penicillin); detergents that might normally damage the peptidoglycans of the inner cell membrane; and lysozyme, an antimicrobial enzyme produced by animals that forms a part of the innate system.
The drugs that can effectively work on gram-negative organisms are aminoglycosides, monobactams (aztreonam), and ciprofloxacin.
So, the correct answer is ‘Lipopolysaccharide '.

Note: Gram-negative bacteria display these characteristics:
An inner cell wall is present.
A thin peptidoglycan layer is present which is far thicker in gram-positive bacteria.
Has an outer membrane containing lipopolysaccharides in its outer leaflet and phospholipids within the inner leaflet.
Porins exist within the outer membrane, which acts like pores for particular molecules.
Between the outer membrane and therefore the cytoplasmic membrane there's an area crammed with a concentrated gel-like substance called periplasm.