Question

How many layers are there in the cell envelope of Gram (-) ve bacteria?
A. 2
B. 3
C. 4
D. 6

Answer 1

Hint: The cell envelope is made up of the cell membrane, cell wall, and, if present, an outer membrane. This envelope is typically found in prokaryotes such as bacteria. It consists of a bacterium's inner cell wall and cell wall. The cell envelope is responsible for the cell's structural integrity. It protects the cell from internal turgor pressure caused by a high concentration of macromolecules inside the cell.

Complete answer:
A unicellular organism, similar to modern bacteria, was most likely one of the first organisms to evolve on Earth. Over many millennia, life has evolved into a diverse range of life forms. We can, however, trace our ancestors back to this single-celled organism.
Bacterial cell envelopes are classified into two types based on Gram staining: gram-positive and gram-negative. For added protection, either type may have a polysaccharide capsule enclosing it. These are referred to as polysaccharide encapsulated bacteria.
The gram-negative cell wall has a thinner peptidoglycan layer adjacent to the cytoplasmic membrane than the gram-positive wall, which accounts for the cell wall's inability to retain the crystal violet stain after ethanol decolorization during Gram staining.
In addition to the peptidoglycan layer, the gram-negative cell wall has an outer membrane made up of phospholipids and lipopolysaccharides that faces the outside world. Because of the highly charged nature of lipopolysaccharides, the gram-negative cell wall has an overall negative charge.
The chemical structure of the outer membrane lipopolysaccharides is frequently unique to specific bacterial strains (i.e. subspecies) and is responsible for many of these strains' antigenic properties.
Gram-negative bacteria have two membranes that are spatially separated. A periplasm and a peptidoglycan layer separate the outer membrane from the inner membrane. The ability to isolate these microbes' dual bilayers has been critical in understanding their physiology and pathogenesis.

Thus, the answer is Option A: 2.

Note:
Mycobacteria have a cell envelope that is not found in gram-positive or gram-negative bacteria. The Mycobacterial cell envelope lacks the outer membrane found in gram-negative bacteria, but it does have a significant peptidoglycan-arabinogalactan-mycolic acid wall structure that acts as an external permeability barrier. As a result, a distinct 'pseudo periplasm' is thought to exist.