Question

Murein of bacterial cell wall is derivative of
(A) Vitamins
(B) Fats
(C) Organic Acid
(D) Sugar

Answer 1

Hint: A cell wall is a layer located immediately outside the cell membrane, commonly found in plants, fungi, bacteria, algae and archaea. In bacteria, the cell wall is primarily made of peptidoglycans or murein, which is their characteristic feature.

Complete answer:
Murrain is a heteropolymer made of sugars and amino acids. The sugar component consists of linear glycan strands of alternating linked N-acetylglucosamine(NAG) and N-acetyl muramic acid (NAM) residues. The NAM residue has peptide chains of three to five amino acids attached to it. These peptides cross-link with each other, forming a mesh like structure.

Hence, the correct answer is option (D).

Note: Based on the peptidoglycan in the cell wall, bacteria are divided into two types as gram positive and gram negative bacteria. They can be identified by using gram staining methods. The cells of gram-positive bacteria are thick with multiple layers of peptidoglycan with teichoic acids and phosphate. This teichoic acid is responsible for the rigidity of the cell wall.
However, gram negative bacteria are thin and possess peptidoglycan which constitute just a few layers and lacks teichoic acid. In these cells, a plasma membrane layer is present. The outer membrane has a lipid bilayer that resembles the cell membrane composition that has polar heads, fatty acid tails and integral proteins.
Some bacteria lack peptidoglycan. Phylum Chlamydiae lacks peptidoglycan despite the fact that their cell walls are gram negative.
Some of the functions of cell wall in bacteria are:
-It maintains the cell shape and provides rigidity and structural support to the cells.
-It allows bacterial cells to withstand the internal turgor pressure where the cell pushes the plasma membrane against the cell.