what is meant by cell envolop
Answers
Cell envelope is a combination of the cell membrane, cell wall, and an outer membrane if it is present. Usually, this envelope is a characteristic of prokaryotes like bacteria. Hence, the composition would be cell membrane, bacterial cell wall and bacterial outer membrane (made of glycocalyx). Although the three layers have distinct functions, they act together as a protective unit for the bacterial cells. Based on the differences in the envelopes and the manner in which they respond to Gram’s staining procedure, bacterial cells are termed as Gram-positive if they take up the stain and as Gram-negative if they don’t. Thickness and composition of glycocalyx vary among bacterial species. In certain bacteria like pneumonia-causing Streptococcus pneumoniae, it is present as a loose sheath known as a slime layer. In others, it is thicker and sturdy known as capsule as found in Pseudomonas aeruginosin.