Gram-Negative bacteria Cell Envelope

The Gram-Negative Cell Envelope is a complex multi-layered structure that shields organisms from external hostile environments and living conditions. In doing so, the Gram-Negative Cell Envelope plays a significant role in the survival of the bacteria. The Gram-Negative Cell Envelope comprises a thin peptidoglycan cell wall, and an outer membrane consisting of lipopolysaccharides protects the thin wall. The theory of the Gram-Negative Cell Envelope was proposed by Christian Gram in 1884 after he developed a procedure that allowed him to classify almost every bacteria into two large groups: Gram-Positive and Gram-Negative. 

Body:

The Bacterial Cell Envelopes are external structures surrounding and protecting the cytoplasm from hostile external conditions. The Bacterial Cell Envelopes are essential because bacterial groups often expose themselves to unpredictable and hostile living environments. 

Over the past several thousand years, Bacterial groups have evolved, and they have grown a complex, sophisticated cell envelope to shield themselves from these unfavourable living conditions. These cell envelopes protect bacteria from extreme conditions, but they also allow the passage of nutrients from the outside and the transfer of waste products from the inside. 

Christian Gram first proposed the theory of Gram-Negative Cell Envelope in the late 19th century. However, it was only in the 1950s when scientists were able to reveal a clear structure of the Gram-Negative Cell Envelope thanks to advancements in electron microscopy. 

The Gram-Negative Cell Envelope of a Bacteria is a multi-layered structure that consists of the following three parts: 

1. Dual layer-based plasma membrane. 
2. A periplasm of soluble proteins, membrane-derived oligosaccharides, and a peptidoglycan mesh. 
3. An outer membrane with a unique structure consisting of proteins and lipids. 

Each part of the structure plays its unique role. The inner plasma membrane allows selective transportation of nutrients and waste between the cell and the external environment. On the other hand, the Periplasm is an aqueous space between the inner and the outer membranes. The Periplasm plays a vital role in providing the cell with its unique shape, supports the overall structure of the cell, and anchors the outer lipoprotein membrane. The Gram-Negative Cell Diagram Envelope was essential to scientists because it opened several opportunities for studying lipid topogenesis and protein. 

Outer Membrane

Let’s start with the outer membrane. The outer membrane is a unique feature of the Gram-Negative Cell Envelope, as it is not present in the Gram-Positive Cell Envelope. The Outer Membrane is a lipid bilayer and not a phospholipid bilayer. However, this does not mean that the outer membrane does not contain phospholipids. It is so because phospholipids limit themselves to the inner linings of this membrane. 

The outer linings of the outer membrane consist mainly of glycolipids, more specifically, “Lipopolysaccharide or LPS.” The Lipopolysaccharide or LPS does not enjoy a good reputation because scientists have confirmed that LPS is responsible for endotoxic shocks in Gram-Negative organisms. 

The Periplasm

The Periplasm is an aqueous cellular compartment that lies in the space between the inner and the outer membranes. The Periplasm is known to be highly dense in protein molecules, and its viscosity is higher than the cytoplasm as well. The Periplasm has gained the title of eukaryotic cells’ evolutionary precursor of the lysosomes because they allow Gram-Negative Bacteria to isolate potentially degradative, hazardous enzymes alkaline phosphatase and RNAse. Another essential protein found in the aqueous region of the Periplasm is the Periplasmic Binding Protein—these Periplasmic Building Proteins help in the transportation of amino acids and sugar. 

The Inner Membrane

One of the highlighting features of the Eukaryotic Cells is limiting membranes of intracellular organelles. These intracellular organelles are limiting membranes that play a significant role in several critical cellular processes. Mitochondria is the powerhouse of the cell, and it completes the task of producing energy; ER or Endoplasmic Reticulum synthesises lipids, protein secretion takes place in the rough Endoplasmic Reticulum. 

The Cytoplasmic Membrane in the Gram-Negative Cell Envelope houses the receptors that sense the current environmental conditions. It also activates the transportation system to transport waste and nutrients between the cell and the external environment. One of the primary reasons why the membrane-related functions of the eukaryotic organelles take place in the Internal Membrane is because the Bacteria lack intracellular organelles. 

Several membrane proteins that help in energy production, protein secretion, lipid biosynthesis, and transportation preserve themselves in the bacteria but with different cellular locations. 

Conclusion:

The Gram-Negative Cell Envelope is a complex multi-layered structure that protects organisms from hostile environments and unpredictable living conditions. 

The Gram-Negative Cell Envelope Diagrams generated in the 1950s revealed that a Gram-Negative Cell Envelope comprises three main structural parts: The Inner Membrane, the Periplasm, and the Outer Membrane. These structures play an essential role in ensuring the survival of Bacteria. 

The Outer Membrane is a unique feature of the Gram-Negative Bacteria, and it is a lipid bilayer. The Periplasm allows a Gram-Negative Bacteria to isolate potentially degradative, hazardous enzymes alkaline phosphatase, and RNAse. Finally, the Inner Membrane houses the receptors that activate the transportation system to transport waste and nutrients between the cell and the external environments.