**Cell Organelles Unique to Prokaryotic Cells**

Prokaryotic cells are primitive and simpler than eukaryotic cells. They lack a distinct nucleus and other membrane-bound organelles. However, they do possess certain unique cell organelles that are not found in eukaryotic cells. These organelles play crucial roles in the survival and functioning of prokaryotic cells. Let's explore these organelles in detail:

**1. Nucleoid:**
The nucleoid is a distinct region within prokaryotic cells where the genetic material, typically a circular DNA molecule, is located. Unlike eukaryotic cells, prokaryotes lack a membrane-bound nucleus. The nucleoid contains the genetic information essential for the cell's replication and protein synthesis.

**2. Plasmids:**
Plasmids are small, circular strands of DNA that exist alongside the main chromosome within the nucleoid of prokaryotic cells. These extrachromosomal elements carry genes that provide additional functions to bacteria, such as antibiotic resistance or the ability to produce toxins. Plasmids can be transferred between prokaryotic cells, enabling the spread of beneficial traits.

**3. Ribosomes:**
While ribosomes are present in both prokaryotic and eukaryotic cells, prokaryotic ribosomes differ in size and composition. Prokaryotes have smaller ribosomes, known as 70S ribosomes, which consist of a 50S and a 30S subunit. In contrast, eukaryotic ribosomes are larger and comprise a 60S and a 40S subunit. This difference in ribosomal structure contributes to the effectiveness of certain antibiotics that selectively target prokaryotic ribosomes.

**4. Mesosomes:**
Mesosomes are invaginations or extensions of the prokaryotic cell membrane. They are not considered true organelles but play a crucial role in cellular processes. Mesosomes are involved in cellular respiration, DNA replication, and cell division. They provide a large surface area for attachment of enzymes and electron carriers involved in these processes.

**5. Gas Vesicles:**
Gas vesicles are gas-filled structures found in some prokaryotes, particularly aquatic bacteria. These vesicles enable the cells to regulate their buoyancy within the water column. By adjusting the gas content of the vesicles, prokaryotes can move up or down in the water column to access optimal light, nutrients, or oxygen concentrations.

In conclusion, prokaryotic cells possess several organelles that are not found in eukaryotic cells. These organelles, including the nucleoid, plasmids, ribosomes, mesosomes, and gas vesicles, contribute to the unique characteristics and functions of prokaryotic cells. Understanding these differences helps us appreciate the diverse adaptations of cells to their specific environments and lifestyles.

It does not contain membrane bound organelles or organelles