Prokaryotic cells are the cells that do not have a membrane-bound nucleus. They are simple and primitive cells that lack various membrane-bound organelles found in eukaryotic cells. Prokaryotic cells are found in bacteria and archaea, two of the three domains of life.

Structure of Prokaryotic Cells:
Prokaryotic cells have a simple structure compared to eukaryotic cells. They consist of the following components:

1. Cell Wall: Prokaryotic cells have a rigid cell wall composed of peptidoglycan, which provides support and protection to the cell.

2. Plasma Membrane: The plasma membrane is a thin, flexible lipid bilayer that encloses the cell and regulates the movement of materials in and out of the cell.

3. Cytoplasm: The cytoplasm is a gel-like substance that fills the cell. It contains enzymes, ribosomes, and other cellular components.

4. Ribosomes: Ribosomes are the sites of protein synthesis in the cell. They are smaller in size compared to eukaryotic ribosomes.

5. Genetic Material: Prokaryotic cells have a single circular DNA molecule called the nucleoid, which contains the genetic information of the cell.

6. Flagella: Some prokaryotic cells have flagella, which are whip-like structures used for movement.

7. Pili: Pili are short, hair-like appendages that help bacteria attach to surfaces or other cells.

Functions of Prokaryotic Cells:
Prokaryotic cells play crucial roles in various ecological processes. Some of their functions include:

1. Reproduction: Prokaryotic cells reproduce through binary fission, a process where a single cell divides into two identical daughter cells.

2. Metabolism: Prokaryotes carry out essential metabolic processes such as respiration, photosynthesis, and fermentation.

3. Nutrient Cycling: Prokaryotes play a vital role in the cycling of nutrients in ecosystems. They decompose organic matter and recycle nutrients back into the environment.

4. Symbiotic Relationships: Some prokaryotes form mutually beneficial relationships with other organisms. For example, nitrogen-fixing bacteria form symbiotic associations with plants, providing them with essential nutrients.

5. Pathogenicity: Certain prokaryotes can cause diseases in humans, animals, and plants. They possess virulence factors that enable them to invade and damage host tissues.

In conclusion, prokaryotic cells are the cells that lack a membrane-bound nucleus. They have a simple structure and perform various essential functions necessary for the survival and functioning of organisms.

The cell without membrane is called prokaryotic cell