Prokaryotic Cell

Prokaryotic cells are simpler and smaller than the eukaryotic cells. The term prokaryote is derived from the Greek word- “prokaryote” meaning before nuclei. These cells lack membrane bound organelles. Prokaryotic cells are unicellular organisms, which reproduce through binary fission. In some cases few prokaryotic organisms also reproduce by budding. Prokaryotic cells have a cell envelope, which generally consists of a capsule, cell wall, cytoplasm, plasma membrane, cytoplasm region or nucleiod region, ribosome, plasmids, pili and flagella.

Example: Bacteria, blue green algae, E.coli, etc.

Parts of Prokaryotic Cell and their Functions

Capsule:  It is composed of a thick polysaccharide. It is a kind of slime layer, which covers the outside of the cell wall. It is used to stick cells together and works as a food reserve and it also protects the cell from dryness and from chemicals.

Cell wall: It is made from the glycoprotein murein. Cell wall provides strength and rigidity to the cell and it is permeable to solutes.

Cytoplasm:  It helps in cellular growth, metabolism and replication. Cytoplasm is the storehouses for all types of chemicals and components that are used to sustain the life of a bacterium.

Plasma membrane: It is also known as a cell membrane.It is mainly composed of proteins, phospholipids and carbohydrates, which forms into a fluid-mosaic. Plasma membrane surrounds the bacteria and it is a most important organelle and plays a vital role in controlling the movement of substances in the cell.

Cytoplasm region (or) nucleiod region: An area of the cytoplasm that contains the single bacterial DNA molecule.

Ribosome: They are the smallest part of cell organelle. Ribosome plays a vital role in protein synthesis as they consist of protein and RNA. They are located freely in the cytoplasm of attached to the rough endoplasmic reticulum.

Mesosomes: They are the folding, present inside the plasma membrane. Mesosome plays a vital role in cellular respirations, replication of DNA, cell division, separation of chromosomes during cell division and also performs the role of Golgi bodies and mitochondria.

Plasmids: They are a small circle of DNA. Plasmid plays a vital role in exchanging DNA between the bacterial cells. Bacterial cells have many plasmids.

Pili: They are short protein appendages, which fixes bacteria to surfaces. These pili are smaller than those flagella and are used in conjugation to exchange the genetic information.

Flagella: They are rigid rotating tail. The clockwise rotation moves the cell forward and anticlockwise rotation helps the cell to spin. The rotation is powered by H+ gradient across the cell membrane.