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Endoplasmic reticulum:the movement of materials around the cell.

They are the first organisms to be present on our planet earth. Organisms, with this cell type are known by the term prokaryotic organisms (or) prokaryotes. Bacteria, blue green algae and E.coli are few examples of this category. Prokaryotic cells are single-celled organisms, with the absence of nucleus and comprises of capsule, cell wall, cell membrane, cytoplasm, nucleiod, ribosome, plasmids, pili and flagella.

Prokaryotic Cell Structure

Prokaryotic Cell General Features

  • The size of a cell ranges from 1-10 microns. Few prokaryotic cells vary in their size.
  • They are single-celled (unicellular), which forms a colony or filamentous.
  • The shape of the cell includes spherical, rod and flat shaped organisms.
  • Mode of nutrients– few organisms are photosynthetic (performing food with the help of sunlight), feed on living things and dead things.
  • They reproduce asexually by the process called binary fission, transformation, conjugation, transduction.

Structure and Functions of a Prokaryotic Cell

Capsule: It is the slimy outer coating of the cell wall. It is composed of the polypeptide. The main function of the capsule is to protect the cell from getting dry and also helps in protecting cells from external pressures.

Cell wall: It is the tougher and a rigid structure, which provides the shape and protects the internal organelles of a cell. It is the middle layer, which is present in between the capsule and cell membrane.

Cell membrane: It is the inner delicate structure, which plays a vital role in regulating the entry and exits of materials in the cell. It acts a permeable membrane and separates the cell from its environment. It is of about 5-10nm in thickness, which helps in the secretion of proteins and elimination of waste products. It is also called by a name plasma membrane.

Cytoplasm: It is the liquid membrane, which is present in between the cell membrane and nucleiod. It plays a vital role in storing all types of materials, which are required for an organism to sustain the life.

Nucleiod: It is the cytoplasm region containing genetic material. The DNA of a prokaryotic organism is one big loop or a circular, which is located inside the nucleiod. It plays a vital role in cell division.

Ribosome: It  comprises of both RNA and proteins. It helps in protein synthesis in the cell. They are smallest membrane present inside the cytoplasm.

Plasmids: They are smallest membrane of a cell with double stranded DNA. Plasmids are rarely present in prokaryotic organisms. The main role of plasmids is it helps in DNA exchanging between the bacterial cells.

Pilli: It is the thinnest membrane of a prokaryotic cell. They are composed of protein complex called pilin and are mainly involved in sticking to the objects especially during sexual reproduction.

Flagella: It is the helical shaped membrane, whose sizes ranges from 19-20nm in diameter and plays a vital role in motility of an organism from one place to another place. It also helps in swimming, gliding, spinning and rotating both in clockwise and anti clockwise directions.