Give a detailed account of prokaryotic cell highlighting the role of its
different organelles .
Answers
Answer:
Prokaryotic Cells
Prokaryotic cells are cells without a nucleus. The DNA in prokaryotic cells is in the cytoplasm rather than enclosed within a nuclear membrane. Prokaryotic cells are found in single-celled organisms, such as bacteria, like the one shown in the Figure below. Organisms with prokaryotic cells are called prokaryotes. They were the first type of organisms to evolve and are still the most common organisms today.
Cell Wall
While some eukaryotic cells have cell walls, such as those in plants and fungi, almost all prokaryotic cells have them, and they are chemically distinct from those of eukaryotes. The walls give the organism stability, protection and its overall shape. The walls of bacteria consist of substances called peptidoglycans. Some prokaryotes have an outer capsule outside the cell wall, resulting in three layers from outside to inside: capsule, wall and membrane. Certain antibiotics, including penicillin drugs, target the cell walls of bacteria.
Cell Membrane
The cell membrane, which is common to all living things, consists of a structure called a phospholipid bilayer. It is so named because it includes two layers, each containing hydrophilic, or water-soluble, phosphate "heads" that face away from the middle of the membrane and hydrophobic "tails" that are not water soluble and face each other on the interior of the double layer. The membrane is selectively permeable, meaning that some substances may pass through, often with the help of protein "motors" embedded in the membrane but at other times via simple diffusion.
Cytoplasm
Also called the cytosol, the cytoplasm of a cell is a gel-like substance consisting predominantly of water. It also contains enzymes, salts, an assortment of organic molecules and the cell's organelles. In this medium, a number of chemical reactions can take place. If you imagine a water balloon filled with a mixture of water and shaving cream being a cell, the rubber represents the cell wall and cell membrane and the water and shaving cream, in which other organelles are found, represents the cytoplasm.
Ribosomes
Ribosomes are organelles responsible for protein synthesis, a process that every cell must undertake to ensure the survival of the organism, whatever its overall size, shape and function. Each ribosome consists of a large subunit and a small subunit, both of which include ribosomal RNA (rRNA) and proteins. In protein synthesis, messenger RNA (mRNA) moves through the ribosome like a conveyor belt, while amino acids attached to transfer RNA (tRNA) are carried to the ribosome. The amino acids are then attached to assemble the complete protein.