General organization of prokaryotic and eukaryotic cells

Cell

All living systems (plants and animals) are made of cells. Cells are the smallest unit of life. A cell is composed of a variety of molecules and molecular aggregates. The chemical molecules present in the cell and which have the direct relationship with the activities of the cell are called biochemical molecules or biomolecules. The collection of molecules in a cell is called cellular pool. The cell is the basic structural and functional units of the living organism. It consists of the microscopic mass of protoplasm surrounded by a cell membrane. It is the smallest unit, that can carry on all the processes of life.

The general organization of prokaryotic and eukaryotic cells.

The distinction between prokaryotes and eukaryotes is considered to be the most important distinction among the group of organisms. Eukaryotic cells contain membrane-bound organelles such as the nucleus, while prokaryotic cell do not.

Differences in the cellular structure of prokaryotic and eukaryotic include the presence of the mitochondria and the chloroplasts, the cell wall, and the structure of chromosomal DNA. Prokaryotes were the only form of life on the Earth for millions of years until more complicated eukaryotic cells came into being through the process of evolution. Comparison chart:

Definition of eukaryotes and prokaryotes: Prokaryotes (pro-KAR-ee-ot-es) (from old Greek pro-before + Karyon nut or kernel, referring to the cell nucleus, + suffix-notes ; also spelled prokaryotes) are organisms without a cell nucleus (=karyon), or any other membrane-bound organelles. Most of them are unicellular, but some prokaryotes are multicellular. Eukaryotes are organisms which cells are organized into the complex structures by internal membranes and a cytoskeleton. The most characteristic membrane bound structure is the nucleus.That feature gives them their name (also called “eucaryote,”) which comes from the greek word Eu, meaning good/true, and Karpov, meaning nut, referring to the nucleus. Animals, plants, fungi, and protists are eukaryotes.

Differences between the Eukaryotic and Prokaryotic cells

The differences between the structure of the prokaryotes and the eukaryotes are so greater that it is considered to be the most important distinction among the group of organisms. Structure and content of a typical gram-positive bacterial cell (a prokaryotic cell). The most fundamental differences are that eukaryotes do have true nuclei containing their DNA whereas the genetic material in prokaryotes is not membrane-bounded. In the eukaryotes, mitochondria and chloroplasts perform various metabolic processes and are believed to have been derived from the endosymbiotic bacteria. In prokaryotes, similar processes occur across the cell membrane. The cell walls of prokaryotes are generally formed of a different molecule (peptidoglycan) to those of eukaryotes (many of eukaryotes do not have the cell wall at all). Prokaryotes are usually smaller than eukaryotic cells. The Prokaryotes also differ from the eukaryotes in that they contain only a single loop of stable chromosomal DNA stored in an area named the nucleoid, while eukaryotic DNA is found on tightly bound and organized chromosomes. Although some eukaryotes have the satellite DNA structures called as plasmids, these are generally regarded as a prokaryote feature and many important genes in the prokaryotes are stored in the plasmids. Prokaryotes have a larger surface area of the volume ratio giving them a higher metabolic rate, the higher growth rate and the consequently a shorter generation time compared to Eukaryotes.

Genes prokaryotes also differ from the eukaryotes in the structure, packing, density and arrangement of their genes on the chromosome. Prokaryotes have incredibly compact genomes compared to eukaryotes, mostly because prokaryote genes lacks large non-coding regions between each gene. Whereas nearly 95% of the human genome does not code for the proteins or the RNA or includes a gene promoter, nearly all of the prokaryote genome codes or controls something. Prokaryote genes are also expressed in the groups known as the operons, instead of individually as in eukaryotes. In a prokaryote cell, all genes in an operon (three in the case of the famous lac operon) are transcribed on same piece of the RNA and then made into separate proteins, whereas if these genes were native to the eukaryotes, they would have their own promoter and be transcribed on their own strand of the mRNA. This lesser degree of the control over gene expression contributes to the simplicity of the prokaryotes to compared with the eukaryotes.

References

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