Comparing Prokaryotic And Eukaryotic Cells

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1. Compare and contrast prokaryotic and eukaryotic cells. Be sure to address cell structure, replication (including DNA replication) and gene expression.
The cell structure of prokaryotic organisms is small, only about 1-10 microns in length, and they are also single celled. Prokaryotes contain circular DNA which is held in the nucleoid because they lack a nucleus. The specific organisms that have circular DNA are: mitochondrial, bacterial (eubacteria), and Archaea (Methanobacteria, Halobacteria, and sulfobacteria). Prokaryotes have no membrane-bound organelles because they have no organelles. Their ribosomal subunits are 50S and 30S which come to equal 70S, and their plasma membrane does not contain sterols. In prokaryotes, there is one large vacuole per cell which takes up 50-90% of cell and serves as a reservoir for water; this helps hold turgor pressure in plants. Prokaryotes also cannot go through endo- or exocytosis, and their cell wall is made of peptidoglycan. The replication properties of prokaryotes includes Theta Mode Replication, in which there is only a single origin of replication, but two replication forks. The Okazaki Frangments are 1000-2000 base pairs in length, and the formation of the cell plate is done by the phragmosome. Proteins and RNA help the DNA to fold proteins because prokaryotes do not have histones. Transcription and translation occur simultaneously because prokaryotes have no plasma membrane, therefore no posttranscriptional modifications

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