Differences between Prokaryotes and Eukaryotes


Both prokaryotes and eukaryotic genomes are DNA genomes. Prokaryotic genome is usually found on the cytoplasm and consists of only one chromosome, while the eukaryotic one consists of multiple chromosomes and most of the eukaryotic genome is found on the nucleus. Prokaryotic genome is less complex compared to the eukaryotic one which generally consists of longer genes. The coding sequences compart nearly the 90% of the prokaryotic genome and only the 3% of the eukaryotic genome. The prokaryotic genome tends to be circular, while the eukaryotic genomes are generally linear. The prokaryotic genomes are always haploid, but the eukaryotes can be either diploid or haploid. Compared to the eukaryotic genomes, the prokaryotic genomes have a high rate of protein coding genes. Furthermore, the eukaryotic genome has hundreds of rRNA genes compared to the prokaryotic ones that have 1-10 rRNA genes. Eukaryotic genomes have a higher rate of repeated sequences, end telomeres and introns compared to the prokaryotic genomes that rarely consist of those parts. Also origin of replications usually are numerous on eukaryotes but found only once in prokaryotes.[1]. Both eukaryotic and prokaryotic gene structures include similar sequence elements necessary for gene expression. They both involve regulatory elements such as promoters, silenceres and enhancers usually on their ends and contain ORI. Also the reading strands of both eukaryotic and prokaryotic strands is on the 5′-3′ direction. Eukaryotic genes differ from prokaryotic genes because introns are absent in prokaryotic genes and in prokaryotic genes there is no such a phenomenon such as alternative splicing. Also eukaryotic genes consist of more regulatory regions compared to the prokaryotic ones. In prokaryotes the genes can sometimes organize themselves in a polycistronic operon. Riboswitches also are some regulatory regions of the prokaryotic genes that lack on the eukaryotic genes. The main difference of the RNA polymerase II assisted transcription initiation is that in prokaryotes only DNA containing promoter and polymerase II are needed, while in eukaryotes several transcription initiation factors and proteins more are needed, such as TF, TBP, TFIID, TAF[2].

References

1-http://www.differencebetween.com/difference-between-prokaryotic-and-vs-eukaryotic-genome/

2 – https://www.ncbi.nlm.nih.gov/books/NBK9935/

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