Question

Describe three mechanisms of regulation of gene expression in eukaryotes that are not used by prokaryotes. Give examples.

Answer 1

The regulation of gene expression in eukaryotes is complex process than the gene expression in prokaryotes. The prokaryotes lack a true nucleus. The nucleoid present in cytoplasm undergoes replication, transcription and translation within cytoplasm itself. The transcription and translation processes are coupled in prokaryotes. In eukaryotes the prominent nucleus is present. The DNA replication occurs within the nucleus. The transcription is the process of synthesis of mRNA from DNA. In eukaryotes, the synthesis of mRNA also occurs in nucleus. The synthesis of proteins occurs in cytoplasm and this can occur by export of mRNA from nucleus into cytoplasm. Thus, the transcription and translation are two separate processes that are physically separated.

In eukaryotes, the regulation of gene expression at various stages. The regulation of gene expression at DNA level occurs during the DNA uncoiling from nucleosomes allow the binding of transcription factors and this type of regulation is called epigenetic regulation. The epigenetics is accomplished by modification of histone proteins and include acetylation, deacetylation and methylation etc. The epigenetic regulation is more complex in eukaryotes than in prokaryotes. The eukaryotes gene regulation also occur at transcription and translation.

The post-transcriptional modifications such as poly A tail formation and 5' capping with 7- methyl guanosine and post- translational protein modifications are complex and unique than prokaryotes. The eukayotic genomes contain noncoding sequences called introns. During post transcriptional modifications, the introns are removed by splicing mechanism to produce protein encoding DNA sequence.Many of the gene regulatory mechanisms are complex and confined to eukaryotes because of complex genomes and also are distinct from prokaryotic mechanisms.