Eukaryotic exons may be spliced in alternative patterns
Gene expression can be controlled at any of several stages, which we divide broadly into transcription, processing and translation. Transcription often is controlled at the stage of initiation, or at termination but usually not controlled at elongation. In eukaryotic cells, processing of the RNA product may be regulated at the stages of modification, splicing, transport, or stability. Translation may be regulated, usually at the stages of initation and termination just like transcription. Gene expression can be controlled at any of several stages, as during transcription, processing and translation. Transcription often regulated at initiation and termination but elongation is usually not regulated. In eukaryotes cells, processing of the RNA product may be regulated at the stages of modification, splicing, transport, or at stability. Translation may be regulated at initiation and termination just like transcription.
In eukaryotes, mRNA is processed inside the nucleus before being shipped out into the cytoplasm for translation. Specifically, a strand of pre-mRNA (or immature mRNA) has a GTP cap added to its 5' end, a poly-adenine tail added to its 3' end, and it has its introns spliced out. Since prokaryotes don't have nuclear envelopes, they don't have an area to do this.
The terms eukaryote and prokaryote refer to the two distinct types of organisms found in the natural world. Eukaryotes are organisms that have a membrane-bound nucleus, while prokaryotes are organisms that lack a membrane-bound nucleus. This difference in structure suggests that the evolution of eukaryotes, which are more complex and structurally organized, preceded the evolution of prokaryotes, which are simpler and more primitive. Eukaryotes are believed to have evolved from an ancestor that contained a nucleus, which was a critical step in the evolution of life as it allowed for more efficient storage and processing of genetic information. Prokaryotes, on the other hand, had no nucleus and were likely the first form of life on Earth. This suggests that the evolution of prokaryotes followed the evolution of eukaryotes. Overall, the terms eukaryote and prokaryote suggest that eukaryotes are more complex and evolved prior to prokaryotes, which are simpler and more primitive.
In prokaryotes, transcription occurs in the cytoplasm since they lack a nucleus, while in eukaryotes, transcription occurs in the nucleus. Prokaryotic transcription is often coupled with translation, meaning ribosomes can start translating mRNA even before transcription is complete, whereas in eukaryotes, transcription and translation are spatially and temporally separated. Prokaryotic mRNA does not typically undergo extensive processing (such as splicing or capping) after transcription, whereas eukaryotic mRNA is extensively processed before being translated.
Eukaryotes exhibit control mechanisms at all levels, including transcriptional, transcript processing, translational, and post-translational regulation. These mechanisms work together to finely regulate gene expression and protein production in response to various internal and external signals.
In prokaryotes, gene expression can be regulated directly at the level of transcription through operons, where multiple genes are controlled by a single promoter. This type of regulation is not as common in eukaryotes, where gene expression is typically regulated at multiple levels, including transcription, RNA processing, translation, and post-translational modifications. Additionally, prokaryotes lack the complexity of chromatin structure found in eukaryotic cells, which can also impact gene expression regulation.
Gene expression can be controlled at any of several stages, which we divide broadly into transcription, processing and translation. Transcription often is controlled at the stage of initiation, or at termination but usually not controlled at elongation. In eukaryotic cells, processing of the RNA product may be regulated at the stages of modification, splicing, transport, or stability. Translation may be regulated, usually at the stages of initation and termination just like transcription. Gene expression can be controlled at any of several stages, as during transcription, processing and translation. Transcription often regulated at initiation and termination but elongation is usually not regulated. In eukaryotes cells, processing of the RNA product may be regulated at the stages of modification, splicing, transport, or at stability. Translation may be regulated at initiation and termination just like transcription.
Prokaryotes do not have a distinct nucleus, so transcription and translation both occur in the cytoplasm simultaneously. In eukaryotes, transcription occurs in the nucleus while translation occurs in the cytoplasm, separated by nuclear envelope. Furthermore, eukaryotes have additional complexity due to post-transcriptional modifications and protein processing that prokaryotes lack.
Post-translational modifications of proteins do occur in prokaryotes, but they are generally less complex than in eukaryotes. Prokaryotes lack certain cellular compartments where modifications like glycosylation occur in eukaryotes. Additionally, prokaryotes have simpler metabolic pathways that may not require extensive post-translational modifications for protein function.
In eukaryotes, mRNA is processed inside the nucleus before being shipped out into the cytoplasm for translation. Specifically, a strand of pre-mRNA (or immature mRNA) has a GTP cap added to its 5' end, a poly-adenine tail added to its 3' end, and it has its introns spliced out. Since prokaryotes don't have nuclear envelopes, they don't have an area to do this.
The terms eukaryote and prokaryote refer to the two distinct types of organisms found in the natural world. Eukaryotes are organisms that have a membrane-bound nucleus, while prokaryotes are organisms that lack a membrane-bound nucleus. This difference in structure suggests that the evolution of eukaryotes, which are more complex and structurally organized, preceded the evolution of prokaryotes, which are simpler and more primitive. Eukaryotes are believed to have evolved from an ancestor that contained a nucleus, which was a critical step in the evolution of life as it allowed for more efficient storage and processing of genetic information. Prokaryotes, on the other hand, had no nucleus and were likely the first form of life on Earth. This suggests that the evolution of prokaryotes followed the evolution of eukaryotes. Overall, the terms eukaryote and prokaryote suggest that eukaryotes are more complex and evolved prior to prokaryotes, which are simpler and more primitive.
In prokaryotes, transcription occurs in the cytoplasm since they lack a nucleus, while in eukaryotes, transcription occurs in the nucleus. Prokaryotic transcription is often coupled with translation, meaning ribosomes can start translating mRNA even before transcription is complete, whereas in eukaryotes, transcription and translation are spatially and temporally separated. Prokaryotic mRNA does not typically undergo extensive processing (such as splicing or capping) after transcription, whereas eukaryotic mRNA is extensively processed before being translated.
Eukaryotes exhibit control mechanisms at all levels, including transcriptional, transcript processing, translational, and post-translational regulation. These mechanisms work together to finely regulate gene expression and protein production in response to various internal and external signals.
The transcription in eukaryotes, a much more complex process than in prokaryotes. In eukaryotes, transcription and translation take place in different cellular compartments:transcription takes place in the membrane-bounded nucleus, whereas translation takes place outside the nucleus in the cytoplasm. In prokaryotes, the two processes are closely coupled. Indeed, the translation of bacterial mRNA begins while the transcript is still being synthesized. The spatial and temporal separation of transcription and translation enables eukaryotes to regulate gene expression in much more intricate ways, contributing to the richness of eukaryotic form and function.A second major difference between prokaryotes and eukaryotes is the extent of RNA processing. Although both prokaryotes and eukaryotes modify tRNA and rRNA, eukaryotes very extensively process nascent RNA destined to become mRNA. Primary transcripts (pre-mRNA molecules), the products of RNA polymerase action, acquire a cap at their 5′ ends and a poly(A) tail at their 3′ ends. Most importantly, nearly all mRNA precursors in higher eukaryotes are spliced. Introns are precisely excised from primary transcripts, and exons are joined to form mature mRNAs with continuous messages. Some mRNAs are only a tenth the size of their precursors, which can be as large as 30 kb or more. The pattern of splicing can be regulated in the course of development to generate variations on a theme, such as membrane-bound and secreted forms of antibody molecules. Alternative splicing enlarges the repertoire of proteins in eukaryotes and is a clear illustration of why the proteome is more complex than the genome.
In prokaryotes, DNA is stored in the cytoplasm. also prokaryotes have no nucleus In prokaryotes, transcription and translation happen at the same time.
Prokaryotic mRNA lacks a 5' cap and 3' poly(A) tail because it undergoes rapid degradation in the cell. Prokaryotes do not have the same mRNA processing machinery as eukaryotes, so they rely on different mechanisms for stability and translation initiation, such as internal ribosome binding sites (RBS) and RNA-binding proteins.
The prime advantage of eukaryotic organisms is compartmentalization. By having compartments the eukaryotic organism can concentrate and refine specialized biochemical processes, improve overall capabilities and efficiencies and improve overall fitness.