Eukaryotic gene transcription is the process by which the genetic information encoded in the DNA is transcribed into a complementary RNA molecule. This RNA molecule can then be used to synthesize proteins through the process of translation. The steps and enzymes involved in eukaryotic gene transcription include:
1. Initiation:
- RNA Polymerase II (RNAP II): This enzyme recognizes the promoter sequence on the DNA and binds to it, along with various transcription factors.
- Transcription Factors: These proteins help recruit and position the RNAP II complex at the promoter region.
2. Promoter clearance:
- TFIIH: This transcription factor complex unwinds the DNA double helix near the promoter region, which allows the RNAP II complex to begin transcribing the DNA template.
3. Elongation:
- RNAP II: Once the RNA polymerase complex is properly positioned and the DNA strand is unwound, RNAP II begins synthesizing the RNA molecule using the DNA template strand as a guide.
- NTPs (nucleoside triphosphates): These are the building blocks of the RNA molecule and are added sequentially to the growing RNA chain.
4. Termination:
- Termination signal: After the RNA polymerase has transcribed the entire gene, a termination signal is encountered, which causes the release of the RNA polymerase from the DNA template.
- Termination factors: These proteins help in the recognition and binding of termination signals, facilitating the termination of transcription.
It is important to note that eukaryotic gene transcription is a complex process that involves the interplay of multiple proteins and regulatory elements. Additionally, various post-transcriptional modifications, such as RNA splicing and processing, can occur to produce a mature RNA molecule before it is exported from the nucleus for translation.
7.Eukaryotic gene transcription, its steps, enzymes involved in its mechanism
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what is the main difference between prokaryotic transcription and eukaryotic transcription
The main difference between prokaryotic and eukaryotic transcription lies in the complexity of the process and the regulatory mechanisms involved. Here are some key differences:
1. Compartmentalization: In prokaryotes, transcription occurs in the cytoplasm since there is no nuclear membrane to separate the DNA from the rest of the cellular components. In eukaryotes, transcription mainly takes place in the nucleus, where the DNA is housed.
2. Gene Structure: Prokaryotes typically have genes that consist of a coding region, referred to as the operon, without introns. In contrast, eukaryotic genes are more complex, usually containing introns (non-coding regions) that need to be removed by mechanisms such as RNA splicing.
3. Transcription Factors: Prokaryotes have fewer transcription factors involved in gene regulation. Eukaryotes, on the other hand, have a more elaborate system of transcription factors that control gene expression by binding to specific regions on the DNA and recruiting RNA polymerase II.
4. Promoter Recognition: Prokaryotic transcription primarily relies on a specific DNA sequence called the promoter, typically found upstream of the coding region. Eukaryotic transcription, however, involves the recognition of more complex promoter sequences that are recognized by multiple transcription factors.
5. RNA Polymerase: Prokaryotes generally have a single RNA polymerase enzyme responsible for transcription. Eukaryotes have multiple RNA polymerases: RNA polymerase I transcribes ribosomal RNA genes, RNA polymerase II transcribes protein-coding genes, and RNA polymerase III transcribes transfer RNA genes and other small functional RNAs.
6. Post-Transcriptional Modifications: Eukaryotic transcription involves extensive post-transcriptional modifications of the initial RNA molecules. These include 5' capping, 3' polyadenylation, and RNA splicing to remove introns and join exons together. Prokaryotic transcription does not typically involve these modifications.
The differences in transcription between prokaryotes and eukaryotes reflect the complexity and diversity of gene regulation in eukaryotic organisms.
1. Compartmentalization: In prokaryotes, transcription occurs in the cytoplasm since there is no nuclear membrane to separate the DNA from the rest of the cellular components. In eukaryotes, transcription mainly takes place in the nucleus, where the DNA is housed.
2. Gene Structure: Prokaryotes typically have genes that consist of a coding region, referred to as the operon, without introns. In contrast, eukaryotic genes are more complex, usually containing introns (non-coding regions) that need to be removed by mechanisms such as RNA splicing.
3. Transcription Factors: Prokaryotes have fewer transcription factors involved in gene regulation. Eukaryotes, on the other hand, have a more elaborate system of transcription factors that control gene expression by binding to specific regions on the DNA and recruiting RNA polymerase II.
4. Promoter Recognition: Prokaryotic transcription primarily relies on a specific DNA sequence called the promoter, typically found upstream of the coding region. Eukaryotic transcription, however, involves the recognition of more complex promoter sequences that are recognized by multiple transcription factors.
5. RNA Polymerase: Prokaryotes generally have a single RNA polymerase enzyme responsible for transcription. Eukaryotes have multiple RNA polymerases: RNA polymerase I transcribes ribosomal RNA genes, RNA polymerase II transcribes protein-coding genes, and RNA polymerase III transcribes transfer RNA genes and other small functional RNAs.
6. Post-Transcriptional Modifications: Eukaryotic transcription involves extensive post-transcriptional modifications of the initial RNA molecules. These include 5' capping, 3' polyadenylation, and RNA splicing to remove introns and join exons together. Prokaryotic transcription does not typically involve these modifications.
The differences in transcription between prokaryotes and eukaryotes reflect the complexity and diversity of gene regulation in eukaryotic organisms.