原核和真核转录之间的差异

Thekey differencebetween prokaryotic and eukaryotic transcription is that核转录发生在细胞质而真核转录发生在细胞核内。

在细胞中，DNA一代地传递了控制细胞活性的世代信息。此外，DNA负责合成在细胞中具有功能和结构作用的所有蛋白质。因此，通过合成这种蛋白质，DNA控制细胞的活性。为了合成各自的蛋白质，应表达包含遗传信息产生蛋白质的遗传信息的基因。Gene expression通过两个主要步骤（即转录和翻译）发生。因此，转录是基因表达的第一步。其次是翻译。在转录过程中，有关DNA的遗传信息转化为mRNA中的三个字母遗传代码序列。在翻译过程中，mRNA转化为多肽链。

内容

1.Overview and Key Difference
2.什么是原核生物转录
3.What is Eukaryotic Transcription
4.Similarities Between Prokaryotic and Eukaryotic Transcription
5。Side by Side Comparison – Prokaryotic vs Eukaryotic Transcription in Tabular Form
6。概括

什么是原核生物转录?

Prokaryotic transcription takes place in the cytoplasm. Also, it is always occur coupled with translation. Transcription in the prokaryotic cell has four stages: binding, initiation, elongation and termination. RNA polymerase is the enzyme that catalyzes the synthesis of the mRNA strand. Binding of RNA polymerase to the promoter sequence is the first step in transcription. In a bacterial cell, only one kind of RNA polymerase exists which synthesizes all classes of RNA: mRNA, tRNA and rRNA. RNA polymerase found inEscherichia coli(E coli)由两个α亚基,两个β亚基d a sigma factor.

When this sigma factor binds to the DNA promoter sequence resulting in the unwinding of DNA double helix, initiation takes place. Using one of the DNA strands as a template, RNA polymerase synthesizes the RNA strand moving along the DNA strand unwinding the helix in the 5’ to 3’ direction. Hence, during the elongation step, this RNA strand grows from 5′ to 3′ forming a short hybrid with the DNA strand. Once the termination sequence meets, elongation of the mRNA sequence ceases. In prokaryotes, there are two types of termination; factor-dependent termination and intrinsic termination. Factor dependent termination needs Rho factor, and intrinsic termination happens when the template contains a short GC rich sequence near the 3′ end after several uracil bases.

什么是真核转录？

Eukaryotic transcription takes place in the nucleus. Similar to prokaryotic transcription, eukaryotic transcription also occurs via four steps, i.e. binding, initiation, elongation and termination. However, eukaryotic transcription is more complex than the prokaryotic transcription.

In a eukaryotic cell, three different kinds of RNA polymerases are present; they are namely,RNA pol I, II and III它们与它们合成的RNA的位置和类型不同。RNA聚合酶借助转录因子与启动子区域的DNA结合。当DNA螺旋将单链解开时，RNA聚合酶会催化从模板链中的mRNA序列的合成。这种RNA链从5'到3'，形成与DNA链的短杂种，这称为伸长率.Elongation is ceased with the transcription of a special sequence called a termination signal. Termination is controlled by a variety of signals which vary with the enzyme involved.

Moreover, the initial RNA sequence that results from the transcription is a premature RNA sequence. It contains junk sequences. Hence, prior to translation, some modifications occur in order to produce mature mRNA. These modifications include RNA splicing, 5’ capping, 3’ adenylation, etc. Once the modifications happen, mRNA sequence travels to the cytoplasm. Unlike in prokaryotes, eukaryotic transcription does not occur simultaneously with the translation.

原核和真核转录之间有什么相似之处？

• 原核和真核转录都遵循相同的机制。
• 而且，两者都有类似的步骤。
• At the end of both processes, an mRNA is produced.
• Furthermore, RNA polymerase catalyzes both transcription processes.
• 此外，两个过程都使用DNA模板产生mRNA序列。

What is the Difference Between Prokaryotic and Eukaryotic Transcription?

Prokaryotic transcription takes place in the cytoplasm. On the other hand, eukaryotic transcription takes place in the nucleus. This is the key difference between prokaryotic and eukaryotic transcription. Furthermore, prokaryotic transcription produces多水mRNA而真核转录产生单科发电频率mRNA。因此，这也是原核生物和真核转录之间的差异。同样，原核和真核转录之间的另一个差异是，原核转录涉及一种RNA聚合酶，而真核转录涉及三种类型的RNA聚合酶。

Moreover, another difference between prokaryotic and eukaryotic transcription is that the transcription and翻译are coupled in prokaryotes while they are not coupled in eukaryotes. Furthermore, in prokaryotes, post-transcriptional modifications are not taking place while in eukaryotes, post-transcriptional modification occurs. Thus, it is also a difference between prokaryotic and eukaryotic transcription.

在原核生物和真核转录之间差异的信息图下面提供了有关差异的更多信息。

摘要 - 原核生物与真核转录

转录是基因表达的第一步，随后是翻译。尽管在原核生物和真核生物中的转录机制是相同的，但它们之间有几个差异。原核和真核转录之间的主要区别在于，核转录发生在细胞质中，而真核转录发生在细胞核中。此外，核转录仅涉及一个RNA聚合酶，而真核转录涉及三种类型的RNA聚合酶。此外，原核生物的mRNA序列是多余的，而在真核生物中，mRNA序列是单科的。不仅如此，在真核生物中，在原核生物中进行了转录后修饰，它们不会发生。这是原核生物和真核转录之间差异的摘要。

Reference:

1. Cooper, Geoffrey M. “Transcription in Prokaryotes.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 1 Jan. 1970.Available here
2.“真核转录。”。Wikipedia，Wikimedia基金会，2019年1月17日。Available here

Image Courtesy:

1. Joan L. Slonczewski，John W. Foster - 微生物学：不断发展的科学，(CC BY-SA 3.0)viaCommons Wikimedia
2.弗兰克·史泰默（Frank Starmer）的“真核转录”(CC BY 1.0)viaCommons Wikimedia