Difference Between Upstream and Downstream DNA

Key Difference – Upstream vs Downstream DNA

It is important to have a general knowledge about the composition and structure of脱氧核糖核酸为了了解上游和下游DNA之间的差异。DNA由多核苷酸链组成。核苷酸are the building blocks which create polynucleotide chains and each nucleotide is made from three components: a five-carbon sugar, a nitrogenous base, and a phosphate group. A phosphate group and an OH group are attached to 5’ position carbon and 3’ position carbon of the sugar molecule in a nucleotide, respectively. Nucleotides are joined together by phosphodiester bonds formed between 5’ phosphate group of one nucleotide and 3’ OH group of the adjacent nucleotide. If a polynucleotide chain has a free 5’ phosphate group, it is assigned as the 5’ end; if it has a free 3’ OH group, it is assigned as a 3’ end. Therefore, DNA strands usually have 5’ and 3’ ends according to the end positions of the polynucleotide chains. DNA also exists as double-stranded form. Two strands are antiparallel to each other. Therefore, DNA has two strands which run towards 5’ to 3’ direction and 3’ to 5’ direction. Upstream and downstream DNA is referred with reference to转录和5'至3’的合成mRNA链。If DNA is considered towards the 5 end of the编码链from the transcription initiation site it is known as upstream DNA. If DNA is considered towards the 3’ end from the coding strand from the transcription initiation site is known as downstream DNA。This is the key difference between upstream and downstream DNA.

内容
1.Overview and Key Difference
2.What is Upstream DNA
3.What is Downstream DNA
4.并排比较 - 上游与下游DNA
5.概括

What is Upstream DNA?

基因是一种结构nd functional unit heredity which is located on DNA of an organism. It is stored with instructions to construct a protein. The gene has a specific region of a DNA molecule. When required, it transcribes and translates into a protein via synthesis of anmRNA链。通常，基因的编码线从5'到3'方向运行。转录时，它会产生一个mRNA链，朝着5'至3’的相同方向。在转录期间，3'至5’antisense strand用作模板链并启动mRNA合成。基因中有一个转录启动位点。参考转录起始位点，朝编码链5'端的DNA区域称为上游DNA。该基因的启动子通常位于DNA的上游区域。在eukaryotic genes,there are TATA boxes, promoter proximal elements, and enhancers in the area upstream to the gene. The upstream region of the gene is referred with negative numbers. Upstream DNA of a gene is of utmost importance for the transcription.

什么是下游DNA？

Transcription initiation site is known as +1 point of a gene. The DNA region from +1 point towards the 3’ end of the coding strand is known as downstream DNA. In other words, downstream of the gene is from the transcription initiation site towards the 5’ end of thetemplate strand。因此，基因区域的下游DNA包括转录单元和其他序列，例如终结序列。启动子可以影响基因的下游序列。基因的下游部分被称为正数。基因的下游DNA是提供蛋白质产物的实际区域。

What is the difference between Upstream and Downstream DNA?

Upstream vs Downstream DNA
脱氧核糖核酸region towards the 5’ end of the coding sequence from the transcription initiation site is known as upstream DNA.	从转录启动位点朝着编码链的3'末端的DNA区域称为下游DNA。
Elements
启动子和增强剂位于上游DNA上	Transcription unit and the terminator sequences are located in the downstream DNA.
Numbering
上游区域中的核苷酸被称为负数	核苷酸被带有正数。
功能
该区域包含调节和启动转录所需的要素	该区域包含产生蛋白质并终止转录的指令

摘要 - 上游与下游DNA

It is easy to identify upstream and downstream of an RNA strand. With regard to the reference site, the region towards the 5’ end of the RNA strand is known as upstream RNA whereas region towards the 3’ end is known as downstream RNA. However, in DNA, there are two strands that run in both directions 5’ to 3’ and 3’ to 5’. Hence, the difference between upstream and downstream DNA is complicated. Therefore, it is differentiated with reference to the transcription of a gene. From the transcription initiation site towards the 5 end of the sense strand, DNA region is known as upstream DNA whereas from the transcription initiation site towards the 3’ end of the sense strand is known as downstream DNA. This is the difference between upstream and downstream of DNA.

参考：
1. Rhee, Amy C., Benjamin H. Somerlot, Neeta Parimi, and Jonatha M. Gott. “Distinct roles for sequences upstream of and downstream from Physarumediting sites.” RNA. Cold Spring Harbor Laboratory Press, Sept. 2009. Web. 18 Mar. 2017

Image Courtesy:
1. Barbosa，Cristina，Isabel Peixeiro和LuísaRomão。“基因表达通过上游开放式阅读框和人类疾病调节。”PLOS遗传学。公共科学图书馆网络。2017年3月18日。