The first thing you need to know is that transcription has nothing to do with cell replication processes such as DNA replication, mitosis, or cell division.

首先要知道的是，轉錄與 DNA 複製、有絲分裂或細胞分裂等細胞複製過程無關。

So, what is transcription and why is it necessary?

那麼，什麼是轉錄，為什麼需要轉錄？

Well, transcription is the first step in the process of using the genetic code in DNA to synthesize or build all the different proteins in your body.

轉錄是利用 DNA 中的遺傳密碼合成或構建體內所有不同蛋白質的第一步。

One problem with synthesizing these proteins is that the instructions for making them are in the DNA, which is located inside the nucleus.

合成這些蛋白質的一個問題是，製造它們的指令在 DNA 中，而 DNA 位於細胞核內。

But, the place proteins are always made is outside the nucleus, either in the ribosomes floating in the cytoplasm or in the ribosomes embedded in the rough endoplasmic reticulum.

但是，製造蛋白質的地方總是在細胞核之外，要麼是漂浮在細胞質中的核糖體，要麼是嵌入粗麵內質網中的核糖體。

So, how does the genetic code for synthesizing proteins get from the DNA to the ribosome?

那麼，合成蛋白質的遺傳密碼是如何從 DNA 傳到核糖體的呢？

DNA uses a messenger called messenger RNA or mRNA to carry the genetic code from the nucleus to the ribosome.

DNA 使用一種稱為信使 RNA 或 mRNA 的信使將遺傳密碼從細胞核傳遞到核糖體。

The process of building this messenger RNA is called transcription.

構建這種信使 RNA 的過程稱為轉錄。

Now, let's see how transcription happens.

現在，讓我們看看轉錄是如何進行的。

Transcription begins when an enzyme called RNA polymerase attaches to a segment of DNA called a gene.

當一種叫做 RNA 聚合酶的酶連接到一段叫做基因的 DNA 上時，轉錄就開始了。

A gene contains the code to build a specific protein, which is a macromolecule made up of a sequence of amino acids in a specific order.

基因包含構建特定蛋白質的代碼，蛋白質是由特定順序的氨基酸序列組成的大分子。

And within a gene, the specific order of nitrogenous bases dictates the order of amino acids that will make up the protein.

在一個基因中，含氮鹼基的特定順序決定了組成蛋白質的氨基酸的順序。

Each group of three consecutive bases in the gene is actually a code for a particular amino acid.

基因中每三個連續鹼基組實際上是一個特定氨基酸的代碼。

As a result, each group is referred to as a codon.

是以，每一組被稱為一個密碼子。

RNA polymerase causes a particular area of the DNA helix to unwind and separate into two strands.

RNA 聚合酶使 DNA 螺旋的一個特定區域解旋並分離成兩條鏈。

One of the strands, often called the template strand, is the side of DNA that is read or transcribed by the messenger RNA.

其中一條鏈通常被稱為模板鏈，是 DNA 被信使 RNA 讀取或轉錄的一側。

The other strand of DNA, often called the non-template strand, isn't transcribed by the messenger RNA.

DNA 的另一條鏈通常被稱為非模板鏈，它不會被信使 RNA 轉錄。

So, how are DNA instructions transcribed into messenger RNA?

那麼，DNA 指令是如何轉錄成信使 RNA 的？

Well, using the template strand as a guide, RNA polymerase uses the base-pair rule to assemble free nucleotides in the nucleus into a complementary strand of RNA.

那麼，以模板鏈為嚮導，RNA 聚合酶利用鹼基對規則將細胞核中的遊離核苷酸組裝成 RNA 的互補鏈。

For example, RNA polymerase reads the DNA base thymine on the template strand, then binds it to a free nucleotide containing adenine.

例如，RNA 聚合酶讀取模板鏈上的 DNA 鹼基胸腺嘧啶，然後將其與含有腺嘌呤的遊離核苷酸結合。

This process continues with cytosine binding to guanine and guanine binding with cytosine.

胞嘧啶與鳥嘌呤結合，鳥嘌呤與胞嘧啶結合，這一過程一直持續下去。

Remember, though, RNA will never contain thymine.

但請記住，RNA 永遠不會包含胸腺嘧啶。

So, whenever RNA polymerase sees adenine on the DNA template strand, it pairs adenine with uracil.

是以，只要 RNA 聚合酶在 DNA 模板鏈上看到腺嘌呤，它就會將腺嘌呤與尿嘧啶配對。

By using the template strand of DNA as a guide, the genetic code from the non-template strand of DNA has actually been transcribed into messenger RNA.

以 DNA 模板鏈為嚮導，DNA 非模板鏈上的遺傳密碼實際上已被轉錄為信使 RNA。

When transcription is complete, the messenger RNA, which is small enough to fit through a nuclear pore, takes the genetic code out of the nucleus to the ribosome, the site of protein synthesis.

轉錄完成後，小到足以穿過核孔的信使 RNA 將遺傳密碼帶出細胞核，進入蛋白質合成場所--核糖體。

The process of actually building the protein at the ribosome is called translation, which we'll cover in a separate video.

在核糖體上實際構建蛋白質的過程稱為翻譯，我們將在另一個視頻中介紹。

To summarize, transcription is the process of transcribing or copying the genetic code for building a protein into messenger RNA.

總而言之，轉錄是將構建蛋白質的遺傳密碼轉錄或複製到信使 RNA 中的過程。

A gene is a segment of DNA containing the instructions or code for building a protein.

基因是含有構建蛋白質的指令或代碼的 DNA 片段。

A codon is a group of three consecutive nitrogenous bases in a gene containing the code for a specific amino acid in a protein.

密碼子是基因中三個連續的含氮鹼基組，包含蛋白質中特定氨基酸的代碼。

RNA polymerase unwinds the strands of DNA in a gene.

RNA 聚合酶能解開基因中的 DNA 鏈。

The template DNA strand contains the complementary bases that need to be read to generate messenger RNA.

模板 DNA 鏈包含生成信使 RNA 所需的互補鹼基。

The base-pair rule is followed when assembling messenger RNA.

組裝信使 RNA 時遵循鹼基對規則。

Messenger RNA is actually a copy of the DNA non-template strand with uracil substituted for thymine.

信使核糖核酸實際上是用尿嘧啶取代胸腺嘧啶的 DNA 非模板鏈的拷貝。

Thanks for watching!

感謝觀看！