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  • DNA is a molecule made up of two strands

    DNA是由兩股互相纏繞扭曲

  • twisted around each other in a double helix shape.

    形成的雙股螺旋分子

  • Each strand is made up a sequence of four chemical bases

    每一股是由四個化學鹼基形成的序列構成的

  • represented by the letters A, C, G and T.

    分別由字母A,C,G跟T表示

  • The two strands are complimentary.

    DNA兩股是互補的

  • This means that wherever there's a T in one strand

    意思是只要在其中一股上有一個T鹼基

  • there will be in an A in the opposite strand,

    另一股上就會有一個A鹼基與其配對

  • and wherever there's a C

    或者任一地方有C鹼基

  • there will be a G in the other strand.

    另一股上就會有G鹼基與其配對

  • Each strand has a 5' end and a 3' end.

    每一股可分為5'端與3'端

  • The two strands run in opposite directions.

    兩股的方向相反

  • This determines how each strand of DNA is replicated.

    這決定了兩股DNA會如何被複製

  • The first step in DNA replication is to separate the two strands.

    DNA複製的第一步是將兩股分開

  • This unzipping is done by an enzyme called helicase

    這個分開兩股的任務是由叫做解旋酶的酵素負責

  • and results in the formation of a replication fork.

    並且造成複製叉的形成

  • The separated strands each provide a template for creating a new strand of DNA.

    被分開的兩股各自提供了製造新股DNA的模板

  • An enzyme called primase starts the process.

    名為引子酶的酵素開始了複製的過程

  • This enzyme makes a small piece of RNA

    這個酵素製造了小片段的RNA

  • called a primer.

    稱作引子

  • This marks the starting point for the construction of the new strand of DNA.

    引子標記了新股DNA在何處開始被製造

  • An enzyme called DNA polymerase binds to the primer

    名為DNA聚合酶的酵素接上引子

  • and will make the new strand of DNA.

    並且製造DNA的新股

  • DNA polymerase can only add DNA bases in one direction,

    DNA聚合酶只能往一個方向加上DNA的鹼基

  • from the 5' end to the 3' end.

    即從5'端至3'端

  • One of the new strands of DNA, the leading strand,

    其中一股新股DNA,稱作領先股

  • is made continuously,

    能被不間斷的製造

  • the DNA polymerase adding bases one by one in the 5' to 3' direction.

    DNA聚合酶由5'至3'一個接一個的添加新的鹼基

  • The other strand, the lagging strand, cannot be made in this continuous way

    另外一股,稱作延遲股,無法如領先股一樣不間段的製造

  • because it runs in the opposite direction

    因為它的方向與領先股相反

  • the DNA polymerase can therefore only make this strand in a series of small chunks

    因此DNA聚合酶只能夠將延遲股的DNA做成一連串的短片段

  • called Okazaki fragments.

    稱作岡崎片段

  • Each fragment is started with an RNA primer.

    每一個片段由RNA引子起頭

  • DNA polymerase then adds a short row of DNA bases

    接著是被DNA聚合酶由5'端至3'端加上得

  • in the 5' to 3' direction.

    短片段的DNA鹼基

  • The next primer is then added further down the lagging strand.

    下一個引子接著在遠處被接上延遲股

  • Another Okazaki fragment is then made and the process is repeated again.

    接著另一段岡崎片段會被製造,並且一再重複這個過程

  • Once the new DNA has been made

    一旦新的DNA完成製作

  • the enzyme exonuclease removes all the RNA primers from both strands of DNA.

    會由核酸外切酶移除兩股DNA上的RNA引子

  • Another DNA polymerase enzyme then fills in the gaps that are left behind

    另一個DNA聚合酶接著將留下來的空隙

  • with DNA.

    補上DNA

  • Finally the enzyme DNA ligase seals up the fragments of DNA

    最後由DNA連接酶串聯起

  • in both strands to form a continuous double strand.

    在兩股中所有的片段並且形成連續的兩股

  • DNA replication is described as semi- conservative

    DNA複製被形容成半保留複製

  • because each DNA molecule is made up of one old, conserved strand of DNA

    是因為每個雙股DNA分子是由一股舊股,即被保留的DNA舊股

  • and one new one.

    與新股所組成

DNA is a molecule made up of two strands

DNA是由兩股互相纏繞扭曲

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B2 中高級 中文 英國腔 複製 片段 製造 酵素 形成 分開

用3D呈現DNA複製過程 (DNA replication - 3D)

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    申欣瑩 發佈於 2016 年 11 月 08 日
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