字幕列表 影片播放
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Including,
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Transcription begins with a strand of DNA.
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It is divided into several important regions.
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The largest of these is the transcription unit.
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This portion of the DNA will be used to produce RNA.
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Upstream of the transcription unit is the TATA box.
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An enhancer region may also be involved.
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Several complexes, known as transcription factors,
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are required for successful transcription.
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The first is TFIID,
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the largest of the general factors.
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A component of this factor, TBP,
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binds to the DNA
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using the TATA box to position TFIID
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near the transcription initiation site.
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Other transcription factors,
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including TFIIA and TFIIB, then attach.
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These complexes prepare the DNA
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for the successful binding of RNA polymerase.
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Once RNA polymerase is bound,
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other transcription factors complete the mature transcription complex.
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Now, energy must be added to the system for transcription to begin.
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This energy is provided by the reduction of ATP
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into ADP and Pi.
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RNA polymerase then synthesizes an RNA template
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from the strand of DNA.
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Most factors are released after transcription begins.
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When the end of the transcription unit is reached,
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the RNA polymerase dissociates,
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and the newly formed strand of RNA is released.
