Transcription: Advanced Look --> 1.) DNA & TFIID

Before transcription of the DNA molecule can begin, certain factors must be present. These factors are responsible for altering the DNA in preparation for the actual transcription. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

To see the Quicktime movie for the following sequence of images, click here.

	Transcription begins with a strand of DNA. This simplified DNA model has been color-coded to show regions with important roles in transcription.
	The largest key region is the transcription unit.
	Upstream of the transcription unit is the TATA-box, a smaller section that helps to position the complexes involved in transcription.
	The final high-lighted region is the enhancer.
	TFIID, a general transcription factor, is shown approaching the strand of DNA.
	TFIID is the largest of the general transcription factors involved in eukaryotic transcription. The yellow part of the complex is called TBP.
	TBP (yellow) binds to the DNA, using the TATA-box to position itself near the iniation site of transcription.
	When the TBP portion of the TFIID molecule attaches to the TATA-box, its shape causes the DNA to bend.

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