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DNA Replication. Everything need energy to work properly!. . Transcription. . Transcription
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1. DNA Replication versus Transcription Lecture 8
16. Transcription
17. Transcription Copying DNA into RNA
19. Sigma Factors The initiation of transcription is an especially important step in gene expression because it is the main point at which the cell regulates which proteins are to be produced and at what rate. Bacterial RNA polymerase is a multisubunit complex. A detachable subunit, called sigma (s) factor, is largely responsible for its ability to read the signals in the DNA that tell it where to begin transcribing. RNA polymerase molecules adhere only weakly to the bacterial DNA when they collide with it, and a polymerase molecule typically slides rapidly along the long DNA molecule until it dissociates again. However, when the polymerase slides into a region on the DNA double helix called a promoter, a special sequence of nucleotides indicating the starting point for RNA synthesis, it binds tightly to it. The polymerase, using its s factor, recognizes this DNA sequence by making specific contacts with the portions of the bases that are exposed on the outside of the helix.
22. Transcription Copying DNA into RNA
