Transcription, Transcription Factors, and Chromatin Remodeling PDF
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This document provides an overview of transcription, transcription factors, and chromatin remodeling in eukaryotic genes. It describes the general features of a eukaryotic gene, the role of the genome in regulating genes, and the steps involved in transcription.
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Transcription, Transcription Factors, and Chromatin Remodeling The Gene Complex collection of sequences that o Controls a phenotype ▪ Individually OR ▪ Complexed with the action of other genes Size varies Structural f...
Transcription, Transcription Factors, and Chromatin Remodeling The Gene Complex collection of sequences that o Controls a phenotype ▪ Individually OR ▪ Complexed with the action of other genes Size varies Structural features vary Encode for a protein(s) that is translated from a mRNA Expression o Requires many associated factors The Genome Is Significantly Involved in Gene Regulation The number of promoter sequences is equal to the number of protein coding sequences Transcription regulation is a major function of the genome Transcription - the synthesis of RNA from a DNA template Three Main Transcription Events For prokaryotic or eukaryotic organisms 1. Initiation Binding of RNA polymerase to double-stranded DNA o This step involves a transition to single-strandedness in the region of binding ▪ RNA polymerase binds at a sequence of DNA generally called the promoter Initiation is the most important step in gene expression!!! 2. Elongation The covalent addition of nucleotides to the 3' end of the growing polynucleotide chain o Involves the development of a short stretch of DNA that is transiently single-stranded 3. Termination The recognition of the transcription termination sequence o Release of RNA polymerase 2 Product of Transcription Transcription Unit Extends from the transcription start site (TSS) to the termination sequence The product is called the o Primary Transcript ▪ Immediate transcription product Other Critical Sequences for Transcription Upstream Sequences o Sequences before the mRNA transcription start site o Necessary for building the transcription apparatus for transcription Downstream Sequences o Sequences after the start site o Can also have a regulatory effect Eukaryotic RNA Polymerase 1. Three types of RNA Polymerase exist Each with a distinct function Type of Polymerase Product Location Size Subunits RNA Polymerase I rRNA nucleolus 590 kDa 14 RNA Polymerase II hnRNA nucleoplasm 550 kDa 12 RNA Polymerase III tRNA nucleoplasm 700 kDa 17 2. RNA Polymerase II is key to mRNA synthesis ~550 kd in size Two large subunits
