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Regulation of Gene Activity and Gene Mutations. Mader - Chapter 15. Prokaryotic Regulation. The Operon Model Structural genes are controlled by upstream operator DNA than can bind a repressor molecule which prohibits RNA polymerase from binding to the promoter region of DNA.
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Regulation of Gene Activity and Gene Mutations Mader- Chapter 15
Prokaryotic Regulation • The Operon Model • Structural genes are controlled by upstream operator DNA than can bind a repressor molecule which prohibits RNA polymerase from binding to the promoter region of DNA
Repressible vs. Inducible Operons trpOperon • Repressible operon • The gene for anabolizing tryptophan is turned off in the presence of the amino acid tryptophan lacOperon • Inducible operon • The gene for catabolizing lactose is turned on in the presence of the sugar lactose Virtual Cell lacOperon Movie
Eukaryotic Regulation 5 Levels of Eukaryotic Gene Regulation • Chromatin Structure-Does RNA Polymerase have access to the gene • Transcriptional Control-transcription factors, activators, and the presence or absence of transposons • Posttranscriptional Control-RNA processing • Translational Control- Does tranlation take place and for how long? • Post Translational Control- Activation of the protein itself
One of my X chromosomes is shut down through methylation in every cell… meow! Chromatin Structure Acetylation (-COCH3) opens up the DNA for transcription but Methylation (-CH3) of the tails shuts it down
Transcriptional Control in Eukaryotes • Transcription Factors and Activators • Transcription Factors- There are many types… these proteins bind to the promoter and help RNA polymerase bind • Transcription Activators- bind to an upstream Enhancer region and also promote transcription Transposons “Jumping Genes” are noncoding sections of DNA that can also insert themselves into the structural gene and effectivly turn them off
Post Transcriptional Control- mRNA Editing It is not well understood how cells determine which form of mature mRNA that they will make