tailieunhanh - Lecture Biology - Chapter 16: Control of gene expression

In this chapter, students will be able to: Understand how regulatory proteins work and why gene control is necessary for a cell’s survival; differentiate between transcriptional and post-transcriptional control of gene regulation; know how RNA polymerase is linked to control of transcription; list the four primary kinds of structural motifs and delineate their modes of action;. | Control of Gene Expression Chapter 16 Control of Gene Expression Controlling gene expression is often accomplished by controlling transcription initiation. Regulatory proteins bind to DNA to either block or stimulate transcription, depending on how they interact with RNA polymerase. Control of Gene Expression Prokaryotic organisms regulate gene expression in response to their environment. Eukaryotic cells regulate gene expression to maintain homeostasis in the organism. Regulatory Proteins Gene expression is often controlled by regulatory proteins binding to specific DNA sequences. regulatory proteins gain access to the bases of DNA at the major groove regulatory proteins possess DNA-binding motifs Regulatory Proteins DNA-binding motifs are regions of regulatory proteins which bind to DNA helix-turn-helix motif homeodomain motif zinc finger motif leucine zipper motif Helix-Turn-Helix Motif Homeodomain Motif Zinc Finger Motif Leucine Zipper Motif Prokaryotic Regulation Control of transcription initiation can be: positive control – increases transcription when activators bind DNA negative control – reduces transcription when repressors bind to DNA regulatory regions called operators Prokaryotic Regulation Prokaryotic cells often respond to their environment by changes in gene expression. Genes involved in the same metabolic pathway are organized in operons. Some operons are induced when the metabolic pathway is needed. Some operons are repressed when the metabolic pathway is no longer needed. Prokaryotic Regulation The lac operon contains genes for the use of lactose as an energy source. Regulatory regions of the operon include the CAP binding site, promoter, and the operator. The coding region contains genes for 3 enzymes: b-galactosidase, permease, and transacetylase Prokaryotic Regulation The lac operon is negatively regulated by a repressor protein: lac repressor binds to the operator to block transcription in the . | Control of Gene Expression Chapter 16 Control of Gene Expression Controlling gene expression is often accomplished by controlling transcription initiation. Regulatory proteins bind to DNA to either block or stimulate transcription, depending on how they interact with RNA polymerase. Control of Gene Expression Prokaryotic organisms regulate gene expression in response to their environment. Eukaryotic cells regulate gene expression to maintain homeostasis in the organism. Regulatory Proteins Gene expression is often controlled by regulatory proteins binding to specific DNA sequences. regulatory proteins gain access to the bases of DNA at the major groove regulatory proteins possess DNA-binding motifs Regulatory Proteins DNA-binding motifs are regions of regulatory proteins which bind to DNA helix-turn-helix motif homeodomain motif zinc finger motif leucine zipper motif Helix-Turn-Helix Motif Homeodomain Motif Zinc Finger Motif Leucine Zipper Motif .