BIOL 111 1st Edition Lecture 15 Outline of Last Lecture I Section IV Review Molecular Biology II The Central Dogma III The genetic code IV Self quiz V Transcription making mRNA VI Synthesis of transcription VII Processing RNA in the nucleus VIII Consequences of RNA splicing Outline of Current Lecture I Introduction II Cell communication and signaling III Steps of signal transduction pathway IV Regulating gene expression V How do these components work together to activate genes VI Why are cell type specific TFs necessary VII Cell specific gene activation Current Lecture Introduction o What is gene regulation Turns genes on or of Location timing amount o Why do genes need to be regulated Cell communication and signaling o Sources of signals local and long distance o Types of signals protein lipid ion carbohydrate Highly conserved evidence for evolutionary relatedness o Paracrine signal is a signal that is produced in one cell secreted in that cell and its target is a neighboring cell o Synaptic signaling a signal is produced from one cell and is sent through a neurotransmitter to afect another cell and stimulate it o Endocrine signaling the producing cell is located a long way from the secreting cell signal goes through the bloodstream Steps fo signal transduction pathway o Reception External signal binds receptor protien o Transduction Relay molecules in a signal transduction pathway Receptor protien altered activates signal pathway o Reception Regulating gene expression o Chromatin structure Review structure Fig 16 21 8 histone protiens DNA nucleosome Histone modifications to tails Fig 18 7 o Add acetyl groups to loosen o Add methyl groups CH3 to condense DNA modifications methylation of genes o Add methyl groups to specific bases o Usually inactivates genes o Patterns inherited in all descendent cells o Examples Barr bodies genomic imprinting o Regulation of transcription initiation Enhancer DNA sequence here cell type specific TFs bind Promoter DNA sequence where general TFs bind attracting RNA polymerase Termaination DNA sequence where RNA polymerase stops Pre RNA transcript exons introns o Post transcriptional regulation Alternative RNA splicing Regulatory proteins can bind introns and guide spliceosomes MRNA degradation lifespan varies depending on 5 cap and 3 UTR Translation inhibition Protiens bind to 5 UTR and 3 UTR to block ribosomes At appropriate time initiation factors promote growth of polyA tail and ribosomal binding Protein processing To be functional a protein may need to be chemically modified or cut smaller Protein degradation Protein lifespan can vary If tagged with ubiquitin protein is marked Proteasome complex seeks ubiquitin marked protiens and breaks them down How do these components work together to activate genes o Specific TFs activator protiens DNA binding domain enhancer Activation domain mediators o General TFs DNA binding domain promoter Activation domain mediators RNA polymerase o DNA bending protien Why are cell type specific TFs necessary o Genomic equivalence o Diferential gene expression Cell specific gene activation o Ex Liver cell gene albumin eye lens cell gene crystalline In liver cells In lens cells
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