BIOL 111 1st Edition Lecture 15 Outline of Last Lecture I. Section IV Review: Molecular BiologyII. The Central DogmaIII. The genetic codeIV. Self quizV. Transcription—making mRNAVI. Synthesis of transcriptionVII. Processing RNA in the nucleusVIII. Consequences of RNA splicingOutline of Current Lecture I. Introduction II. Cell communication and signalingIII. Steps of signal transduction pathwayIV. Regulating gene expressionV. How do these components work together to activate genesVI. Why are cell-type specific TFs necessary?VII. Cell-specific gene activationCurrent Lecture- Introductiono What is gene regulation? Turns genes on or of Location, timing, amounto Why do genes need to be regulated?- Cell communication and signalingo Sources of signals: local and long-distanceo Types of signals: protein, lipid, ion, carbohydrate Highly conserved—evidence for evolutionary relatednesso Paracrine signal is a signal that is produced in one cell, secreted in that cell and its target is a neighboring cello Synaptic signaling-a signal is produced from one cell and is sent through a neurotransmitter to afect another cell and stimulate ito Endocrine signaling-the producing cell is located a long way from the secreting cell, signal goes through the bloodstream- Steps fo signal transduction pathwayo Reception External signal binds receptor protieno Transduction Relay molecules in a signal transduction pathway Receptor protien altered, activates signal pathwayo Reception- Regulating gene expressiono Chromatin structure Review structure (Fig 16.21) 8 histone protiens + DNA = nucleosome- Histone modifications (to tails) (Fig 18.7)o Add acetyl groups to looseno Add methyl groups (-CH3) to condense- DNA modifications (methylation of genes)o Add methyl groups to specific baseso Usually inactivates geneso Patterns inherited in all descendent cellso Examples: Barr bodies, genomic imprintingo 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 + intronso 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 geneso Specific TFs/activator protiens DNA binding domain—enhancer Activation domain—mediatorso General TFs DNA binding domain—promoter Activation domain—mediators, RNA polymeraseo DNA bending protien- Why are cell-type specific TFs necessary?o Genomic equivalenceo Diferential gene expression- Cell-specific gene activationo Ex. Liver cell gene-albumin, eye lens cell gene-crystalline In liver cells In lens
View Full Document
Unlocking...