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Modeling of lac operon regulation Maxim Tikhonov
Goals Create model of lac operon regulation Investigate the origin of bistability.
Mechanistic diagram I I Lac I ex I I MR R R R2R2 R2R2 LacI MY Lac R2R2 R2R2 R2R2 R2R2 I I I I
ODEs: dMR/dt=k_sMR-l_MR*MR dR/dt=k_sR*MR-2*dimeris-l_R*R dR2/dt=dimeris-repres-inactiv-l_R2*R2 dO/dt=-repres+derepres dI/dt=-2e-3*inactiv-2e-3*derepres+1e-3*k_ft*YI+2e- 3*l_I2R2*I2R2+1e-3*l_YI*YI+dif dI2R2/dt=inactiv+derepres-l_I2R2*I2R2 dMY/dt=k_s0MY*(Otot-O)+k_s1MY*O-l_MY*MY dY/dt=k_sY*MY-binding-l_Y*Y dYI/dt=binding-l_YI*YI __________ dimeris=k_2R*R^2-k_r2R*R2 repres=k_r*R2*O-k_rr*(Otot-O) binding=-(k_ft+k_rp)*YI+k_p*Y*Iex*1000 inactiv=k_dr1*R2*I^2-k_rdr1*I2R2 derepres=k_dr2*(Otot-O)*I^2-k_rdr2*O*I2R2 dif=k_t*(Iex-I) MR – Repressor RNA R – repressor R2 – repressor dimer O - operon I – internal IPTG I2R2 – inactive repressor MY – permease RNA Y – permease YI – permease/IPTG complex
[Iex] was used as the main bifurcation parameter Within the range [Iex] = 24.2-32.4 uM, two branches of stable steady states exist, separated by branch of unstable steady states.
Conclusion Model of lac operon regulation was implemented. The system exhibits bistability within the range [Iex] = 24.2-32.4 uM
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 18.1: The trp operon.
Are genes always being transcribed and translated?
Central Dogma （中心法则） Reverse Transcription Adapted from:
Lecture 3: Models of gene regulation. DNA Replication RNA Protein TranscriptionTranslation.
Regulation of gene expression References: 1.Stryer: “Biochemistry”, 5 th Ed. 2.Hames & Hooper: “Instant Notes in Biochemistry”, 2 nd Ed.
LacZ lacY lacA OA i Repressor lactose lactose/repressor RNA pol CRP cAMP CRP/cAMP complex CAP complex B-galactosidase lactose permease transcetylase operator.
Bacterial Operons A model of gene expression regulation Ch 18.4.
The Lac Operon Regulation of Prokaryotic Genes. n Scientists investigated a transcriptionally regulation system using the lactose metabolism system in.
PROKARYOTE GENE REGULATION transcriptional control post-transcriptional control post-translational control REGULATION OF TRANSCRIPTION Negative Positive.
CONTROL MECHANISMS 5.5. Controlling Transcription and Translation of Genes Housekeeping Genes: needed at all times: needed for life functions vital.
Positive Feedback and Bistability BIOE 423: 2013.
Gene Regulation. Levels of Regulation DNA rearrangement –Immune System rearranges DNA Bacteria can change DNA in chromosomes Not as common as other methods.
Regulation of Gene Expression Prokaryotes and Eukaryotes.
Goal Show the modeling process used by both Collins (toggle switch) and Elowitz (repressilator) to inform design of biological network necessary to encode.
William S. Klug Michael R. Cummings Charlotte A. Spencer Concepts of Genetics Eighth Edition Chapter 16 Regulation of Gene Expression in Prokaryotes Copyright.
Controlling Gene Expression. Control Mechanisms Determine when to make more proteins and when to stop making more Cell has mechanisms to control transcription.
Control Mechanisms. Four Levels of Control of Gene Expression Type of ControlDescription Transcriptional Regulates which genes are transcribed. Controls.
Genetics NewsGenetics News Seminar Monday, Oct 30 John Ryan Immunology, asthma Printing problems.
Genetics NewsGenetics News F 1 completed last night P’s doing fine.
Gene Regulation Prokaryotes (no nucleus). Lac operon System of genes that can turn on and off in E. coli (bacteria). These genes make enzymes that break.
5.5 Control Mechanisms There are approximately genes that exist to code for proteins in humans. – Not all proteins are required at all times. –
Goals: Discuss 3 examples of transcriptional regulation -Lac operon -Coordinated gene regulation -Regulation of transcription without regulation of polymerase.
Chapter 10 The Operon Tsung-Luo Jinn. Gene expression controlled at: Transcription—initiation,termination, not elongation Processing—in EuK RNA splicing,
Gene Regulation. What is gene expression? Gene expression means the DNA has been turned into a protein (the gene has been turned on/expressed) Remember.
- George Bernard Shaw „Self Control is the quality that distinguishes the fittest to survive”
Complexities of Gene Expression Cells have regulated, complex systems –Not all genes are expressed in every cell –Many genes are not expressed all of.
Chapter 11 Molecular Mechanisms of Gene regulation Jones and Bartlett Publishers © 2005.
Prokaryotes vs Eukaryotes. II. RNA modification 5” cap chemically speaknig.
Negative regulatory proteins bind to operator sequences in the DNA and prevent or weaken RNA polymerase binding.
GENE EXPRESSION and the LAC OPERON We have about genes inside our DNA that code for proteins. Clearly not all the proteins are needed at the same.
Gene Regulation Gene Regulation in Prokaryotes – the Jacob-Monad Model Gene Regulation in Prokaryotes – the Jacob-Monad Model certain genes are transcribed.
Bistable and Oscillatory Systems. Bistable Systems Systems which display two stable steady states with a third unstable state are usually termed bistable.
Control of Transcription DNA has “on” and “off” switches Activator –protein that binds near gene’s promoter region - allows RNA polymerase to transcribe.
Genetic Regulatory Mechanisms. Inducible Genes - Operon Model Definition: Genes whose expression is turned on by the presence of some substance –Lactose.
PowerPoint Presentation Materials to accompany Genetics: Analysis and Principles Robert J. Brooker Copyright ©The McGraw-Hill Companies, Inc. Permission.
Chapter 21 (Part 2) Transcriptional Regulation and RNA Processing.
Control of Gene Expression Chapter DNA RNA Protein replication (mutation!) transcription translation (nucleotides) (amino acids) (nucleotides) Nucleic.
1. What does the phrase “gene regulation” mean? 2. If the lac operon cannot bind to the repressor.. What would be the outcome? (Assume E. Coli) 3.
Chapter 16 – Control of Gene Expression in Prokaryotes.
The Lac Operon An operon is a length of DNA, made up of structural genes and control sites. The structural genes code for proteins, such as enzymes.
Prokaryotic Regulation Regulation of Gene Expression – Part I Spring Althoff Reference: Mader & Windelspecht Ch. 13) Lec 18.
Biology Chapter 12 Section 5 Gene Regulation. Objectives ______________a typical gene _________how lac genes are turned off and on __________how most.
Prokaryotic Gene Regulation April 22, 2015 Richard D. Howells, PhD MSB E-643
Gene regulation. Gene expression models Prokaryotes and Eukaryotes employ common and different methods of gene regulation Prokaryotic models 1. Trp.
The Chapter 15 Homework is due on Wednesday, February 4 th at 11:59 pm.
Lac Operon & Mutants. lac Operon lacZlacYlacAoCAPplacI β-galactosidase, 3.1 kb mRNA, 120 kD (1)glc-gal glc + gal (2)β-1-4 lactose β-1-4 allolactose.
The need for gene regulation Bacterial genome4,000 genes Human genome100,000 genes Not all expressed at any one time May need very high levels e.g. translation.
Protein Synthesis Control Mechanisms. Control Mechansisms the human genome contains about genes that code for proteins housekeeping genes.
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