What is the lac operon? How is it controlled? QOD
Section 11-1 Control of Gene Expression
Gene Expression Only some genes are expressed at any given time Only some genes are expressed at any given time Cell specializationCell specialization Two steps: Two steps: Transcription – regulatory sitesTranscription – regulatory sites TranslationTranslation
The Lac Operon Jacob and Monod Jacob and Monod Studied gene expression in lac operon of E. Coli Studied gene expression in lac operon of E. Coli Structural genesStructural genes PromoterPromoter OperatorOperator OperonOperon
Controlling the Lac Operon Repression Repression Repressor proteinRepressor protein Regulator geneRegulator gene Activation Activation InducerInducer
Gene Expression in Eukaryotes Challenges: Challenges: Larger genomeLarger genome Several chromosomesSeveral chromosomes Specialized cellsSpecialized cells No operonsNo operons
How are genes controlled in eukaryotic organisms? QOD
Structure of Eukaryotic Genes Control before and after transcription Control before and after transcription DNA is coiled – affects gene expression DNA is coiled – affects gene expression EuchromatinEuchromatin HeterochromatinHeterochromatin Introns-Exons Introns-Exons Options for producing different proteinsOptions for producing different proteins Role for introns?Role for introns?
More on expression Control after transcription Control after transcription LocationsLocations Pre-mRNAPre-mRNA Splicing mRNA exons – Spliceosomes Splicing mRNA exons – Spliceosomes Alternative splicing Alternative splicing RNA as enzymes – ribozymes RNA as enzymes – ribozymes Enhancer control Enhancer control Enhancer regionEnhancer region Transcription factorsTranscription factors
Chapter 11 Removal of Introns After Transcription Section 1 Control of Gene Expression
Chapter 11 Controlling Transcription in Eukaryotes Section 1 Control of Gene Expression
How do complex multicellular organisms develop from an embryo? QOD
Section 11-2 Gene Expression and Development
Cell Differentiation Morphogenesis Morphogenesis Homeotic (Hox) genes Homeotic (Hox) genes Homeobox – 180 base pairsHomeobox – 180 base pairs Regulatory proteins – turn genes on/off Regulatory proteins – turn genes on/off Similar sequences found in many eukaryotic organisms Similar sequences found in many eukaryotic organisms
Cancer Tumor Tumor Benign tumorBenign tumor Malignant tumorMalignant tumor Types Types CarcinomasCarcinomas SarcomasSarcomas LymphomasLymphomas LeukemiaLeukemia
The Cell Cycle Normal – Cell needs: Normal – Cell needs: Adequate nutritionAdequate nutrition Attached to other cells, membrane, fibersAttached to other cells, membrane, fibers Stop dividing when become crowdedStop dividing when become crowded Cancer-causing Agents Cancer-causing Agents Growth factors and mutationsGrowth factors and mutations CarcinogensCarcinogens MutagensMutagens
More Causes More Causes Genetic factorsGenetic factors Environmental factorsEnvironmental factors Cigarette smoke Cigarette smoke Air and water pollution Air and water pollution UV radiation UV radiation Viral infection Viral infection Prevention Prevention Dietary methodsDietary methods Behavior modificationBehavior modification
More on Causes: Genes Oncogenes/Proto-oncogenes Oncogenes/Proto-oncogenes Tumor-suppressor genes Tumor-suppressor genes See Fig , p. 214See Fig , p. 214 Viruses Viruses
Chapter 11 Effect of Mutation on Gene Expression Section 2 Gene Expression in Development and Cell Division
Fig. 3.23
Stem Cells - Properties Undifferentiated (unspecialized) cells Undifferentiated (unspecialized) cells Differentiate to any type of cell based on signalsDifferentiate to any type of cell based on signals Depending on potency Depending on potency Self-renewing Self-renewing Mitosis differentiated cell + another stem cellMitosis differentiated cell + another stem cell
Potency of Stem Cells Totipotent Totipotent ZygoteZygote Pluripotent Pluripotent EmbryonicEmbryonic Multipotent Multipotent AdultAdult
Sources of stem cells Embryonic Embryonic From blastula stage of developing embryo (within first approx. 2 weeks)From blastula stage of developing embryo (within first approx. 2 weeks) PluripotentPluripotent Adult Adult Only in certain tissues (Brain, Bone marrow)Only in certain tissues (Brain, Bone marrow) MultipotentMultipotent Induced Pluripotent Stem Cells (IPS) Induced Pluripotent Stem Cells (IPS) Somatic cell PluripotentSomatic cell Pluripotent
Uses and Hurdles Potential Uses: Potential Uses: Cure diseasesCure diseases Repair spinal injuries/brain injuriesRepair spinal injuries/brain injuries Cloning organsCloning organs Hurdles: Hurdles: SignalsSignals Turning genes on/off is essential Turning genes on/off is essential CulturingCulturing Maintaining linesMaintaining lines Moral/Ethical debateMoral/Ethical debate