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What is the lac operon? How is it controlled?

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 Cell specialization Two steps: Transcription – regulatory sites Translation. The Lac Operon. Jacob and Monod

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What is the lac operon? How is it controlled?

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  1. What is the lac operon? How is it controlled? QOD

  2. Section 11-1 Control of Gene Expression

  3. Gene Expression • Only some genes are expressed at any given time • Cell specialization • Two steps: • Transcription – regulatory sites • Translation

  4. The Lac Operon • Jacob and Monod • Studied gene expression in lac operon of E. Coli • Structural genes • Promoter • Operator • Operon

  5. Controlling the Lac Operon • Repression • Repressor protein • Regulator gene • Activation • Inducer

  6. Gene Expression in Eukaryotes • Challenges: • Larger genome • Several chromosomes • Specialized cells • No operons

  7. How are genes controlled in eukaryotic organisms? QOD

  8. Structure of Eukaryotic Genes • Control before and after transcription • DNA is coiled – affects gene expression • Euchromatin • Heterochromatin • Introns-Exons • Options for producing different proteins • Role for introns?

  9. More on expression • Control after transcription • Locations • Pre-mRNA • Splicing mRNA exons – Spliceosomes • Alternative splicing • RNA as enzymes – ribozymes • Enhancer control • Enhancer region • Transcription factors

  10. Section 1 Control of Gene Expression Chapter 11 Removal of Introns After Transcription

  11. Section 1 Control of Gene Expression Chapter 11 Controlling Transcription in Eukaryotes

  12. How do complex multicellular organisms develop from an embryo? QOD

  13. Section 11-2 Gene Expression and Development

  14. Cell Differentiation • Morphogenesis • Homeotic (Hox) genes • Homeobox – 180 base pairs • Regulatory proteins – turn genes on/off • Similar sequences found in many eukaryotic organisms

  15. Cancer • Tumor • Benign tumor • Malignant tumor • Types • Carcinomas • Sarcomas • Lymphomas • Leukemia

  16. The Cell Cycle • Normal – Cell needs: • Adequate nutrition • Attached to other cells, membrane, fibers • Stop dividing when become crowded • Cancer-causing Agents • Growth factors and mutations • Carcinogens • Mutagens

  17. More Causes • Genetic factors • Environmental factors • Cigarette smoke • Air and water pollution • UV radiation • Viral infection • Prevention • Dietary methods • Behavior modification

  18. More on Causes: Genes • Oncogenes/Proto-oncogenes • Tumor-suppressor genes • See Fig. 11-10, p. 214 • Viruses

  19. Section 2 Gene Expression in Development and Cell Division Chapter 11 Effect of Mutation on Gene Expression

  20. Fig. 3.23

  21. Stem Cells - Properties • Undifferentiated (unspecialized) cells • Differentiate to any type of cell based on signals • Depending on potency • Self-renewing • Mitosis  differentiated cell + another stem cell

  22. Potency of Stem Cells • Totipotent • Zygote • Pluripotent • Embryonic • Multipotent • Adult

  23. Sources of stem cells • Embryonic • From blastula stage of developing embryo (within first approx. 2 weeks) • Pluripotent • Adult • Only in certain tissues (Brain, Bone marrow) • Multipotent • Induced Pluripotent Stem Cells (IPS) • Somatic cell  Pluripotent

  24. Uses and Hurdles • Potential Uses: • Cure diseases • Repair spinal injuries/brain injuries • Cloning organs • Hurdles: • Signals • Turning genes on/off is essential • Culturing • Maintaining lines • Moral/Ethical debate

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