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Chapter 11 The Control of Gene Expression Key Terms activators adult stem cells alternative RNA splicing carcinogens clone differentiation embryonic stem cells (ES cells) enhancers gene expression histones homeoboxes homeotic gene nuclear transplantation nucleosome oncogene Word Roots trans- 5 across (signal-transduction pathway: the process by which a signal on a cell’s surface is converted into a specific cellular response inside the cell) What are some potential uses for cloning? What are the health problems associated with cloned animals? 11.1 Proteins interacting with DNA turn prokaryotic genes on or off in response to

environmental changes What is gene regulation and why is it important to an organism?

operator operon promoter proto-oncogene regeneration regulatory gene repressor reproductive cloning signal transduction pathway silencers therapeutic cloning transcription factors tumor-suppressor genes X chromosome inactivation

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What is the normal status of the lac operon? (Hint: Is there normally lactose around? Does it make sense to make lactase if there is not lactose present?) The lac operon is an inducible operon. If lactose is present in the environment, what happens? Label the following diagram Describe what is happening in your own words. What turns off this process? What is the normal status of the trp operon? (Hint: does it make sense to make tryptophan if there is some in the environment already?) The trp operon is a repressible operon. If there is tryptophan in the environment, what happens?

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11.2 Differentiation yields a variety of cell types, each expressing a different combination of genes

What is differentiation? How can there be so many types of cells yet they all use the same DNA? 11.3 Differentiated cells may retain all of their genetic potential What does the carrot experiment prove about differentiation? How is regeneration possible? 11.4 DNA packing in eukaryotic chromosomes helps regulate gene expression Describe how the DNA gets so tightly coiled or packed. How does packing prevent gene expression? 11.5 In female mammals, one X chromosome is inactive in each cell Explain what happens during X chromosome inactivation. What causes the tortoiseshell pattern in those cats?

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11.6 Complex assemblies of proteins control eukaryotic transcription Why is the default for most eukaryotic genes “off”? How do transcription factors help the RNA polymerase initiate transcription? How do genes that work together but are not located on the same chromosome coordinate their transciption? 11.7 Eukaryotic RNA may be spliced in more than one way How is it possible to get more than one polypeptide from the same gene? 11.8 Translation and later stages of gene expression are also subject to regulation How does the length of life of mRNA regulate protein production in the cytoplasm? Even though a protein is transcribed, it may not be functional yet. How is this accomplished in eukaryotes? How does the length of life of a protein provide regulation? 11.9 Review: multiple mechanisms regulate gene expression in eukaryotes Label the diagram which shows the process of gene expression from chromosome to protein. Make note of all the control points.

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Additional notes here:

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11.10 Nuclear transplantation can be used to clone animals How does nuclear transplantation create a clone? What is the goal of reproductive cloning? What is the goal of therapeutic cloning? 11.11Reproductive cloning has valuable applications, but human reproductive cloning

raises ethical issues Describe some ways that cloning of animals is being used today. What are the practical limitations of human cloning? What are the ethical implications of human cloning? 11.12 Therapeutic cloning can produce stem cells with great medical potential How can embryonic stem cells become any other cell? How can adult stem cells become other types of cells? What effect would therapeutic cloning have on the transplant process?

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11.13 Cascades of gene expression and cell-to-cell signaling direct the development of an animal

How does location determine the fate of cells in the fruitfly? What are homeotic genes and what is their importance in a developing embryo? 11.14 Signal transduction pathways convert messages received at the cell surface to

responses within the cell What is a signal transduction pathway? Label the following diagram and describe what is happening at each step.

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11.15 Key developmental genes are very ancient What are homeoboxes? What is the pattern comparing the mouse and the fruitfly homeotic genes? What is the evolutionary significance of homeotic genes? How do homeotic genes illustrate unity in diversity? 11.16 Cancer results from mutations in genes that control cell division How do viruses cause cancer? What is an oncogene and where do they come from? How can normal gene expression be changed and result in excessive cell growth (cancer)? What are tumor-suppressor genes supposed to do and what happens if the don’t do it?

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11.17 Oncogene proteins and faulty tumor-suppressor proteins can interfere with normal signal transduction pathways

Describe how a mutation in a proto-oncogene results in excessive cell division. Describe how a mutation in a tumor-suppressor gene results in excessive cell division. 11.18 Multiple genetic changes underlie the development of cancer Describe how colon cancer develops. Why do cancers take a long time to develop? 11.19 Mary-Claire King discusses mutations that cause breast cancer Why is it true that all cancer is a “genetic disease”? What is the difference between a somatic mutation and a germ-line mutation? What has Dr. King learned about the BRCA1 gene?

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11.20 Avoiding carcinogens can reduce the risk of cancer Describe the dangers of the following carcinogens: X-rays UV radiation Tobacco How can changes to you diet decrease your risk of cancer? Give some examples.