Chapter 11 - Chapter 11 Detailed Lecture Outline...

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Chapter 11 Detailed Lecture Outline Introduction To Clone or Not to Clone A. A clone is a genetically identical organism, which originated from a somatic cell nucleus of another organism. All the a B. There are a multitude of problems associated with cloning an organism, including rapid onset of “old age” and age-related illnesses of the cloned organism. C. Ethical and evolutionary issues are being raised with the ability to clone to curb the extinction of endangered species. D. This chapter describes the control of gene expression in prokaryotes and eukaryotes, methods and applications of animal cloning, the connections between embryonic development and gene regulation, and the genetic basis of cancer. I. Gene Regulation Module 11.1 Proteins interacting with DNA turn prokaryotic genes on or off in response to environmental changes. A. The process of turning on or turning off a gene is called gene regulation. Gene regulation or control allows an organism to respond quickly to changes in the environment. The flow of information from gene to protein is called gene expression. B. This model of gene control was first proposed as a hypothesis in 1961 by Jacob and Monod, for the control of lactose utilization enzymes in E. coli (Figure 11.1A). NOTE: Much experimental evidence has since confirmed the existence of this and other operons in many bacteria. C. Important features of the model: An operon consists of several DNA sequences coding for different enzymes, all involved in the same cellular process. Expression of the operon is controlled as a unit. Other DNA sequences in and near the operon control the operon’s expression. The presence or absence of the enzyme’s substrate turns on or off the controls. D. Operon expression normally starts with RNA polymerase binding at the promoter region (the first nongene region of the operon), moving along and transcribing each gene in the operon. E. When the lac operon is “turned off,” a regulatory gene is transcribed and translated into a repressor protein. The repressor protein binds with the operator region of the operon, repressing the transcription of the genes further along the operon (Figure 11.1B). Operators are located between the promoter and the utilization-genes for translation. F. When the lac operon is “turned on,” the regulatory gene continues to be transcribed and translated into repressor, but the presence of substrate (lactose) interferes with the binding of the repressor to the operator. This permits the expression of the remainder of the operon. Expression continues until the substrate is used up. Then the repressor is free to repress the operator, and the operon turns off as above (Figure 11.1B). G.
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This note was uploaded on 03/10/2011 for the course BIOL 10 taught by Professor Kite during the Spring '11 term at Laney College.

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Chapter 11 - Chapter 11 Detailed Lecture Outline...

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