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11.2 Gene Expression and Development

11.2 Gene Expression and Development. Essential Question: How does gene expression affect the development of an organism?. Standards. B-4.1 Compare DNA and RNA in terms of structure, nucleotides, and base pairs .

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11.2 Gene Expression and Development

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  1. 11.2 Gene Expression and Development Essential Question: How does gene expression affect the development of an organism?

  2. Standards • B-4.1 Compare DNA and RNA in terms of structure, nucleotides, and base pairs. • B-4.4 Summarize the basic processes involved in protein synthesis (including transcription and translation). • B-4.8 Compare the consequences of mutations in body cells with those in gametes.

  3. Objectives: • Explain the relationship between gene expression and morphogenesis. • Describe the influence of homeotic genes on Drosophila development. • Summarize the role of the homeobox in eukaryotic development. • Compare and contrast the roles of oncogenes and tumor-suppression genes.

  4. Relationship Between Gene Expression and Morphogenesis • All multicellular sexually reproducing organisms begin life as a fertilized egg, or zygote. • Although, every cell in the developing zygote contains the same genes, only a fraction of those genes are expressed. • Homeotic genes are master genes that determine overall body organization of multicellular organisms.

  5. Relationship Between Gene Expression and Morphogenesis • When a homeotic gene is translated, regulatory proteins are formed. • It is thought that these proteins regulate development by switching the genes that control development on or off. • Certain genes are turned on and off as various proteins are needed at different times during the organisms life.

  6. Relationship Between Gene Expression and Morphogenesis • Cell differentiation involves the development of cells with a specialized function. • As organisms grow and develop, organs and tissues develop into characteristic forms. • This development of form in an organism is called morphogenesis.

  7. Role of Homeotic Genes in Morphogenesis • Genes that regulate where certain anatomical structures, such as appendages, will develop are called homeoticgenes. • Pattern formation is essential to the development of all organisms. • Once the basic pattern of a developing organism has been established, homeotic genes tell each segment what to develop into.

  8. Homeotic genes are master genes that determine overall body organization of multicellular organisms. • Studies of the fruit fly, Drosophila, have shown scientists how these genes behave. • Each homeotic gene of Drosophila shares a common DNA sequence of approximately 180 nucleotide pairs. • This specific DNA sequence within a homeotic gene is called a homeobox. • Homeoboxes regulate patterns of development in the fruit fly.

  9. Role of the Homeobox in Eukaryotic Development • Recent research has demonstrated that this sequence is present in almost all eukaryotes. • The widespread presence of the homeobox implies that the homeobox may have evolved from a single gene in an ancient organism. • The homeobox is believed to regulate the expression of other genes and to play a major role in controlling developmental processes.

  10. Influence of Homeotic Genes on Drosophila Development • Mutations in homeotic genes have given scientists insight into how these genes work. • One such mutation is the antennapedia mutation in Drosophila. • This drastic mutation causes legs to grow in the place where antennae are normally found.

  11. Key Characteristics of Cancer • A tumor is any abnormal growth of cells that results from uncontrolled cell division. • Benign tumors remain in a generalized mass. They usually do not pose a threat. • Examples are warts, fibroid cysts • Malignant tumors (cancer) invade and destroy healthy tissues elsewhere in the body. • Metastasis is the term that describes the spread of cancer to other parts of the body.

  12. Kinds of Cancer • Sarcomas - grow in bone and muscle tissue

  13. Kinds of Cancer • Carcinomas - cancer of skin and tissues that line the organs of the body.

  14. Kinds of Cancer • Lymphomas - solid tumors that grow in tissues that form blood cells. • Leukemia - uncontrolled production of white blood cells.

  15. Causes of Cancer • Mutations that alter the expression of genes that code for growth factor proteins can lead to cancer.Mutagens are factors that cause mutations to occur in the cell. Most mutagens are carcinogens. • Exposure to carcinogens increase the risk of cancer.Carcinogens are cancer causing agents. • Tobacco • Asbestos • Ultraviolet radiation from the sun

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