DevelopmentW2010.Lecture2notes - Development BIO 120 Winter...

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Development BIO 120 Winter 2010 Jeremy Lee Eva Murdock Patrick Yuh Lecture 2 Genetic Basis of Development I. Differential Gene Expression as the major feature of development. Major concepts underlying differential gene expression: a. Genomic equivalence : All cells in an organism contain the same complement of genes. These are the same set of genes that are established in the fertilized egg. b. Genes that are not utilized in differentiated cells are not mutated or destroyed; they can, in theory, still be expressed. 1. This concept, along with genomic equivalence, implies that, in theory, some cells could be totipotent i.e. they could still differentiate into all the different cells of the body. 2. In theory, some cells might not be totipotent but could be pluripotent , i.e. have limited abilities to differentiate but still retain the capacity to develop into two or more other types of cells. c. Only a small subset of the genome is expressed in any differentiated cell. II. Experiments demonstrating genomic equivalence, totipotency, pluripotency a. Metaplasia: the transformation of one type of differentiated cell into another type of differentiated cell. Example: Experimental regeneration of complete newt lens by cells of the iris (Fig. #1.) This is consistent with the concepts of genomic equivalence and pluripotency. b. Nuclear transplantation experiments. (Fig. #2) 1. Initial experiments (King and Briggs) in amphibians indicated that normal development proceeded when nuclei from early stage embryos or from tadpole germ cell nuclei were transplanted into an enucleated oocyte (i.e. egg in which the nucleus was removed.) (Fig. #3). Injecting nuclei from somatic cells of later stages into the
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This note was uploaded on 03/30/2010 for the course BIOLOGY 125 taught by Professor Jeremylee during the Winter '10 term at UCSC.

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DevelopmentW2010.Lecture2notes - Development BIO 120 Winter...

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