Introduction to Genetic Analysis 426

Introduction to Genetic Analysis 426 - 44200_13_p423-450...

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425 13.1 Discovery of transposable elements in maize insertions of class 1 elements into the genome are essen- tially permanent. That is, they cannot be excised from the donor site. Nonetheless, they are still considered to be mobile because their copies can insert into new tar- get DNA. In contrast, class 2 elements are called DNA ele- ments because a class 2 element itself moves from one site in the genome to another. Unlike class 1 elements, class 2 elements can excise from the donor site, which means that, if insertion into a gene has created a muta- tion, excision of the element can lead to the reversion of the original mutation. The Frst transposable elements discovered genetically in maize were class 2 elements that led to unusual spotted kernels due to their excision from genes responsible for pigment production in the kernel. In their studies, scientists are able to exploit the ability of transposable elements to insert into new sites in the genome. Transposable elements engineered in the test tube are valuable tools, both in prokaryotes and in eukaryotes, for genetic mapping, creating mutants, cloning genes, and even producing transgenic organisms. Let us reconstruct some of the steps in the evolution of
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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