Biology 2581B Study Guide - Zygote, Chromosome Segregation, Meiosis

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21: transposable elements & variations in chromosome number. Barbara mcclintock was the first person who really described transposable elements or. Jumping genes that move from one place to another in the genome. Transposable elements are not just limited to maize, but exist in many organisms including mammals, insects, plants, and even some bacteria. Transposable elements can be classified into two major classes: retrotransposons/retroposons ( jump by using an rna intermediate) and transposons (transpose dna directly without and rna intermediate). There are many different types of transposable elements and they range from 50 base-pairs to 10 kilobase-pairs in length. Depending on the type of transposable element and the organism, there can be one to hundreds of thousands of transposable elements present in a given genome. About 45% of the human genome is composed of sequences that derive from transposable elements. Most of this percentage is comprised of retrotransposon groups non-long terminal.