Biology 2581B Lecture Notes - Lecture 21: Copia (Museum), Polytene Chromosome, Genome Size
19 Feb 2018
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Lecture 21: transposable elements & variations in chromosome numbers. Tes move from one position in the genome to another. Tes are found in all organisms: from bacteria to humans to insects. First evidence by marcus roades in 1930s: very controversial topic back in the day. Some with cool names: mariner, gypsy, looper, springer, hopper, stalker, invader, diver, frogger. Can be 50 bp to 10 kb in length. Different copy numbers: one to 100 thousands. Selfish : carrying only information that allows their self-perpetuation. Self-perpetuation, i. e. carries info that it requires to jump. Tes do not depend on host systems to jump : however, there are examples where tes have functions in the host. Transpose via reverse transcription of an rna intermediate. Transpose dna directly without an rna intermediate. ~ 45% of the total genome: not all of it is active. 300000 copies, 0. 28 kb (comprises a lot less of genome b/c short interspersed nuclear elements)
