Transposon
Transposon Are the group of mobile genetic element
that are define as a DNA sequence . Trans. Can jump into different places of the genome for this
reason they are called jumping gene. They are divided in to two main groups-
i) Retro transposon ii) DNA transposon
Trasposon in bacteria:
There are two main types of transposable
elements in bacteria having diff siz and
structure.
1. Insertion sequence (IS) elements.
2.
Prokaryotic transposon Tn - composite and non composite transposons.
1. . Insertion sequence (IS)-
2. Prokaryotic transposon -
Transposon in human
Transposon in human are in the form of repetitive DNA which consists of sequence that are interspersed within the entire human genome. This sequence are transposable and can move to diff location within the genome . These are of two types- 1. SINE ( short interspersed elements) 2. LINE( long interspersed elements)
1.SINE ( short interspersed elements)- These are about 300 bp long and may be present about 5 lakh times in human genome. Ex Alu sequence are the best characterized SINEs in human.
These
are termed as Alu elements because they
contain specific nucleotides sequence which are cleave by the
restriction enzyme named Alu1 .Alu elements contains direct terminal repeats
DTR of 7 to 20 bp length. This dtr help them in the insertion process during
transposition.
2.LINE -(long interspersed elements): They are about 6499 bp long and present about 1llakh time in the human genome . Most prominent ex. Is L1 sequence. This transposible elements are some of the most abundant & common families of moderately repeated sequences in human DNA.
SIGNIFICANT IF TRANSPOSABLE ELEMENTS:
1. Trans may changed the structural snd functional characteristics if genome by changing their position in the genome.
2. They may caused mutation. Insertion. Deletions etc.
3. Transposon a make positive contribution in the evolution as they have tremendous impacts in the alternation if
genetic organization if organism. 4. They are useful as cloning vectors in gene
cloning and may also be used as genetic markers during genome maping.