Transposons

Complete Presentation on Transposons. Its acts as mobile genetic elements..Non replicative transposons , Replicative transposons

1. Transposons For any query or suggestion please mail at:- [email protected]

2. Mobile genetic elements or transposons… Transposons are DNA sequence which can change position anywhere in the genome either in same chromosome or in different chromosome .. By Barbara McClintock ----  Maize endosperm… DNA Transposons are always DNA They are also known as transposable elements , mobile DNA sequence , Jumping DNA , Selfish DNA .. Types DNA Based transposons RNA Based Transposons ( reterotransposons ) Reteroposons

3. DNA Based transposons Non replicative transposons ( Cut –Paste Transposons). Cut DNA sequence from location and paste same DNA sequence to another Location. Number of DNA Sequence Same .. amount not increase.. example- IS elements(Insertional elements)  Bacteria. composite transposons  Bacteria AC/DS sequence  Maize P-Elements  Drosophila Hobo Elements  Drosophila Sleeping beauty  salmon

4. Replicative transposons – Copy paste transposons ( Replication ) Example- T3 elements in Bacteria .  transposible elements..

5. RNA Based Transposons ( R eterotransposons ) mRNA- --- RT  DS DNA -- Integrated in target site . Eg - Reterovirus --- HIV Reterovirus Like elements (RLE) Example Ty-1= yeast Copia = drosophila Gypsy = drosophila

6. R eteroposons Are replicative DNA Fragments which are inserted into chromosomes after they had been reverse transcribed from any RNA molecules .. Eg - F,G,L Elements = Drosophila Telomeric reteroposons = Drosophila LINES,SINES = Human LINES,SINES - short and long interspersed retrotransposable elements,

7. General characters of transposons All the transpose have at list one gene transposase gene and inverted terminal repeats (ITR). This ITR are specific for transposons . Transposase enzyme recognized the self DNA and cut it and also recognized the target site. Target site is not specific . They can carry out site specific recombination is illegitimate..

8. Cut –Paste transposons IS elements (Insertional elements)  Bacteria. simplest type of transposons IS -1,2,3,50..etc.. Discovered by – Jacob and monad = LacZ— Mutant.. They are very small – inverted terminal repeats (ITR) and transposase are present. They can carry out illegitimate Recombination

9. Composite transposons  Bacteria When two I.S( insertion sequences) element are present very close to each other they can move together and then carry other gene . Usually antibiotic resistance gene is present between two I.S element. eg - * Tn-5 Kanamycin R Gene Bleomycin R Gene Streptomycin R Gene Tn-9 = Chloramphenicol R Gene Tn 10 = Tetracyclin R Gene IS Gene IS

10. AC / DS Sequence Maize endosperm They discovered by Barbara Mc- Clintock white studying the the colour of endosperm .. AC DS Cis Acting Trans Acting AC= Activator = Trans / Cis Acting  Move independently DS = Dissociator  it does not has Transposase gene . it movement depend upon AC.

11. P- element Drosophila Present P-Cytotype Drosophila Absent M-Cytotype Drosophila mRNA Of Transposase Antisense RNA Repressor RNA

12. Replicative transposons ( Copy-paste Transposon) Eg - Tn-3 in bacteria Structure resembled with composite transposons Do not have I.S Elements Present inverted terminal repeats (ITR) sequences. Transposase Resolvase Target gene--> Beta Lactamase Resolvase

13. Reterotransposons Use RT-enzyme (Reverse Transcriptase) copy and paste mechanism -  Insert into target genome 42 % human genome made up on reterotransposons 2-3% other transposons . Eg - Reterovirus