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:- pradeep.devkate@gmail.com

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
1. DNA Based transposons
2. RNA Based Transposons (reterotransposons)
3. 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-
a. IS elements(Insertional elements)  Bacteria.
b. composite transposons Bacteria
c. AC/DS sequence  Maize
d. P-Elements  Drosophila
e. Hobo Elements  Drosophila
f. Sleeping beauty  salmon

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

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

6. Reteroposons
• 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