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ALI RAZA
BS ZOLOGY 5th SEMESTER
ROLL #4029
Presented To
• Mr. Danish Riaz
• Lecturer of Zoology
• Govt. Postgraduate
College ,
Samanabad
Faisalabad
INTRODUCTION
• transposon, A sequence of DNA that “jump” to different locations within a genome. Although these elements are frequently called “jumping genes,” they are always maintained in an integrated site in the genome. In addition, most transposons eventually become inactive and no longer move.
Contents
Introduction
Discovery of Transposons
Characteristics of Transposons
Types of Transposons
Mechanism of transposition
Transposons and disease
DiscoveryBarbara McClintock discovered the first TEs in
maize, Zea mays in 1948.
She was awarded a Nobel Prize in Medicine or Physiology in 1983 for her discovery of TE.
She noticed insertions, deletions, and translocations, caused by these elements. These changes in the genome could, for example, lead to a change in the colour of corn kernels. About 85% of the genome of maize consists in Tes.
1. Nbarobelprize.org
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(1983 Nobel Prize in Physiology and
Medicine)
2. profiles.nlm.nih.gov/LL/
Barbara McClintock 1902-1992Corn (maize) varieties
CLASS 2 ( Sim ple TN)
THESE CONSIST OF
THAT MOVES DIRECTLY FROM ONE PLACE ANOTHER.
CLASS 1 ( Retrotran sposon TN
These are retrotransposons that first the DNA Into RNA and then
Use reverse transcriptase to make a DNA copy of the RNA to insert in a new location
Transposition Pathways
Simple & Replicative Transposons
Known as Insertion Sequences - IS
bacterial
Tn10
eukaryotic
Ac/Ds
Simple Transposition
Direct repeats – DNA sequences that are identical and
run in the same direction (5’3’)
Inverted repeats - DNA sequences that are identical (or very
similar) but run in opposite directions
5’ CTGACTCTT 3’3’ GACTGAGAA 5’
5’ AAGAGTCAG 3’3’ TTCTCAGTC 5’and
Regulatory Sequences of Transposable Elements
5’ ATGACTGAC 3’3’ TACTGACTG 5’
5’ ATGACTGAC 3’3’ TACTGACTG 5’
and
transposon
1) Involves replication of the TE and insertion of the copy
into another chromosomal location
2) Only found in bacteria
Replicative Transposition
1) Very common but only occurs in eukaryotes
2) These types of elements are termed
retroelements or retrotransposons
3) Similar organization to retroviruses
Retrotranposons & Retrotransposition
Transposase Catalyzes Excision & Insertion
17-67
They are in the same
direction and are repeated
at both ends of the
element
TRANSPOSON and disease
1) They cause resistance against antibiotic.
2) They referred as ‘‘Selfish DNA’’.
3) They cause mutation.
4) Give rise to cancer.
5) A gap are formed in the gene after DNA
6) transposon.