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.