Mobile DNA: Transposons Flashcards
Who first identified transposons?
Barbara McClintock
How were transposons first identified?
In maize, transposons were found to be ‘controlling elements’ in the phenotypic expression of kernel color patterns
What are the three types of transposons?
- DNA only cut-and-paste element 2. LTR element 3. non-LTR element
What are the two functions of transposons?
Non-replicative, cut and paste transposition and replicative, nick and paste transposition
What is a retrotransposon?
A transposon which utilizes an RNA intermediate using reverse transcriptase
What is a non-LTR element?
True or false: transposons are found in all three domains of life.
True!
Where in the genome are transposons inserted?
Transposons can insert at random target sites in the genome
Can transposons move outside of the cell in which they are found?
No, most (but not all) transposons are confined to moving within the DNA of a single cell
What is a characteristic effect that transposition has on the DNA sequence it is inserted into?
Insertion results in a characteristic target site duplication
What is unique about autonomous transposons?
Autonomous transposons encode all the essential proteins required for their transposition
What is the co-dependent relationship between autonomous and non-autonomous transposons?
Non-autonomous transposons do not encode functional transposition proteins but instead rely on proteins encoded by other (autonomous) transposons
What are the metazoa?
The division of the animal kingdom that is multicellular animals with differentiated tissues
Transposable element-derived sequences are a
major component of…
metazoan genomes.
What is the genetic impact of transposon insertion?
Transposition disrupts gene function
How can transposons influence gene expression?
Some transposons carry promoters or other regulatory sequences which can influence nearby gene expression
What can recombination between transposons lead to?
deletion of essential chromosomal regions (host organism death)
Roughly how many human diseases are attributed to transposition?
More than 100 diseases.
Explain the series of steps between L1 insertion and haemophilia.
Craig et al. p671-673
What does LTR stand for?
Long terminal repeat
What is a long terminal repeat? (LTR)
What is the function of reverse transcriptase?
This enzyme synthesises DNA from an RNA template
What is the simplest bacterial transposon?
Insertion sequences (IS elements)
What is Tn10?
A compound transposon comprising two IS10 elements flanking a tetracycline-resistance gene
