transposable genetic and plasmid

What are transposable genetic elements?

Segments of DNA that are able to move from one location to another.

Random movement. 

not capable of self replication 

What mediates the movement (transposition) of transposable elements?

Site-specific recombination, performed by the enzyme transposase.

What may accompany a transposition event?

A duplication may accompany the insertion.

What genes do insertion sequences (IS) carry?

Only the genes required for transposition.

No additional genes.

What is the nomenclature for insertion sequences?

Named as IS1, IS2,

What structural feature is found at both ends of an IS element?

Flanking inverted repeats.

What is the significance of IS element insertion?

• Causes insertional mutation

• Causes plasmid insertion

• Causes phase variation

What is the defining feature of a transposon?

It carries additional genes besides those needed for transposition.

What is the clinical importance of transposons ?

They contribute to antibiotic resistance.

Which enzyme is common to both IS elements and transposons?

Transposase.

Plasmid

Extrachromosomal genetic elements that are capable of autonomous replication 

Episome - a plasmid that can integrate into the host genome.

classification of plasmids

Transfer properties : conjugative and non-conjugative

Phenotypic effects : fertility, Bacteriocinogenic plasmid and Resistance plasmid ( R factor )