Science Buddies: "Ask an Expert"

Hello, I'm studying Bacterial Transposons and have come on to the topic TGE.

I'm confused, are Bacterial Transposons same as TGE?

The four types of TGEs i'm studying are IS (insertion sequence) elements, composite transposons Tn5, Non composite transposons Tn 3, and certain temperate bacteriophages eg. Mu.

Can you help me clarify my doubts?

IS element:

Direct repeat-----Indirect repeat------gene-----Indirect R---Direct repeat

the direct repeat is part of the host DNA

and Tn 5 consists of central region carrying gene/genes, and has IS elements at both ends. Which means:

IS ------------- gene -------------------- IS

do the both ends of IS (including the sides joined to the gene) have direct repeats (which are host DNA)?

Is there any good websites with relevant pictures?? I'm very confused now.

Hi Bobby,

Transposable elements can occur in other organisms so the term TGE is more broad than just bacterial transposons. There are some well known occurances of transposable elements in corn, that were discovered by Barbara McClintock and won her the Nobel prize. Bacterial transposons are one type of TGE.

I was unable to find any good pictures of bacterial transposons on the web but there are some textbooks that would have these if you can get to a college library. "Genes" by Lewin is an excellent moelcular biology book with good illustrations and should have something that covers your examples.
There is this example of a simple eukaryotic transposition that is similar to aa bacterial transposon
http://bssv01.lancs.ac.uk/ADS/BIOS336/336L4.html

good luck,
Caroline