trp operons

Here is an excellent animation on the trp operon.

http://bcs.whfreeman.com/thelifewire/content/chp13/1302002.html

Everything will make sense after you go through the animation.

Next, here is an animation on the lac operon.



http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120080/bio27.swf::Combination%20of%20Switches%20-%20the%20Lac%20Operon

Differences:

Tryptophan acts directly in the repression system rather than as an inducer. This is a key difference between anabolic (biosynthesis) and catabolic (degradative) operons.

A simple on-off system for regulation of biosynthesis is not adequate to give fine control for biosynthesis.

Lac operon:

- encodes catabolic enzymes
- lactose (allolactose) is an inducer
- CAP regulation is involved
- lacl gene sitated just upstream of laczya gene cluster
- no transcriptional termination

Trp operon

-encodes anabolic enzymes
-tryptophan is a corepressor
-no cap involvment
-trpR gene situated a long way from trp gene cluster
- transcriptional termination as a fine control.

Bio_man 8)

Thanks so much that was a HUGE HELP!!!