WONDER WHY OPERONS?
by Arthur W. Siebens, Ph.D., Copyright 1999
(to the tunes of "Who Wrote the Book of Love," by Warren Davis, George Malone
and Charles Patrick and "Runaway," by Del Shannon)

(to the tune of "Who Wrote the Book of Love")
There's a hundred thousand genes, you know, in each human cell
The right genes on, the wrong genes off-that's why your nose can smell
Some genes are induced-others are repressed
Got to under, under, under-stand how [HOW!] How genes become expressed
We'll focus on bacteria-we understand them well
You solve human gene expression-you'll get nice prize from Nobel!

You've got this thing called the Lac operon-regulates a group of genes
That control lactose metabolism-the most important is lacZ
It codes for B-galactosidase-it breaks down lactose, yes
So let's under, under, under-stand when [WHEN!] When lacZ's expressed.
You've got an active repressor from the regulatory gene
It binds to the operator-just like a lock and key.

Now if it's bound, RNA polymerase is stuck right in its tracks
Bound to the promoter, the repressor won't let it pass
But in the presence of an inducer (allolactase), the repressor is released
And it's no wonder, wonder, wonder, wonder why [WHY!] (RNA) Polymerase reads lacZ.

(to the tune of "Runaway")
Induction's how lacZ's expressed, other genes are "on" unless repressed
The Trp operon's the classic case
It controls the tryptophan that's made-if you feed cells tryptophan there's blockade
The cell synthesizes just a trace.

Tryptophan's a corepressor-activates the inactive repressor
Now the active repressor binds (to the operator)-(RNA) polymerase can't read its lines (5 genes)
It's no wonder-why, why, why, why, why-tryptophan's not made
The repressor activates-and stops (RNA) polymerase
It stop, stop, stops polymerase
So by transcribing at the right pace
Operons control what's made
Yes, by transcribing at the right pace
Operons control what's made.