Micro exam 2 practice "regulation" – Flashcards

Which of the following genetic elements is transcribed into a single mRNA?

Which operons are always transcribed unless deactivated

Which operons are never transcribed unless activated?

According to the animation, where on the DNA strand does a repressor bind?

When the cell is NOT in the presence of tryptophan,

When is the repressor protein transcribed?

Why is the tryptophan operon turned off in the presence of tryptophan?

What is the overall function of the trp operon?

how do the repressor proteins block the transcription of the structural genes?

What is the inducer molecule in the lac operon?

With which genetic region does the repressor protein interact?

When the cell is not in the presence of lactose,

What is the basic function of the lac operon?

to what genetic element does the RNA polymerase bind?

Define what an effector is in genetic regulation.

In certain circumstances, a single regulatory protein controls multiple operons. This situation would be called a(n) __________.

Regulation of an enzyme's activity occurs

In negative control of transcription, how does the presence of an inducer affect transcription?

Bacteria can regulate gene expression due to changes in the environment. How are these changes communicated to the cell?

The most frequent way in which regulatory RNA molecules exert their effects is by

Cyclic AMP is synthesized from ATP by an enzyme called ________ which is involved in ________.

How is the activity of a riboswitch controlled?

The major site of protein binding in DNA is the major groove. Why is this a good site for binding?

Which type of regulator(s) specifically bind to operator regions of DNA?

Which of the following examples describes a type of catabolite repression? The presence of abundant tryptophan inhibits the Trp operon. When glucose is present, the lac operon is inhibited. A mutation in the operator of the lac operon prevents the expression of the genes needed for the bacterium to utilize lactose. Allolactose binds to a repressor, preventing it from binding to the operator of the lac operon.

The promoters of positively controlled operons require activator proteins, because

Cells can regulate their metabolism by regulating enzyme activity or by regulating synthesis (i.e., by regulating whether they produce the enzyme for the reaction). Which of the following examples would be best when an enzyme needs to be available very rapidly?

Which of the following is an example of negative control with an inducible system? The Trp operon in E. coli is turned on by default. When there are sufficient amounts of tryptophan, a repressor can bind to the operator to turn off the operon. Additionally, when there are sufficient amounts of tryptophan, attenuation occurs and the operon is turned off. The lac operon in E. coli is turned off when lactose is not present. A repressor binds to the operator and prevents RNA polymerase from binding to the promoter. When allolactose (closely related to lactose) is present, it binds to the repressor and prevents the repressor from binding. In this way, the presence of lactose allows the operon to be turned on to express the genes need to use lactose. In the presence of oxygen, NifL represses the synthesis of nitrogenase. The maltose operons in E. coli are turned off by default. When maltose is present, it binds to the maltose activator protein. The maltose activator protein can then bind to the activator binding site to allow the genes of the operons to be expressed. (There are multiple operons all affected by the maltose activator protein).