Operons

You want your bacterial culture to grow well so you made an enriched media with all forms of carbohydrates. Which of this carbohydrate should you restore first if you want the culture to keep growing at the same rate?

• Glucose

• Lactose

• Galactose

• Fructose

Which of these operons is anabolic?

• Lac

• Ara

• Trp

• Phe

Which of these systems give the best mode for turning trp operon off?

• Repressor

• Attenuator

• Repressor with a downstream poly A tail

• Repressor with an attenuator

A Lac repressor is a tetramer repressed when bound to the inducer. The trp repressor is a ____________________

• Dimer inactivated when bound to the inducer

• Dimer activated on inducer binding

• Tetramer inactivated on inducer binding

• Tetramer activated on inducer binding

When uncharged tRNA concentration is low what will you expect as the activity of tryptophan operon?

• Low

• Medium

• High

• Very high

We know that lactose has a positive impact on the activity of the lac operon. Tryptophan’s presence has a ________________

• Positive feedback

• Negative feedback

• No difference

• Highly positive impact

Which segments of the attenuator together form the repression loop?

• Segment 1-2

• Segment 2-3

• Segment 3-4

• Segment 1-4

Which of these properties do not agree with trp operon attenuator?

• It brings about repression of trp operon

• It consists of one stem loop system

• It has two codons for tryptophan in sequence

• Ribosome stalls at the attenuator

Which of the Ara operon regulation site is actually preventing RNA polymerase from binding and producing the Ara genes BAD?

• O1

• O2

• P

• Z

Which of these Ara genes is a mode of feedback autoregulation?

• Ara A

• Ara B

• Ara C

• Ara D