MCB 150 Lecture 33 Flashcards

Flashcards for reviewing bacterial and eukaryotic gene regulation from MCB 150 Lecture 33.

What can be adjusted once transcription has occurred in bacteria?

Levels of β-gal, permease, and transacetylase can be adjusted after transcription.

What is the approximate half-life of bacterial mRNAs?

Bacterial mRNAs have a rapid turnover rate of ~2 minutes.

From which end is lac mRNA degraded?

lac mRNA is degraded from the 3' end.

What affects how much protein is made from a gene at the level of translation initiation?

The 'strength' or closeness to consensus of the Shine-Dalgarno sequence.

What is the order of protein production quantity, from highest to lowest, in the lac operon?

β-gal > permease > transacetylase.

Besides strength, what else affects translation initiation?

Availability of the Shine-Dalgarno sequence.

What is an inducible operon?

An operon that can be turned on when needed.

Which operon is on by default?

The tryptophan (trp) operon.

What is a repressible operon?

An operon that can be turned off when its product is abundant.

Which level of regulation saves the most energy?

Transcriptional level.

Which level of regulation takes effect fastest?

Post-translational level.

What is another example of regulation of overall protein activity, like regulation of PFK in glycolysis?

Allosteric regulation or feedback inhibition of proteins.

Why are different levels of regulation balanced?

To make precisely the correct amount of functional protein under the given conditions.

Name two ways the levels of β-gal, permease, and transacetylase can be adjusted once transcription has occurred?

mRNA stability and translation initiation.

What is the difference between the lac and trp operons in terms of their default state and regulation?

The lac operon is inducible, while the trp operon is repressible.