BIOL 2112 Chapter Notes - Chapter 24: Messenger Rna, Lac Repressor, Catabolite Activator Protein
19 Nov 2018
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Lecture 24 - Bacterial Gene Regulation
1)Bacteria respond to changes in their environments, such as nutrient availability, by
regulating their metabolic pathways. Describe two mechanisms that bacteria use in order
to adapt to environmental changes. Include in your answer which mechanism is a short-
term or long-term adaptation. (Pg. 364, paragraph 3, sentence 2; paragraph 4, sentence 1)
short term- The activity of the first enzyme in the pathway is inhibited by the pathway’s
end product— tryptophan, in this case. Thus, if tryptophan accumulates in a cell, it shuts
down the synthesis of more tryptophan by inhibiting enzyme activity. Such feedback
inhibition, typical of anabolic (biosynthetic) pathways, allows a cell to adapt to short-
term fluctuations in the supply of a substance it needs
long term- cells can adjust the production level of certain enzymes; that is, they can
regulate the expression of the genes encoding the enzymes. If, in our example, the
environment provides all the tryptophan the cell needs, the cell stops making the enzymes
that catalyze the synthesis of tryptophan. In this case, the control of enzyme production
occurs at the level of transcription, the synthesis of messenger RNA from the genes that
code for these enzymes.
TRP
LAC
Document Summary
1)bacteria respond to changes in their environments, such as nutrient availability, by regulating their metabolic pathways. Describe two mechanisms that bacteria use in order to adapt to environmental changes. Include in your answer which mechanism is a short- term or long-term adaptation. (pg. 364, paragraph 3, sentence 2; paragraph 4, sentence 1) short term- the activity of the first enzyme in the pathway is inhibited by the pathway"s end product tryptophan, in this case. Thus, if tryptophan accumulates in a cell, it shuts down the synthesis of more tryptophan by inhibiting enzyme activity. If, in our example, the environment provides all the tryptophan the cell needs, the cell stops making the enzymes that catalyze the synthesis of tryptophan. In this case, the control of enzyme production occurs at the level of transcription, the synthesis of messenger rna from the genes that code for these enzymes. What is an operon and what is the advantage to this gene structure? (pg.
