BIOL308 Lecture Notes - Lecture 20: Dna-Binding Domain, Operon, Repressor

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purplemosquito736

16 Jul 2014

School

University of Waterloo

Department

Biology

Course

BIOL308

Professor

Bruce Wolff

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Document Summary

Same regulatory protein acts as both activator and repressor = regulator two different conformations/corresponding binding sites. Autoregulaton of arac and cap regulation of the operon. Operator regions - more complicated then previously shown. If either o2 or o3 are missing; 500-fold. Repressor binds as a tetramer: could bind to all three of them. Dna looping; rnap prevented from binding to promoter. Also: presence of auxiliary operators (o2 and o3) near the functional operator (o1) increase the local concentration of the repressor, so that it can occupy the functional operator (o1) Monitors specific changes in the environment (level or nutrients, ph, solvent ceoncentration-osmolarity, etc. ) Either stimulates or represses regulation of specific genes. Changes in gene expression necessary for bacterium to adapt to environmental change. Sensor is an outer part which detects specific changes in environment transmitter is an inner part which usually acts as a kinase.

Related Questions

1. What is the term when the product of a biochemical pathway inhibits the activity of the first enzyme of a pathway?

		feedback inhibition.
		activator inhibition.
		diffusional regulation.
		enzyme activation.

2. Through control of gene expression, prokaryotes respond to changing __________ conditions.

		internal
		protein
		environmental
		genetic

3. A protein that negatively regulates transcription by binding to the operator is known as the

		operon
		repressor
		activator
		inducer

4. During attenutation, when tryptophan levels are high, the ________ stem-loop forms and transcription ________ the trpL gene.

		1-2, ends just past
		3-4, ends just past
		1-2, continues beyond
		3-4, continues beyond

5. The process of turning on the expression of a gene in response to a substance in the environment is called:

		constituation.
		repression.
		induction.
		catabolism.

6. What is a function of some specific transcription factors?

		to bind to the promoter region of the gene to facilitate the proper alignment of the RNA polymerase
		to bind to the centromere to induce meiosis
		to bind to enhancer regions to help regulate gene transcription
		to bind to the operator to recruit sigma factor

7. How does exposing an E.coli cell to glucose affect the regulation of the lac operon via CAP?

		cAMP binds to CAP and transcription is increased.
		cAMP binds to CAP and transcription is decreased.
		cAMP does not bind to CAP and transcription is increased.
		cAMP does not bind to CAP and transcription is decreased.

8. The lac repressor protein works when mutations in the repressor gene and structural genes are:

		in cis or in trans.
		in trans only.
		in cis only.
		in both prokaryotes and eukaryotes.

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BIOL308 Lecture Notes - Lecture 20: Dna-Binding Domain, Operon, Repressor

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