BIOL 1123 Lecture Notes - Lecture 27: Conformational Change, Critical Role, Tata Box

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cyanreindeer497

13 Apr 2018

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Regulatory transcription factors: proteins that bind to dna near a promoter and affect the rate of transcription of one or more nearby genes. Repressors: transcription factors that bind to dna and inhibit transcription. Regulation by these proteins is called negative control. Activators: transcription factors that bind to dna and increase the rate of transcription. Regulation by these proteins is called positive control. Small effector molecules: critical role by binding to regulatory transcription factor and causing a conformational change in the protein. It decides whether or not the protein can bind to the dna. When a small effector molecule is synthesized it becomes available, it will bind to a depressor and cause a conformational change that inhibits the ability of the protein to bind the dna. One where the protein binds to the dna, and the other is the binding site for the small effector molecule. Induction: when transcription has been turned on by the presence of a small effector molecule.

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.

scarletwombat949

A transcription factor G can act as either a repressor or an activator of operon M, depending on its conformational state.

In one conformational state, transcription factor G binds site 1 in the promoter of operon M. When bound to site 1, it is an activator of operon M transcription. Factor G cannot bind to site 1 if ligand X is bound to it.

When factor G binds to ligand X, factor G undergoes a conformational change such that it now binds site 2 in the promoter and represses operon M. Because of the way in which it acts, ligand X would be called a(n) ____.

Imagine that there is a mutation in the gene that encodes transcription factor G such that operon M is always transcribed.

Which of these mutations in the gene that encodes transcription factor G is consistent with that outcome?

BIOL 1123 Lecture Notes - Lecture 27: Conformational Change, Critical Role, Tata Box

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