BIOL 102 Chapter Notes - Chapter 18: Lac Operon, Lac Repressor, Catabolite Activator Protein

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4 May 2016

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Natural selection favour bacteria that only express the genes who"s products are needed by the cell. Feedback inhibition: a product that is also an inhibitor when a lot is produced. Grouped genes of related function into one transcription unit for s single on-off switch makes the genes coordinately controlled. Operator: sequence of nucleotides at the start of an operon to which an active repressor can attach. Positioned within the promoter or between the promoter and enzyme-coding genes. Promoter: site where rna polymerase can bind to dna to start transcription. Ex. -trp operon is in bacteria and is repressible operon that controls the production of tryptophan and. By itself, it is turned on so tryptophan can be made, and is switched off my a repressor. Repressor: protein that binds to the operator and blocks the attachment of rna polymerase to the promoter.

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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BIOL 102 Chapter Notes - Chapter 18: Lac Operon, Lac Repressor, Catabolite Activator Protein

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