BSC 2010 Lecture Notes - Lecture 11: Lac Operon, Central Dogma Of Molecular Biology, Operon

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golddonkey719

25 Mar 2015

School

University of Florida

Department

Biology - Biological Sciences

Course

BSC 2010

Professor

Fatma Kaplan

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Document Summary

Gene expression: final production of a functional gene product. Genomic totipotency: all somatic cells share the same dna. Constitutive expression: refers to genes that are always on. Luxury genes: needed only by specific genes (liver and cancer cells) Control mrna stability, translational control of protein synthesis, post translational control of protein activity (total of 5 controls) during central dogma. Prokaryote gene regulation: few regulatory controls for multiple structural genes. Eukaryotes gene regulation: multiple regulatory controls for single genes. Negative control: inhibition of transcription on the dna. Positive control: enhancement of transcription on the dna. Lac operon( positive controls) (we know what z and y does but not areferring to figure in lecture) When lactose is absent, operon is turned off (to conserve cell responses) When lactose is present, now need these three enzymes and operon turned on to synthesize enzymes to metabolize the available lactose. Promoters are always a short distance, upstream (5"), of their gene.

Related Questions

1.) What type of control best describes the lac operon when it is regulated by allolactose? Explain the features of this type of regulation using the lac operon as an example.

2.) What is positive gene regulation?

a) when an activator protein binds to the operator of a gene to turn expression off

b) when a repressor protein binds to the operator of a gene to turn expression off

c) when an activator protein binds to the operator of a gene to turn expression on

d) when a repressor protein binds to the operator of a gene to turn expression on

e) when a protein binds to DNA to change gene expression

3.) In the lactose operon of E. coli, what is the function of each of the following genes or sites: a) regulator, b) operator, c) promoter, d) structural gene Z and e) structural gene Y?

a) regulator gene

b) operator

c) promoter

d) structural gene Z

e) structural gene Y

4.) In a negative, repressible regulatory mechanism, transcription of the structural gene(s) occurs in

a) the presence of the co-repressor, but not in its absence.

b) the absence of the co-repressor, but not in its presence.

c) the presence of the inducer, but not in its absence.

d) the absence of the inducer but not in its presence.

e) the absence or presence of the co-repressor.

What are answers and can you explain them to me?

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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BSC 2010 Lecture Notes - Lecture 11: Lac Operon, Central Dogma Of Molecular Biology, Operon

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