Molecular iology Course-quiz 3 Chapter 16-18(90 min) December22,2006 Total 130 points Note: the answers should be concise and hit the points(答案要尽量简明和击中要 点) 1. What are the gene expression stages that can be regulated? (10 points) Regulated stages in gene expressio (1)transcription initiation(the most important stage): RNAP binding of the promoter, transition from the closed complex to the open complex; promoter (2)stages after initiation(elongation and termination ()RNA processing(alternative splicing)in eukaryotes 2 (4)translation 2. What is the recruitment regulation? Please describe an example of this kind of gene regulation in bacteria. 10 points Recruitment regulation: refers to the regulator protein bound to a dna egion can recruit the components in the transcription machinery or the nucleosome modifier, and thus exert an alteration of the transcription level. This class of regulator has a dNa binding domain and a protein interaction domain For example, in Lac operon of E. coli, the activator CAP binds to the CAP binding site and recruits the rna polymerase to bind its promoter efficiently for transcription initiation. (Other correct example will also do) 3. What is the allostery regulation? Please describe an example of this kind of gene regulation in bacteria. (10 points Allostery regulation: binding of the transcription activator induces a conformational change in the transcription complex (either polymerase or promoter DNA), which transforms the transcription complex from the inactive form to the active form, resulting in transcription activation. 5 Examples include activators NtrC and Merr, which work by induce onformational change in the polymerase and promoter dna respectively.(One example will suffice) 4. How the expression of a tryptophan operon is regulated? (15 points) The expression of tryptophan operon are controlled by two layers of regulation 1) At the transcription initiation stage: E. coli encodes a trp repressor, however the repressor alone cannot bind to the operator. Tryptophan acts as a corepressor of the trp operon. When the tryptophan level is high in bacteria, it binds to the trp repressor and the complex binds to the operator to repress the transcription initiation 2) Attenuation: a regulation by premature transcription termination within the leader rnaMolecular Biology Course- quiz 3 Chapter 16-18 (90 min) December 22, 2006 [Total 130 points] Note: the answers should be concise and hit the points (答案要尽量简明和击中要 点)。 1. What are the gene expression stages that can be regulated? (10 points) Regulated stages in gene expression: (1) transcription initiation (the most important stage): RNAP binding of the promoter, transition from the closed complex to the open complex; promoter escape 4’ (2) stages after initiation (elongation and termination) 2’ (3) RNA processing (alternative splicing) in eukaryotes 2’ (4) translation 2’ 2. What is the recruitment regulation? Please describe an example of this kind of gene regulation in bacteria. (10 points) Recruitment regulation: refers to the regulator protein bound to a DNA region can recruit the components in the transcription machinery or the nucleosome modifier, and thus exert an alteration of the transcription level. This class of regulator has a DNA binding domain and a protein interaction domain (region). 5’ For example, in Lac operon of E. coli, the activator CAP binds to the CAP binding site and recruits the RNA polymerase to bind its promoter efficiently for transcription initiation. (Other correct example will also do) 5’ 3. What is the allostery regulation? Please describe an example of this kind of gene regulation in bacteria. (10 points) Allostery regulation: binding of the transcription activator induces a conformational change in the transcription complex (either polymerase or promoter DNA), which transforms the transcription complex from the inactive form to the active form, resulting in transcription activation. 5’ Examples include activators NtrC and MerR, which work by induce conformational change in the polymerase and promoter DNA respectively. (One example will suffice) 5’ 4. How the expression of a tryptophan operon is regulated? (15 points) The expression of tryptophan operon are controlled by two layers of regulation: 1) At the transcription initiation stage: E. coli encodes a trp repressor, however the repressor alone cannot bind to the operator. Tryptophan acts as a corepressor of the trp operon. When the tryptophan level is high in bacteria, it binds to the trp repressor and the complex binds to the operator to repress the transcription initiation. 5’ 2) Attenuation: a regulation by premature transcription termination within the leader RNA. 2’