University:
Tufts University
Course:
BIO 0041 | General Genetics
Academic year:

2020
Views:

348

Pages:

5
Author:

Haiden Dudley

PAL Problem Set Lecture 4 (Brooker Chapter 14) Transcriptional Regulation Section A. Regulation of gene expression What is gene expression? Can a single gene be transcribed multiple times within a cell? Can a single mRNA be translated multiple times within a cell? What are the different levels of gene (expression) regulation? Which is the most important? Why? List multiple reasons why gene regulation is important What is an operator? Where is the operator in relation to the promoter? What is an operon? Which organisms have operons? Section B. Regulation of the lac operon in E. coli What is the purpose of the genes encoded by the lac operon in E. coli? When are these gene products needed by E. coli? What would happen if E.coli lost its ability to regulate expression of the lac operon? What are the transcriptional regulatory proteins (activator and repressor) involved in lac regulation? What are the inducers for each regulatory protein? Be specific. What protein is encoded by the lacZ gene? What is the role of this protein in lactose metabolism? What protein is encoded by the lacY gene? What is the role of this protein in lactose metabolism? What protein in encoded by the lacI gene? What is the role of this protein in lactose metabolism? Is it a part of the lac operon? Explain. How does the presence of lactose in an E. coli cell lead to de-repression of the lac operon? What enzyme is involved? What is allolactose? What is cAMP? What are the cAMP levels inside the cell in relation to glucose? What is the CAP protein and where does it bind on DNA? If the lac operon is repressed in the absence of lactose, why do E. coli cells have small amounts of lactose permease and beta-galactosidase present at all times? What would happen to E. coli's ability to metabolize lactose if the LacI repressor protein was 100% efficient at blocking transcription of the operon? Would E. coli cells produce high or basal beta-galactosidase levels under each of the following growth conditions? For each condition, is CAP/cAMP bound to the CAP site? Is the LacI Repressor protein bound to the operator? minimum media + glucose: minimum media + lactose: minimum media + sucrose: minimum media + water: What are the lac operon expression levels in a lacI null mutant? If a second wild type or normal copy of the lacI gene (just lacI and not lacZ, lacY, or lacA) is introduced into the lacI mutant cell, what would be the lac operon expression levels in this partial diploid? What are the lac operon expression levels in an operator mutant, which prevents the binding of the LacI repressor? What are the lac operon expression levels in a CAP binding site mutant, which has a mutation in the CAP binding site of the lac operon?