Homework SourseBio cell and molecular Answer ALL 1 although all of the step
Bio: cell and molecular
Answer ALL
1 although all of the steps involved in expressing a gene can in principle be regulated, for most genes the initiation of __________ is the most important point of control.
2 the general transcription factors that assemble at a eukaryotic promoter are different, depending on the specific gene being transcribed by polymerase II.
True or False?
3 Which of the following describes the lac operon in E. coli when lactose, but not glucose, is present in the culture medium?
A) CAP, but not the lac repressor, is bound to the lac operon\'s regulatory DNA, and the lac operon is expressed.
B) CAP and the lac repressor are both bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
C) The lac repressor, but not CAP, is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
D) Neither CAP nor the lac repressor is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
Bio: cell and molecular
Answer ALL
1 although all of the steps involved in expressing a gene can in principle be regulated, for most genes the initiation of __________ is the most important point of control.
2 the general transcription factors that assemble at a eukaryotic promoter are different, depending on the specific gene being transcribed by polymerase II.
True or False?
3 Which of the following describes the lac operon in E. coli when lactose, but not glucose, is present in the culture medium?
A) CAP, but not the lac repressor, is bound to the lac operon\'s regulatory DNA, and the lac operon is expressed.
B) CAP and the lac repressor are both bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
C) The lac repressor, but not CAP, is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
D) Neither CAP nor the lac repressor is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
Answer ALL
1 although all of the steps involved in expressing a gene can in principle be regulated, for most genes the initiation of __________ is the most important point of control.
2 the general transcription factors that assemble at a eukaryotic promoter are different, depending on the specific gene being transcribed by polymerase II.
True or False?
3 Which of the following describes the lac operon in E. coli when lactose, but not glucose, is present in the culture medium?
A) CAP, but not the lac repressor, is bound to the lac operon\'s regulatory DNA, and the lac operon is expressed.
B) CAP and the lac repressor are both bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
C) The lac repressor, but not CAP, is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
D) Neither CAP nor the lac repressor is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
1 although all of the steps involved in expressing a gene can in principle be regulated, for most genes the initiation of __________ is the most important point of control.
2 the general transcription factors that assemble at a eukaryotic promoter are different, depending on the specific gene being transcribed by polymerase II.
True or False?
3 Which of the following describes the lac operon in E. coli when lactose, but not glucose, is present in the culture medium?
A) CAP, but not the lac repressor, is bound to the lac operon\'s regulatory DNA, and the lac operon is expressed.
B) CAP and the lac repressor are both bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
C) The lac repressor, but not CAP, is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
D) Neither CAP nor the lac repressor is bound to the lac operon\'s regulatory DNA, and the lac operon is not expressed.
Solution
All three of these systems work in concert to integrate signals from the cell and change the transcriptional program accordingly. Three distinct families of DNA sequence elements direct transcription by pol ll. Teh first family included the core, or basal, promoter elements found near the site where pol ll initiates transcription. Two classes of core element have been identified: the TATA element, located- 25-30 base pairs upstream of the transcription start site (consensus TATAa/tAa/t), and the lnitiator motif, a pyrimidine- rich sequence(consenus PyPyA+INT/APyPy) encompassing the transcription start site. The TATA and lnitaiator elements, which serve to nucleate the initiation complex, are recognized by components of the transcription machinery.
3. The lac repressor, but not CAP is bound to the lac operon\'s regulatory DNA and the lac operon is not expressed.
