Mutant Analysis of Lac Operon The Operon and its Control Elements Given the lac
ID: 90782 • Letter: M
Question
Mutant Analysis of Lac Operon The Operon and its Control Elements Given the lac Operon (pictured above) and what you know about the regulation of gene expression in this out the last column in the table below. II. Gene Regulation Details How are most genes regulated (at the level of transcriptional, translational, or replication)? a. Why is this form of gene regulation advantageous? b. Are genes regulated at the level of DNA replication (i.e. some genes are replicated while not)? Why or why not?Explanation / Answer
I. LacZ+Lacl+Lac P+LacO- : As the Lac operator is absent, the repressor cannot bind, therefore beta galactosidase can be produced
LacZ+LacI-Lac P+ LacO+ : As LacI is absent, the repressor will not be produced, therefore beta galactosidase will be produced
II. Most genes are regulated at the transcriptonal level.
a. Regulation at transcriptional level is much easier than translational control as there will be no need to control the continous stream of various types of mRNAs for the different genes. In such a scenario, activation of a required mRNA from a stream of inactivated mRNAs will be even more difficult. Control of transcriptional factors and RNA polymerase is much easier for the cell.
b. No, genes are not regulated at the level of DNA replication, as the job of mitotic DNA replication is to produce exact copies of the DNA, and any sort of mutation is unintentional. DNA replication is not specific either, and cannot exclude parts of the DNA during replication.
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