The previous question is this one : 6. The same E coli that you are studying in

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The previous question is this one :
6. The same E coli that you are studying in the research lab also encode the trp operon. You have isolated mutant E coli strains that do not regulate the trp genes normally. Below is the data you have collected comparing the mutant strains to normal (wildtype) Media without Trp a with T E. coli Strain Wild type Trp genes expressed Trp enes silenced Trp genes expressed Mutant Strain A Trp genes expressed Mutant strain B Trp genes silenced Trp genes silenced a. Which part of the trp operon and/or its regulatory genes is likely mutated to explain the growth results of Mutant Strain A? You may use a picture if you wish to help you explain. b. Which part of the trp operon and/or its regulatory genes is likely mutated to explain the growth results of Mutant Strain B? You may use a picture if you wish to help you explain. 7. Tumor suppressor genes are a family of genes that prevent tumors from forming in the body. Cancer cells often misngulate the expression of tumor suppressor genes. Which of the following changes would you expect to observe in a cancer cell? a. A high concentration of transcription factor activators of tumor suppressor b. Methylation at promoters of tumor suppressor genes Open chromatin around tumor suppressor genes d. Acetylated histones near tumor suppressor genes Explain your answer here:

Explanation / Answer

Answer:

6. a. The mutation may have occurred in the operator which makes it a Constitutive operator such that it is active all the time and does not sense the repressor. OR

Mutation may have occurred in the repressor such that it cannot bind to trp or to the operator. Thus the trp genes are expressed all the time.

b. Mutation may have occurred in the repressor such that it adopts an active conformation all the time and binds to the operator. This results in the trp gene expression to be repressed.

7. (b) Methylation at promoters of tumor suppressor genes.

Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription. Aberrant methylation of gene promoter regions is one of the mechanisms for inactivation of tumor suppressor genes in human malignancies.

Hypermethylation has been found to be associated with the inactivation of virtually all pathways involved in cancer development, including DNA repair, cell cycle regulation, apoptosis, cell adherence and detoxification pathways.

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