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TLS Online TPP Program

#Question id: 2677

Why is the transcription of structural genes of the trp operon turned off in the presence of tryptophan?

#Unit 2. Cellular Organization

  1. Tryptophan is the repressor that binds to the operator, preventing transcription.

  2. The structural genes are used to make tryptophan, which would not be needed if tryptophan is available.

  3. Tryptophan has no effect on the transcription of the structural genes.

  4. Tryptophan RNA polymerase from finding the promoter of the trp operon, preventing structural gene transcription.

More Questions
TLS Online TPP Program

#Question id: 2499

#Unit 2. Cellular Organization

Capture of microtubule (+) ends by chromosomes occurs during:
TLS Online TPP Program

#Question id: 1005

#Unit 1. Molecules and their Interaction Relevant to Biology

The first step in the de novo biosynthesis of IMP is a reaction between glutamine and PRPP. Which statement is not true about this reaction?
TLS Online TPP Program

#Question id: 2925

#Unit 2. Cellular Organization

Mitotic cyclin levels in early Xenopus embryos are regulated by:
TLS Online TPP Program

#Question id: 31373

#Unit 2. Cellular Organization

Which of the following protease breaking the cohesin circles and allowing sister chromatids to be pulled apart by the spindle apparatus that is pulling them toward opposite spindle poles?
TLS Online TPP Program

#Question id: 14882

#Unit 4. Cell Communication and Cell Signaling

In bone marrow, stem cells are committed to different lineages. Factors that stimulate colonies of these different lineages are interleukin-3 (multi-CSF), IL-7,  granulocyte- macrophage colony stimulating factor (GM-CSF) and granulocyte or macrophage colony- stimulating factor (G-CSF or M-CSF). In a mouse deficient in IL-7 the number of which cells will not be altered