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TLS Online TPP Program

#Question id: 16127

You are studying regulation of the yeast enzyme glutamine synthetase (GS), which is encoded by the GLN1 gene. You have isolated two mutants, designated  gln2– and gln3–, that give decreased GS activity. Mating of either gln2– or gln3– haploids to wild type produces heterozygous diploids that show normal amounts of GS expression. When you cross either a gln2– or gln3– haploid to a gln1– strain the resulting diploids show normal expression of GS.
The GLN1 gene shows a rather complex regulation in response to different amino acids. When either glutamate (glu) or glutamine (gln) is added to the medium, the amount of GS expression diminished and when both glutamate and glutamine are added to the medium GS expression is shut off completely. The effects of different mutants on the response to glu and gln are shown below.
Which of the models from best fits these experimental results? Complete the model for the regulation of GLN1 that includes the effects of glu and gln.      

#Unit 13. Methods in Biology
  1. Parallel model best fits the experimental results, addition of glutamate (glu) and glutamine (gln) dependently regulate the GS activity
  2. Parallel model best fits the experimental results, addition of glutamate (glu) and glutamine (gln) independently regulate the GS activity
  3. linear model best fits the experimental results, addition of glutamate (glu) and glutamine (gln) dependently regulate the GS activity
  4. linear model best fits the experimental results, addition of glutamate (glu) and glutamine (gln) independently regulate the GS activity
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TLS Online TPP Program

#Question id: 12265

#Unit 10. Ecological Principles

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TLS Online TPP Program

#Question id: 11811

#Unit 6. System Physiology – Plant

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TLS Online TPP Program

#Question id: 31197

#Unit 4. Cell Communication and Cell Signaling

Notum inhibits Wnt signaling by: 
TLS Online TPP Program

#Question id: 5145

#Unit 5. Developmental Biology

Doris Taylor’s research group used detergents to remove all the cells from a cadaveric rat heart, which left behind the natural extracellular matrix. Proteins such as fibronectin, collagen, and laminin held together the rest of the extracellular matrix and maintained the intricate shape of the heart. The researchers then infused this extracellular matrix scaffold with cardiomyocyte progenitor cells. Surprisingly, these cells differentiated and organized into a functionally contracting “recellularized” heart. The behavior of extracellular matrix scaffold can promote the differentiation and rebuilding of a beating heart is analogous to which of the interactions?
TLS Online TPP Program

#Question id: 28839

#Unit 2. Cellular Organization

Which of the following nucleates assembly of a microtubule by forming a template corresponding to the (−) end?