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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.      

#SCPH06 I Botany
  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: 15652

#SCPH01 Biochemistry

You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. You have isolated a mutation that causes constitutive melibiase activity, which you designate MelA–. P1 phage mapping experiments using a Tn5 insertion linked to Mel1 show that MelA– is not linked to Mel1. Moreover you find that when an amber suppressor is introduced into a MelA– mutant, normal melibiase regulation is restored. Classify the MelA– mutation in terms of its basic genetic properties, 
TLS Online TPP Program

#Question id: 1597

#SCPH01 Biochemistry

Daudi tumor cells, caused due to mutation in?
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#Question id: 404

#SCPH28 | Zoology

When a mixture of 3-phosphoglycerate and 2-phosphoglycerate is incubated at 25 °C with phosphoglycerate mutase until equilibrium is reached, the final mixture contains six times as much 2-phosphoglycerate as 3-phosphoglycerate.  Which one of the following statements is most nearly correct, when applied to the reaction as written?  (R = 8.315 J/mol·K; T = 298 K)  3-Phosphoglycerate -> 2-phosphoglycerate
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#Question id: 13048

#SCPH28 | Zoology

In HAT selection surviving cells synthesise nucleotides by means of:
TLS Online TPP Program

#Question id: 5046

#SCPH06 I Botany

During early cleavage stages in drosophila, nuclei divide through 13 cycles in the absence of any cytoplasmic cleavage. This division creates an embryo of many nuclei contained within one shared cytoplasm surrounded by one common plasma membrane, this process is called as-