TLS Online TPP Program

#Question id: 7191


In tunicate embryo, Presumptive endoderm originates from the vegetal A4.1 and B4.1 blastomeres. The specification of these cells coincides with the localization of β-catenin. Which of the following statement is incorrect?

#Unit 5. Developmental Biology
  1. Inhibition of β-catenin results in the loss of endoderm and its replacement by ectoderm in the tunicate embryo.
  2. increasing β-catenin synthesis causes an increase in the endoderm at the expense of the ectoderm (just as in sea urchins).
  3. The β-catenin transcription factor appears to function by activating the synthesis of the homeobox transcription factor Lhx3. Inhibition of the lhx3 message prohibits differentiation of endoderm.
  4. During the differentiation of endoderm β-catenin inhibits the synthesis of Lhx3. Expression of Lhx3 message causes differentiation of ectoderm.
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TLS Online TPP Program

#Question id: 4461

#Unit 3. Fundamental Processes

According to some experiments, during initial transcription, the polymerase remains stationary on the promoter, unwinds downstream DNA, and pulls that DNA into itself, which model is this?

TLS Online TPP Program

#Question id: 4462

#Unit 3. Fundamental Processes

Promoter escape is associated with the breaking of all interactions (at the given promoter) between;

TLS Online TPP Program

#Question id: 4463

#Unit 3. Fundamental Processes

___?____ is a way to store and mobilize energy during transcription initiation, and its release upon escape is what enables polymerase to break free of the promoter and dislodge s factor from the core.

TLS Online TPP Program

#Question id: 4464

#Unit 3. Fundamental Processes

Role of Gre factor;

TLS Online TPP Program

#Question id: 4465

#Unit 3. Fundamental Processes

Main function of Nus proteins in transcription,

TLS Online TPP Program

#Question id: 4466

#Unit 3. Fundamental Processes

As well as synthesizing the transcript, RNA polymerase performs two proofreading functions on that growing transcript;

i. Pyrophosphorolytic editing

ii. Hydrolytic editing

Choose correct processes accordingly,

A. The polymerase backtracks by one or more nucleotides and cleaves the RNA product, removing the error-containing sequence.

B. In this, the enzyme uses its active site, in a simple back-reaction,

C. Catalyze the removal of an incorrectly inserted ribonucleotide, by reincorporation of PPi

D. The enzyme can then incorporate another ribonucleotide in its place in the growing RNA chain.