TLS Online TPP Program

#Question id: 5670


Embryonic stem cells can be induced in the laboratory to differentiate into muscle, nerve, pancreatic, and other specialized cell types. It has recently become possible to trigger the dedifferentiation of somatic cells back into pluripotent cells (so-called induced pluripotent stem cells or iPS cells) by artificially enhancing the production of a relatively small number of key transcriptional factors known to be required for maintenance of pluripotency. Examples of such transcription factors are OCT4 and NANOG. The production of OCT4 and NANOG (and other key regulatory proteins) is stimulated by a transcription factor known as FOXP1, a member of the Forkhead family of DNA-binding proteins. There are two isoforms of FOXP1.

Which of the following statement regarding to FOXP1 is incorrect?

#Unit 5. Developmental Biology
  1. The protein encoded by the exon 18b–carrying mRNA is called FOXP1-ES: this activates genes (OCT4, NANOG, etc.) that promote dedifferentiation, and thus stimulates iPS cell formation.

  2. In the exon 18a–containing form encodes FOXP1 itself, and this has the opposite effect: it fails to stimulate expression of OCT4 and NANOG and instead actives genes that promote differentiation.

  3. FOXP1 binds to DNA via a domain known as a Winged helix, which recognizes a particular DNA sequence.

  4. The switch from exon 18a to exon 18b substitutes 3 residues in the Winged helix region of the protein including six amino acids that are known to contact DNA.

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TLS Online TPP Program

#Question id: 13050

#Unit 13. Methods in Biology

Which of the following expressions can be used in insects?

TLS Online TPP Program

#Question id: 13051

#Unit 13. Methods in Biology

Initiation of translation in higher eukaryotic organisms depends on a specific sequence of nucleotides surrounding the start (AUG) codon in the mRNA called……..

TLS Online TPP Program

#Question id: 13052

#Unit 13. Methods in Biology

What would be the effect on the PCR reaction if any of the following circumstances arose: 1) there are no primers in the reaction, 2) there are no dNTPs in the reaction, 3) there is no Taq polymerase in the reaction?

TLS Online TPP Program

#Question id: 13053

#Unit 13. Methods in Biology

What would the generally expected effect on the PCR reaction be of adjustments that increase the temperature of the annealing phase and the length of the elongation phase?

TLS Online TPP Program

#Question id: 13054

#Unit 13. Methods in Biology

Precision will be reduced, but yield will be increased
Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.
What would the expected effect be on a PCR reaction if the primers used were slightly shorter and more variable than the intended oligonucleotide sequences?

TLS Online TPP Program

#Question id: 13055

#Unit 13. Methods in Biology

Precision will be reduced, but yield will be increased
Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.
Which of the following will provide least specific amplification in qPCR?