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: 904

#Unit 1. Molecules and their Interaction Relevant to Biology

In addition to self assembly, some proteins fold with the help of

TLS Online TPP Program

#Question id: 905

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is correct about chaperones

A) renature and denatured proteins.

B) help cells repair damage due to heat shock.

C) assist protein self assembly.

D) donot use ATP to fold proteins.

TLS Online TPP Program

#Question id: 906

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is least likely to result in protein denaturation?

TLS Online TPP Program

#Question id: 907

#Unit 1. Molecules and their Interaction Relevant to Biology

Thermodynamics of protein folding is depicted as a free energy vs folding process:

Choose the correct match for regions mentioned in the figure

A.

1. Molten globule

B.

2. Unfolded

C.

3. Transition state

D.

4. Folded

TLS Online TPP Program

#Question id: 908

#Unit 1. Molecules and their Interaction Relevant to Biology

Molecular chaperones are a class of proteins that play a role

TLS Online TPP Program

#Question id: 909

#Unit 1. Molecules and their Interaction Relevant to Biology

Most proteins denature at both high and low pH. At high pH, the ionization of internal tyrosines is thought to be the main destabilizing influence, whereas at low pH, the protonation of buried histidines. A titration curve for the unfolding of the enzyme ribonuclease is shown in Figure. Given the relation between the titration curves for protein unfolding and histidine protonation, which of the following conclusion can be drawn correctly?

A. The sharp transition in graph indicates a highly cooperative process; when the protein starts to unfold, it completes the process rapidly

B. The sharp transition in graph indicates a highly noncooperative process

C. Several buried histidines can ionize when the chain starts to unfold, so that when one goes, they all go together due to cooperative behaviour of protein folding

D. Buried histidine (pK of 4 in this example) becomes accessible to solvent, its pK will shift toward its normal value of 6, significantly steepening its titration curve.