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TLS Online TPP Program

#Question id: 720

How would a homopolymer of alanine be more likely to form an alpha helix in water or in a hydrophobic medium?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. In an aqueous environment, the formation of intrachain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms. In an hydrophobic environment, these groups are stabilized by interaction with water, and so there is no energetic reason to form an a helix. Thus, the alpha helix would be more likely to form in a aqueous environment.

  2. In a hydrophobic environment, the formation of intrachain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms. In an aqueous environment, these groups are stabilized by interaction with water, and so there is no energetic reason to form an alpha helix. Thus, the alpha helix would be more likely to form in a hydrophobic environment.

  3. In both hydrophobic environment as well as aqueous environment, the formation of intrachain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms.

  4. In a aqueous environment, the formation of interchain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms. In an hydrophobic environment, these groups are stabilized by interaction with water, and so there is no energetic reason to form an alpha helix. Thus, the alpha helix would be more likely to form in a aqueous environment.

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TLS Online TPP Program

#Question id: 7195

#Unit 5. Developmental Biology

Given below are some of the statements regarding toll signalling pathway in drosophila.

A. Dorsal protein is a transcription factor with homology to the Rel/nuclear factor kappa B (NFκB) family of vertebrate transcription factors, which are involved in regulation of gene expression in vertebrate immune responses.

B. Toll signalling pathway is also used in the adult fly in defense against infection.

C. In the Drosophila embryonic Toll pathway Dorsal is held inactive in the nucleus by the protein Cactus.

D. The ligand for Toll is a fragment of the protein Easter, which is generated in the ventral vitelline space by the protease Spatzle.

E. When Toll is activated by binding the Spätzle fragment, its cytoplasmic domain binds a complex of the adaptor proteins dMyD88 and Tube. Tube interacts with, and activates, the protein kinase Pelle.

F. Activation of Pelle leads to the dephosphorylation of Cactus. This releases Dorsal, which is then free to enter a nucleus.

Choose the most appropriate combination of correct statements:
TLS Online TPP Program

#Question id: 10589

#Unit 10. Ecological Principles

We have seasonal breeding population of 1,000 organisms increasing at a finite rate of 15% per year. The population size will be after 4 year?
TLS Online TPP Program

#Question id: 24329

#Unit 4. Cell Communication and Cell Signaling

_______permit the passage of molecules as large as 1.2 nm in diameter (molecules smaller than 1200 Da).
TLS Online TPP Program

#Question id: 11261

#Unit 10. Ecological Principles

Which of the following kinds of social interactions cannot be favoured by natural selection under any circumstance?
TLS Online TPP Program

#Question id: 23253

#Unit 13. Methods in Biology

FISH is an in vitro assay that uses fluorescent reporter attached to a _______ that hybridizes to chromosomes.