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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: 5732

#Unit 8. Inheritance Biology

Consider a plant, such as maize, heterozygous for a paracentric inversion. The inversion is very small and a synapsed inversion loop does not occur in any of the cells. Which of the following statement is correct?
TLS Online TPP Program

#Question id: 8960

#Unit 9. Diversity of Life Forms

With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive.
1. ecdysozoan
2. protostome
3. eumetazoan
4. triploblastic
TLS Online TPP Program

#Question id: 11027

#Unit 7. System Physiology – Animal

Which of the following is the correct sequence of blood flow in birds and mammals?
TLS Online TPP Program

#Question id: 3436

#Unit 11. Evolution and Behavior

Loss of responsiveness to stimuli that convey little or no new information is called
TLS Online TPP Program

#Question id: 11091

#Unit 7. System Physiology – Animal

A diver is breathing 10% O2 at a pressure of 2000 mm Hg. The diver’s body temperature is 37°C, and PCO2 = 32 mm Hg. What is the alveolar PO2?