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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: 21969

#Unit 2. Cellular Organization

Choose the correct statement 
a. Interphase chromosomes occupy chromosome territories in the nucleus and are not entangled with each other
b. Heterochromatic regions, silenced genes, and gene-sparse regions of chromosomes are typically localized to the nuclear periphery
c. Interphase chromosomes occupy chromosome territories in the nucleus and are entangled with each other
d. Heterochromatic regions, silenced genes, and gene-sparse regions of chromosomes are typically localized to the nuclear centre
TLS Online TPP Program

#Question id: 32518

#Unit 1. Molecules and their Interaction Relevant to Biology

When the antibiotic valinomycin is added to actively respiring mitochondria
TLS Online TPP Program

#Question id: 20283

#Unit 7. System Physiology – Animal

The following statements regarding to the pancreas and its function.
a. The pancreas is composed of two major types of tissues, (1) the acini, which secrete digestive juices into the duodenum, and (2) the islets of Langerhans, which secrete insulin and glucagon directly into the blood.
b. The islets contain three major types of cells, alpha, beta, and delta cells
c. The beta cells, constituting about 25 percent of all the cells of the islets, lie mainly in the middle of each islet and secrete insulin and amylin.
d. The alpha cells, about 60 percent of the total, secrete glucagon and the delta cells, about 10 percent of the total, secrete somatostatin.
TLS Online TPP Program

#Question id: 18947

#Unit 13. Methods in Biology

Separation of lipopolysaccharides and high molecular weight polysaccharides using thin layer
TLS Online TPP Program

#Question id: 853

#Unit 1. Molecules and their Interaction Relevant to Biology

In the presence of a large excess of _______ the disulfides (cystines) are fully converted into sulfhydryls (cysteines).