The titration curve of alanine shows the ionization of two functional groups with pKa values of 2.34 and 9.69, corresponding to the ionization of the carboxyl and the protonated amino groups, respectively. The titration of di-, tri-, and larger oligopeptides of alanine also shows the ionization of only two functional groups, although the experimental pKa values are different. The trend in pKa values is summarized in the table. Which of the following is a reason for this shift in pK values

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#Question id: 15638

#Unit 13. Methods in Biology

You have isolated two mutations that show decreased expression of the Lac operon. However, unlike like the promoter mutations, these mutations don’t respond to the inducer IPTG. These mutations, designated Lac3– and Lac4–, are evaluated for the quantity of ß-galactosidase and permease activity expressed with or without IPTG:

 

Mapping experiments reveal that Lac3– and Lac4– are different short deletions located in the region before the start of the LacZ gene. Given the data shown above suggest which genetic element(s) in addition to part of the promoter has been deleted in each mutant. 

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#Question id: 2203

#Unit 2. Cellular Organization

Parietal cells acidify the stomach contents while maintaining a neutral cytosolic pH by: 

a. exporting “excess” cytosolic OH– as HCO3–.
b. exchanging HCO3– for Cl–.
c. preserving electroneutrality by accompanying the movement of each Cl– ion into the stomach lumen by a K+.
d. the excess K+ ions pumped inward by the H+/K+ ATPase are returned to the stomach lumen, thus maintaining the normal intracellular K+ concentration.
Which of the following combination is correct?

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#Question id: 4280

#Unit 3. Fundamental Processes

Translocation of proteins into mitochondria and chloroplasts is characterized by

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#Question id: 5940

#General Aptitude

The day on April of a year is the same day on what date of the same year?

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#Question id: 29435

#Unit 6. System Physiology – Plant

Flavonoid's compound release by host plant are given match the following