Many bacterial responses are controlled by two component regulatory systems. What will happen at the high concentration of glutamine and at the low concentration of glutamine?

a) At high concentrations glutamine binds to a sensor domain of NtrB conformational change in the protein that inhibits its histidine kinase activity

b) NtrC phosphorylation takes place causes a conformational change in NtrC that unmasks the NtrC DNA-binding domain so that it can bind to the glnA enhancers

c) At the same time, the regulatory domain of NtrC blocks its DNA-binding domain from binding the glnA enhancers

d) At low concentrations of glutamine dissociates from the sensor domain in the NtrB protein, leading to activation of a histidine kinase transmitter domain

Which of the following given combination is correct?

#Question id: 617

#Unit 1. Structure and Function of Biomolecules

Compare the two reaction coordinate diagrams below and select the answer that correctly describes their relationship.  In each case, the single intermediate is the ES complex.

#Question id: 618

#Unit 1. Structure and Function of Biomolecules

 In the following diagram of the first step in the reaction catalyzed by the protease chymotrypsin, the process of general base catalysis is illustrated by the number ________, and the process of covalent catalysis is illustrated by the number _________.

#Question id: 619

#Unit 1. Structure and Function of Biomolecules

The benefit of measuring the initial rate of a reaction V0 is that at the beginning of a reaction:

#Question id: 620

#Unit 1. Structure and Function of Biomolecules

Which of the following statements about a plot of V0 vs. [S] for an enzyme that follows Michaelis-Menten kinetics is false?

#Question id: 621

#Unit 1. Structure and Function of Biomolecules

Michaelis and Menten assumed that the overall reaction for an enzyme-catalyzed reaction could be written as Using this reaction, the rate of breakdown of the enzyme-substrate complex can be described by the expression:

#Question id: 622

#Unit 1. Structure and Function of Biomolecules

An enzyme-catalyzed reaction was carried out with the substrate concentration initially a thousand times greater than the Km for that substrate.  After 9 minutes, 1% of the substrate had been converted to product, and the amount of product formed in the reaction mixture was 12 micromol.  If, in a separate experiment, one-third as much enzyme and twice as much substrate had been combined, how long would it take for the same amount (12 micromol) of product to be formed?