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: 540

#Unit 1. Molecules and their Interaction Relevant to Biology

During strenuous exercise, the NADH formed in the glyceraldehyde 3-phosphate dehydrogenase reaction in skeletal muscle must be reoxidized to NAD+ if glycolysis is to continue.  The most important reaction involved in the reoxidation of NADH is:

#Question id: 541

#Unit 1. Molecules and their Interaction Relevant to Biology

The overall △G for glycolysis is -72 kJ/mol in erythrocytes. Which statement below is true?

A) The value of △G0ʹ is also -72 kJ/mol since the cytosol pH is close to 7.

B) The free energy of glycolysis is found as the sum of the standard free energy changes for

the individual pathway reactions.

C) The negative sign of △G shows that this pathway will proceed toward product (pyruvate) under normal cellular conditions.

#Question id: 542

#Unit 1. Molecules and their Interaction Relevant to Biology

Hamsters love to run on exercise wheels. Prolonged running at a high rate of speed requires ATP. Could a hamster with a defective gene for the enzyme lactate dehydrogenase meet the extra ATP demand for prolonged, fast wheel-running by maintaining a high rate of glycolysis? Why or why not?

#Question id: 543

#Unit 1. Molecules and their Interaction Relevant to Biology

If glucose labeled with 14C at C^-1 (the aldehyde carbon) were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:

#Question id: 544

#Unit 1. Molecules and their Interaction Relevant to Biology

One of the enzymes involved in glycolysis, aldolase, requires Zn2+ for catalysis. Under conditions of zinc deficiency, when the enzyme may lack zinc, it would be referred to as the:

#Question id: 545

#Unit 1. Molecules and their Interaction Relevant to Biology

Which one of the following is not among the six internationally accepted classes of enzymes?