According to the Switching mechanism, monomeric G proteins exist in two states. Match the following states (Column I) with correct mechanism (Column II).

Column I	Column II
A. “ON” state	i. switch I and switch II, are bound to the terminal γ phosphate of GTP through interactions with the backbone amide groups of conserved threonine and glycine residues.
B. “OFF” state	ii. GTPase-activating proteins
	iii. guanine nucleotide exchange factor
	iv. Due to the removal of the γ phosphate by GTPase-catalyzed hydrolysis causes switch I and switch II to relax into a different conformation

#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?

#Question id: 546

#Unit 1. Molecules and their Interaction Relevant to Biology

Enzymes are potent catalysts because they: