When electrons flow through the electron transport system from NADH to oxygen, what is the sequence of molecules through which they move?
A. complex I, coenzyme Q, complex III, complex IV, O2
B. complex II, coenzyme Q, complex III, complex IV, O2
C. complex I, cytochrome c, complex III, coenzyme Q, complex IV, O2
D. complex I, coenzyme Q, complex IV, cytochrome c, O2
E. complex I, coenzyme Q, complex III, cytochrome c, complex IV, O2
The four most abundant chemical elements in living systems are:
A. hydrogen, carbon, nitrogen and oxygen
B. sodium, potassium, nitrogen and sulfur
C. sodium, potassium, carbon and oxygen
D. hydrogen, oxygen, sulfur and phosphorus
E. carbon, nitrogen, oxygen and potassium
A common feature of serine proteases is the catalytic triad consisting of a nucleophile, a general base and an acid. In chymotrypsin these amino acid residues are ______, _______, and ______ respectively.
A. histidine, glutamine, arginine
B. serine, glycine, aspartic acid
C. serine, histidine, aspartic acid
D. tryptophan, serine, proline
Which of the following amino acid residues are often involved in proton transfers in enzyme-catalyzed reactions?
A. glutamine, asparagine, lysine, tyrosine
B. histidine, aspartate, serine, cystesine
C. serine, tyrosine, arginine, cystesine
D. histidine, aspartate, glutamate, arginine, lysine
E. histidine, aspartate, lysine, serine
Protein kinases add a phosphoryl group to the -OH group of a _____, ______, or ______ residue f the target protein.
A. serine, tyrosine, threonine
B. tyrosine, proline, arginine
C. serine, cysteine, threonine
D. histidine, cysteine, methionine