Biochemistry Answers

Which of the following statements is NOT valid for RNA biosynthesis? (select one) 

a. RNA synthesis is performed by nucleophilic attack of the 3 'hydroxyl group of the growing chain on the α-hosphate group of the newly introduced nucleotide 

b. RNA synthesis takes place in the 3 ' to 5' direction 

c. DNA synthesis requires a primer and RNA polymerase does not 

d. RNA polymerase includes uridine in the polynucleotide chain instead of thymidine 

e. promoters in RNA synthesis play a similar role as the onset of replication in DNA synthesis 

Transmission is a process in which (select one) 

a. the α-amino group is oxidized 

b. the α-amino group is removed 

c. the carboxyl group is removed from the amino acid 

d. amino acid interacts with α-oxo acid 

e. polymerize amino acids 

In the liver, glucagon activates (select one) 

a. Gluconeogenesis and glycogenolysis 

b. Gluconeogenesis and protein phosphatase 

c. Glycolysis and ketogenesis 

d. Glycolysis and glycogen synthesis 

e. Gluconeogenesis and glycogen synthesis 

Which of the following statements are incorrect? (select one or more) 

a. Non-competitive inhibitors usually bind to the enzyme irreversibly 

b. In competitive inhibition, the substrate competes with the enzyme upon binding to the inhibitor 

c. Competitive inhibitors are similar in structure to substrates 

d. Non-competitive inhibition is observed when the inhibition cannot be removed by adding large amounts of substrate 

e. In competitive inhibition, the substrate and the inhibitor compete for the active site of the enzyme 

Which of the following properties are common to NAD and NADPH? (select one) 

a. They are interchangeable as cofactors of dehydrogenases 

b. Both easily cross the mitochondrial membrane 

c. Both contain two ribose residues, a nicotinamide ring, the nitrogen base adenine and phosphoanhydrides 

d. They have the same redox potential 

e. Both have the same total charge at pH 7 

Which of the following statements best explains the hyperchromatism of DNA? (select one) 

a. the shift of UV absorption to longer wavelengths during denaturation 

b. increase in absorbance at 260 nm after complementary chain coupling and double chain formation 

c. the shift of UV absorption to longer wavelengths after complementary connection of the two chains 

d. the shift of UV absorption to shorter wavelengths during hydrolysis 

e. increase in absorbance at 260 nm after denaturation and chain separation 

Phosphorylation at substrate levels in TAC is the reaction catalyzed by: (select one) 

a. aconitase 

b. isocitrate dehydrogenase 

c. malate dehydrogenase 

d. succinate dehydrogenase 

e. succinate thiokinase 

In mitochondrial electron transport chains, NADH-reducing equivalents are transported by NADH dehydrogenase to: (select one) 

a. coenzyme Q 

b. cytochrome c 

c. cytochrome b 

d. FAD of succinate dehydrogenase 

e. cytochrome a / a3

Which of the following statements is valid for the enzyme complexes of electron transport chains? (select one or more) 

a. they are integral membrane proteins localized in the inner mitochondrial membrane 

b. they cannot be isolated from each other in a functional form 

c. have similar absorption spectra of visible light 

d. interact with each other via mobile electronic carriers 

e. they are localized in the mitochondrial matrix 

The two substrate phosphorylation reactions in glycolysis include (select one) 

a. glucose-6-phosphate and fructose-6-phosphate 

b. 1,3-bisphosphoglycerate and phosphoenolpyruvate 

c. dihydroxyacetone phosphate and 2-phosphoglycerate 

d. glyceraldehyde-3-phosphate and phosphoenolpyruvate 

e. 1,3-bisphosphoglycerate and 2-phosphoglycerate