Biochemistry Answers

Which of the following statements apply to globular proteins (select one or more) 

a. active center is formed at the level-secondary structure 

b. regulatory centers are formed at the level of the quarterly structure 

c. when the tertiary structure is disturbed, partial and complete loss of biological properties occurs 

d. subunits in quaternary proteins bind to covalent bonds 

e. active center is formed at the level-tertiary structure 

2,3-BPG (2,3-bisphosphoglycerate) is an intermediate in the reaction catalyzed by phosphoglycerate mutase. Erythrocytes need minimal amounts of 2,3-BPG because: (select one or more) 

a. involved in the conversion of 3-phosphoglycerate to 2-phosphoglycerate 

b. involved in the formation of 1,3-bisphosphoglycerate 

c. fatty acid synthase regulator 

d. is a negative effect of hemoglobin function 

e. ATP synthase regulator 

Which of the following pairs of amino acids has a negatively charged side chain at pH 8.0? (select one) 

A. asparagine and glutamine 

B. leucine and glycine 

C. histidine and lysine 

D. aspartate and glutamate 

An alcoholic in a state of hypoglycaemic coma was admitted to Pirogov. Since alcoholics usually suffer from malnutrition, Dr. Ivanov performs a biochemical test. Which of the following enzymes should you test for thiamine deficiency? (select one) 

A. UDP-galactose epimerase 

B. transaldolase 

C. aldolase 

D. glucose-6-phosphate dehydrogenase 

E. transketolase 

Which of the following statements about Michaelis-Menten kinetics is true provided that the substrate concentration is equal to Km: (select one or more) 

A. 50% of enzyme molecules are bound to the substrate 

B. the reaction rate is equal to half the Vmax 

C. the reaction rate is equal to Vmax 

D. the reaction rate does not depend on the substrate concentration 

E. the enzyme is completely saturated with substrate 

What is the role of carbohydrates in nature (select one or more) 

a. they are a component in the structure of important coenzymes 

b. they are conjugated to a number of proteins and lipids 

c. they are an energy source for animals and plants 

d. they are the main structural component of animal cells 

e. they are a component of nucleic acids 

Which of the following lipids is involved in signal transduction (select one) 

a. phospholipase A2 

b. phosphatidyl glycerol 

c. phosphatidyl choline 

d. phosphatidyl serine 

e. plasminogen activator 

f. phosphatidyl inositol 4,5-bisphosphate

Which of the following statements concerning the cases in which glycogen phosphorylase and glycogen synthase are phosphorylated under the action of cAMP-dependent protein kinase? (select one) 

a. one process is direct and the other is carried out by a cascade mechanism such as glycogen phosphorylase is activated and glycogen synthase is inactivated 

b. one process is direct and the other is carried out by a cascade mechanism 

c. one process is direct and the other is carried out by a cascade mechanism and both enzymes are inactivated 

d. both processes are performed by a cascade mechanism as glycogen phosphorylase is activated and glycogen synthase is inactivated 

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 

What is the role of sodium dodecyl sulfate (SDS) in the isolation of plasmid DNA (select one) 

a. helps dissolve DNA 

b. binds to DNA and despiralizes it 

c. binds divalent ions and inhibits DNA 

d. precipitates RNA 

e. denatures cellular proteins and helps to lyse the cell membrane