Е. Whatever part of polypeptide chain of enzyme molecule.

10. As cofactors of enzymes the most frequently met are the next compounds:

A. Vitamins, modified by cell enzymes (vitamin derivatives)

B. Native vitamins

C. Hormons, e.g.thyroxine

D. Carbohydrates

E. Polynucleotides

11. Nonprotein part of complex (conjugated) enzyme is called as:

A. Coenzyme

B. Holoenzyme

C. Apoenzyme

D. Allosteric activator

E. Allosteric suppressor

12. Chose the correct statement about allosteric site of enzyme:

1. It modulates reversibly enzymatic activity after binding with ligand

2. It is identical with active center

3. It serves for attachment of enzyme to biomembrane

4. It irreversibly inhibits enzymatic activity after binding with ligand

5. It induces chemical modification of enzyme molecule

13. The active site of an enzyme is formed by:

1. R group of amino acids

2. NH₂ group of amino acids

3. CO group of amino acids

4. Sulphur bonds which are exposed

5. Peptide bonds

14. Coenzymes are:

1. Heat stable, dialyzable, non protein organic molecules

2. Soluble, colloidal, protein molecules

3. Structural analogue of enzymes

4. Different forms of enzymes

5. Inorganic catalists

1. Allosteric suppressor

15. Coenzymes combine with:

1. Apoenzymes

2. Proenzymes

3. Holoenzymes

4. Antienzymes

5. Cofactors

16. Active centers in nonconjugated (simple) enzymes, e.g.trypsin, are formed by the next constituents of enzyme molecule:

1. Amino acid side chains only

2. Peptide bonds between selected amino acids

3. Nucleotides

4. Carbohydrates

5. Phospholipids

17. Chose the amino acid, which is frequently involved in formation of active center in different enzymes.

1. Histidine

2. Leucine

3. Proline

4. Valine

5. Glycine

18. Which from the listed below is coenzyme?

1. All of these

2. ATP

3. Vitamins B and C

4. CoQ and CoA

5. Thiamine

19. How are called enzymes which catalyze the same reaction, are of the same origin but differ in chemical properties?

1. Izoenzymes

1. Apoenzyme

2. Coenzyme

3. Holoenzyme

4. Zymogen

20. Multiple forms of the same enzymes are known as:

1. Isoenzymes

2. Zymogens

3. Proenzymes

4. Pre-enzymes

5. Coenzymes

21. Enzymes activity is controlled by

1. All of these

2. pH of the solution

3. Temperature

4. Concentration of the enzyme

5. Concentration of the substrate

22. Boiling destroys the activity of enzyme irreversibly due to the next process:

1. Change in conformation of enzyme molecule

2. Cleavage of peptide bonds in polypeptide chain of enzyme.

3. Cleavage of disulphide bonds in enzyme molecule

4. Cleavage of ionic bonds in enzyme molecule

5. Formation of intramolecular or intermolecular cross-links in enzyme molecule

23. In humans most enzymes have an optimal temperature of action at:

1. 37 ^oC

2. 0 ^oC

3. 20 ^oC

4. 30 ^oC

5. 100 ^oC

24. What happens with enzymes at 90 ^oC?

1. Denaturation

2. Hydrolysis

3. Alteration of primary structure

4. Alteration of tertiary structure

5. Tight binding of substrate in active site

25. The pH optima of most of the enzymes is:

1. Between 6 and 8

2. Between 1 and 3

3. Between 4 and 6

4. Between 8 and 12

5. Above 12

26. Pepsin has the next pH optimum for enzymatic activity:

1. pH 1,5

2. pH 5,1

3. pH 7,5

4. pH 8,0

5. pH is non significant

27. Trypsin exhibits maximal catalytic activity at the next pH value:

A. pH 7,5

B. pH 5,1

C. pH 2,5

D. pH 9,5

E. pH is non significant

28. Chose from listed below enzymes, ONE which represents class hydrolases:

1. Pepsin

2. Aldolase

3. Glucokinase

4. Phenol oxidase

5. ATP synthase

29. Enzymes, providing polysaccharide hydrolysis are defined as:

1. Glycosidases

2. Lipase

3. Phosphatase

4. Catalase

5. Proteases

30. The first position in classification of enzymes is occupied by:

1. Oxidoreductases

2. Transferases

3. Isomerases

4. Hydrolases

5. Ligases

31. The fourth position in classification of enzymes is occupied by:

1. Lyases

2. Transferases

3. Isomerases

4. Hydrolases

5. Ligases

32. The code number of each individual and well characterized enzyme contains the next ranges of figures:

1. Four

2. Two

3. Three

4. Five

5. Six

33. Chose from list below enzymes, which exhibits specificity to peptide bonds:

1. Chymotrypsin

2. Urease

3. Alcohol dehydrogenase

4. Arginase

5. Cellulase

34. What type of reactions presented below is catalyzed by hydrolases?

1. A-B + H₂O = A-OH + B-H

2. AH₂ + B = A + BH₂

3. A+B+ATP= A-B + ADP + P_i

4. A-B = A + B

5. A-R-B = A-B-R

35. What type of presented below reactions is catalyzed by dehydrogenases?

1. AH₂ + B = A + BH₂

2. A+B+ATP= A-B + ADP + P_i

3. A-B + H₂O = A-OH + B-H

4. A-B = A + B

5. A-R-B = A-B-R

36. The best example of extracellular enzymes (exoenzyme) is:

1. Digestive enzymes

2. Nucleases

3. Succinic dehydrogenase

4. Malatedehydrogenase

5. None of these

37. The substrate for amylase is:

1. Starch

2. Cane sugar

3. Lactose

4. Ribose

5. Maltose

38. In cell, digestive enzymes are found mainly in:

1. Lyzosomes

2. Mitochondria

3. Ribosomes

4. Nucleus

5. Vacuoles

39. A mitochondrial marker enzyme is:

1. Succinate dehydrogenase

2. Aldolase

3. Amylase

4. Pyruvate dehydrogenase

5. DNA-polymerase

40. The third position in classification of enzymes is occupied by:

A. Hydrolases

B. Transferases

C. Lyases

D. Isomerases

E. Ligases

41. In human saliva there is an enzyme able to hydrolyze the α[1→4] glucosidic bonds in the molecule of starch. Name this enzyme:

1. α-Amylase

2. Phosphatase

3. Fructofuranosidase

4. β-Galactosidase

5. Lysozyme

42. In the cell, enzymes are located in subsequent organelles, providing their specific functioning. Note enzymes located in lysosomes.

1. Cathepsins and glucosaminidase

2. Fatty acid synthesis enzyme complex

3. Enzymes of protein biosynthesis

4. Enzymes of urea synthesis

5. Glycogen synthetase and branching enzyme

43. Cytochrome c participates in transport of electrons in respiratory chain of the cell and is located in the next cellular compartment:

1. Mitochondria

2. Nucleus

3. Cytoplasm

4. Golgi vesicles

5. Lysosomes

44. In a patient was detected disorder in digestion of protein in stomach and small intestines. What group of enzymes may cause this disorder?

А. Proteinases

В. Amylase

С. Lipase

D. Lyases

Е. Aminotransferases

45. Chose from list below enzymes located in nucleus:

1. RNA polymerases

2. Enzymes of protein biosynthesis

3. Enzymes of tricarboxylic acid cycle

4. Cathepsins and glucosaminidase

5. Glycogen synthetase and branching enzyme

46. The enzymes of the citric acid cycle are located in:

1. Mitochondrial matrix

2. Extramitochondrial soluble fraction of the cell

3. Nucleus

4. Endoplasmic reticulum

5. Lysosomes

47. Chose from list below, enzyme belonging to class of hydrolases:

1. Thrombin

2. Lactate dehydrogenase

3. Glucokinase

4. Phenol oxidase

5. Aldolase

48. Chose from listed below enzymes, ONE which exhibits specificity to peptide bonds:

A. Chymotrypsin

B. Urease

C. Alcohol dehydrogenase

D. Arginase

E. Cellulase

49. Activity of multienzyme complexes is regulated by the next type of regulation:

1. Feedback inhibition

2. Catabolic repression

3. Limited proteolysis

4. Non competitive inhibition

5. Competitive inhibition

50. Proenzymes:

1. All of these

2. Chymotrysinogen

3. Pepsinogen

4. Proelastase

5. Trysinogen

51. An allosteric modulator influences enzyme activity by:

1. Binding to a site on the enzyme molecule distinct from the catalytic site

2. Competing for the catalytic site with the substrate

3. Changing the nature of the product formed

4. Changing the specificity of the enzyme for its substrate

5. Covalent modification of enzyme

52. In active center of enzymes which catalyze hydrolysis of substrate (hydrolases) usually is present the next amino acid residue:

1. Histidine

2. Leucine

3. Phenylalanine

4. Proline

5. Valine

53. In active center of enzyme very frequently is present side chain of the next amino acid:

1. Histidine

2. Leucine

3. Phenylalanine

4. Proline

5. Valine

54. Activity of many enzymes depends from the presence of free thiol groups in active center. What amino acid residue provides presence of these groups in enzyme molecule?

1. Cysteine

2. Lysine

3. Tryptophan

4. Methionine

5. Serine

55. Michaelis-Menten constant (K_m) reflects the next property of enzyme:

1. Affinity to substrate

2. Thermolability

3. Sensitivity to pH of medium

4. Affinity to a product of reaction

5. Sensitivity to competitive inhibitors

56. Michaelis-Menten constant corresponds to: