DANYLO HALYTSKYI

LVIV NATIONAL medical UNIVERSITY

DEPARTMENT OF BIOLOGICAL CHEMISTRY

MCQs

in biochemistry

for students of medical, dentistry and pharmaceutical faculty

Lviv – 2012

Prepared by:

Prof. Sklyarov A.Ya., M.D., Ph.D

Prof. Lutsik M.D., M.D., Ph.D

Fomenko I.S., Ph.D

Klymyshin D.O., Ph.D

Nasadyuk C.M., M.D., Ph.D

Editor: prof. Sklyarov A.Ya., M.D., Ph.D.

Reviewed by: prof. Pinyazhko O.R., M.D., Ph.D

prof. Komarytsia J.D., M.D., Ph.D

Foreword

biological chemistry is a fundamental medical discipline. The understanding of the processes of proteins, carbohydrates, lipids and water turnover as well as the role of vitamins, trace elements and regulatory mechanisms in the organism is the background for the interpretation of the laboratory indices in health and disease in clinical practice.

The obtaining of the proper knowledge, based on the use of the different methodological approaches, i.p. test control, is one of the main tutorial elements for the students of the higher educational medical institutions.

Aimed at the improving of the students’ knowledge and the level of their preparation for the practical exercises, modul controls and integral examination “Krok-1”, the department prepared a guide, which according to the program, includes: tests, clinical cases, schemes of chemical transformations on key questions, which are presented in Chapter 13 of the guide. The list of references includes the main guides on biochemistry, accessible in the university library.

The authors hope that the use of this guide will improve the level of students’ knowledge and be helpful in mastering of the learning material.

CONTENTS

	FOREWORD
Section І	Control of the initial level of knowledge. Biochemical constituents of the cell. Methods of biochemical investigations	5
Section II	Enzymes and coenzymes. Regulation of metabolism.	19
Section III	Metabolic pathways and bioenergetics. Tricarboxylic acid cycle. Biological oxidation and oxidative phopshorylation	40
Section IV	Structure and metabolism of carbohydrates	65
Section V	Structure and metabolism of lipids	91
Section VI	Structure and metabolism of amino acids	121
Section VII	Principles of molecular biology and molecular genetics	146
Section VIII	Molecular mechanisms of hormone action on target cells. Biochemistry of hormonal regulation	167
Section IX	Biochemistry of the nervous tissue	191
Section X	Biochemistry of the muscular tissue	202
Section XI	Biochemistry of nutrition	214
Section XII	Functional role of water soluble and fat soluble vitamins in metabolism and providement of cell functions.	227
Section XIII	Biochemistry and pathobiochemistry of blood.	243
Section XIV	Functional and clinical biochemistry of liver tissue. Biotransformation of xenobiotics and endogenous toxic compounds.	257
Section XV	Water and mineral metabolism.	270
Section XVI	Functional role of kidneys in urinogenesis. Normal and pathological constituents of urine	276
Section XVII	Biochemical constituents of connective tissue.	284
Section XVIII	Biochemistry of saliva and tooth tissue	290
Section XIX	Biochemical reactions	306
	References:	310

Section I Control of the initial level of knowledge. Biochemical constituents of the cell. Methods of biochemical investigations.

1. All proteins contain the:

A. Same 20 amino acids

B. Different amino acids

C. 300 amino acids occurring in nature

D. Same 5 amino acids

E. Only a few amino acids

2. Proteins contain:

A. Only L- - amino acids

B. Only D-amino acids

C. D, L-Amino acids

D. Only L- β- amino acids

E. Only D- β- amino acids

3. In proteins the -helix and β-pleated sheet are examples of:

A. Secondary structure

B. Primary structure

C. Tertiary structure

D. Quaternary structure

E. All of these

4. Living cells have the unique ability to synthesize only ___ the form of optical isomer of amino acids due to __:

A. ‘L’ form stereospecific enzymes ‘

B. D’ form, stereospecific enzymes

C. ‘D’ form, DNA

D. ‘L’ form, DNA

E. ‘D’ form, RNA

5. Isoelectric pH of an amino acid is that pH, at which it has a:

A. Nil net charge

B. Negative charge

C. Positive charge

D. None of these

E. All of these

6. A Zwitter ion is one which has in aqueous solution:

A. No electrical charges at all

B. Two positive charges and one negative charge

C. Two negative charges and one positive charge

D. One positive charge and one negative charge

E. One positive charge

7. This amino acid can not have optical isomers:

A. Glycine

B. Histidine

C. Threonine

D. Alanine

E. Arginine

8. The amino acid containing hydroxyl group:

A. Threonine

B. Isoleucine

C. Arginine

D. Alanine

E. Ornithine

9. An aromatic amino acid is:

A. Tyrosine

B. Lysine

C. Taurine

D. Arginine

E. Alanine

10. Primary structure of a protein is formed by:

A. Peptide bonds

B. Hydrogen bonds

C. Disulphide bonds

D. All of these

E. None of these

11. Two amino groups are present in:

A. Lysine

B. Glutamate

C. Leucine

D. Threonine

E. Alanine

12. Branched chain amino acids are:

A. Valine, Leucine and Isoleucine

B. Tyrosine and Tryptophan

C. Glycine and Serine

D. Cysteine and cystine

E. Glutamine and Asparagine

13. The sulphur containing amino acid:

A. Methionine

B. Serine

C. Homoserine

D. Valine

E. Tyrosine

14. Which of the following statement about the peptide bond is true?

A. It is planar

B. It has cis hydrogen and oxygen groups

C. It is a carbon-carbon bond

D. It has rotational freedom

15. An amino acid not found in proteins is:

A. β-Alanine

B. Proline

C. Lysine

D. Histidine

E. Arginine

16. Starch is a:

A. Polysaccharide

B. Monosaccharide

C. Disaccharide

D. Protein

E. None of these

17. Polysaccharides are:

A. Polymers

B. Acids

C. Proteins

D. Oils

E. Fats

18. The general formula of monosaccharides is:

A. CnH₂nOn

B. C₂nH₂On

C. CnH₂O₂n

D. CnH₂nO₂n

E. CnO₂n

19. A polysacchharide which is often called animal starch is:

A. Glycogen

B. galactose

C. Inulin

D. Dextrin

E. Glucose

20. The sugar found in milk is:

A. Lactose

B. Glucose

C. Fructose

D. Galactose

E. Ribise

21. A triose sugar is:

A. Glycerose

B. Ribose

C. Erythrose

D. Fructose

E. Glucose

22. An example of a saturated fatty acid is:

A. Palmitic acid

B. Oleic acid

C. Linoleic acid

D. Erucic acid

E. Arachidonic acid

23. The cholesterol molecule is:

A. Steroid

B. Quinoline derivative

C. Benzene derivative

D. Straight chain acid

E. Amino acid

24. Vitamins are:

A. Accessory food factors

B. Generally synthesized in the body

C. Produced in endocrine glands

D. Proteins in nature

E. Carbohydrates

25. A nucleoside consists of:

A. Purine or pyrimidine base + sugar

B. Nitrogenous base

C. Purine or pyrimidine base + phosphorous

D. Purine + pyrimidine base + sugar +phosphorous

E. Sugar + phosphorous

26. The sugar moiety present in RNA is:

A. Ribose

B. Arabinose

C. Ribulose

D. Deoxyribose

E. Glucose

27. The nitrogenous base present in the RNA molecule is:

A. Uracil

B. Thymine

C. Xanthine

D. Hypoxanthine

E. Methylthymone

28. The sugar found in DNA is:

A. Deoxyribose

B. Ribose

C. Xylose

D. Ribulose

E. Glucose

29. The most active site of protein synthesis is the:

A. Ribosome

B. Nucleus

C. Mitochondrion

D. Cell sap

E. The Golgi complex:

30. A nucleotide consists of:

A. Purine or pyrimidine base + sugar + phosphorous

B. A nitrogenous base like choline

C. Purine or pyrimidine base + sugar

D. Purine or pyrimidine base + phosphorous

E. Sugar + phosphorous

31. A purine nucleotide is:

A. AMP

B. UMP

C. CMP

D. TMP

E. TDP

32. A pyrimidine nucleotide is:

A. CMP

B. AMP

C. GMP

D. IMP

E. ATP

33. The most abundant free nucleotide in mammalian cells is:

A. ATP

B. NAD

C. GTP

D. FAD

E. FMN

34. RNA does not contain:

A. Thymine

B. Adenine

C. Uracil

D. Ribose

E. Phosphorous

35. Genetic code is:

A. Collection of codons

B. Collection of amino acids

C. Collection of purine nucleotide

D. Collection of pyrimidine nucleotide

E. Collection of fatty acids

36. Genetic information of nuclear DNA is transmitted to the site of protein synthesis by:

A. mRNA

B. rRNA

C. tRNA

D. Polysomes

E. DNA

37. Synthesis of DNA is also known as:

A. Replication

B. Duplication

C. Transcription

D. Translation

E. Mutation

38. Nucleic acids are biopolymers, which are formed from the next monomers:

1. Mononucleotides

2. Amino acids

3. Carbohydrates

4. Isoprene units

5. Fatty acids

39. Genetic information flows from:

A. DNA to RNA

B. DNA to DNA

C. RNA to cellular proteins

D. DNA to cellular proteins

E. RNA to DNA

40. Oxidation of which substance in the body yields the most calories:

A. Lipids

B. Glycogen

C. Protein

D. Glucose

E. Vitamins

41. Eukaryotes have defined cells, which exhibit the next structural peculiarity:

1. Genetic information is stored in DNA, organized as nuclear chromatin

2. The cell possess a cell wall

3. The cell contains specific particles, responsible for cell respiration

4. Genetic information is stored in DNA, uniformly distributed throughout the cytoplasm

5. Genetic information is stored in messenger RNA

42. Lysosomes are cellular organelles, which have the following functional significance:

1. Degradation of complex biomolecules (proteins, nucleic acids, oligosaccharides etc.)

2. Production of energy (biosynthesis of ATP)

3. Post-translational modification of proteins

4. Oxygen consumption by the cell (respiration)

5. Cell movement

43. Proteasomes are subcellular particles responsible for the next process in the cell:

A. Hydrolysis of polypeptides and proteins

B. Specific folding of protein polypeptide chain

C. Post-translational modification of proteins

D. Degradation of damaged nucleic acds

E. Degradation of oligosaccharide part of glycoproteins

44. The cellular organelles called “suicide bags” are:

A. Lysosomes

B. Ribosomes

C. Nucleolus

D. Golgi’s bodies

E. Mitochondria

45. The following chemical constituent stores genetic information in the cell:

1. Nuclear DNA

2. Messenger RNA

3. Euchromatin

4. Heterochromatin

5. Ribosomal RNA collected in nucleoli

46. Biosynthesis of protein in the cell takes place in specialized subcellular particles which are called:

1. Ribosomes

2. Nucleosomes

3. Proteasomes

4. Centrosomes

5. Peroxysomes

47. The following substances are cell inclusions except:

A. Centrosome

B. Glycogen

C. Lipids

D. Melanin

E. Vitamins

48. The power house of the cell is:

A. Mitochondria

B. Cell membrane

C. Nucleus

D. Lysosomes

E. Peroxysomes

49. The digestive enzymes of cellular compounds are confined to:

A. Lysosomes

B. Ribosomes

C. Peroxisomes

D. Polysomes

E. Mitochondria

50. In determination of concentration of hormones in blood the next method is routinely used in clinical laboratory investigations:

1. Immunoenzymatic assay

2. Immunoprecipitation

3. Chromatography

4. Spetrophotometry

5. Polarography

51. In determination of protein concentration in blood plasma the next method is the most convenient and most frequently used in laboratory practice:

1. Colorimetry

2. Precipitation by salts of heavy metals

3. Precipitation with strong acids

4. Electrophoresis

5. Polarography

52. The movement of charged particles towards one of the electrodes under the influence of electrical current is:

A. Electrophoresis

B. Molecular sieving

C. Gas liquid chromatography

D. Gel filtration

E. Spectrometry

53. Detection of protein in biological fluids, e.g. in urine, is achieved with the next methodical approach:

1. Precipitation with strong inorganic or organic acids

2. Amino acid analysis after acid hydrolysis of sample.

3. Immunoprecipitation with specific antiserum

4. Determination of optical density at 280 nm

5. Polarimetry

54. Indicate optical method of investigation, which is used in clinical biochemistry:

А. Photocolorimetric

В. Affinity chromatography

С. Salting out

D. Electrophoresis

Е. Immunoenzyme assay

55. The sorting out of molecules according to size and shape may be adapted to protein purification in this technique:

A. Gel filtration chromatography

B. Adsorption chromatography

C. Paper chromatography

D. Electrophoresis

E. Immunoenzyme assay

56. Separation of molecules according to their molecular mass is achieved by the next chromatographic method:

1. Gel filtration chromatography

2. Ion exchange chromatography

3. Absorption chromatography

4. Partition chromatography

5. Affinity chromatography

57. Biuret reaction is specific for:

A. –CONH-linkages

B. –CSNH₂ group

C. –(NH)NH₂ group

D. –SH groups

E. All of these

58. Which of the following techniques purifies proteins:

A. Ion exchange chromatography

B. Photocolorimetry

C. Polarography;

D. Fluorescent analysis

E. Immunoenzyme assay

59. The solubility of most proteins is lowered at high salt concentrations process called:

A. Salting out process

B. Salting in process

C. Isoelectric focussing

D. None of these

60. The degradative processess are categorized under the heading of:

A. Catabolism

B. Anabolism

C. Metabolism

D. Amphibolism

E. None of the above