Which of the following is a precursor of protoporphyrin?

A. Histidine

B. Leucine

*C. Glycine

D. Proline

E. Alanine

Carbon monoxide in the body is synthesized during

A. Synthesis of carnitine

*B. Breakdown of hemoglobin

C. Ribosomal protein synthesis

D. Gluconeogenesis

E. Anaerobic glycolysis

Which of the following is seen in obstructive jaundice?

A. Excess of bile salts in the urine

B. Excess of urobilinogen in urine

*C. Excess of conjugated serum bilirubin

D. Excess of bile salts in feces

E. Excess of stercobilinogen in urine

True regarding conversion of deoxyhemoglobin to oxyhemoglobin in lungs is:

A. Binding of oxygen causes increased binding of 2,3-DPG

B. One mole of deoxyhemoglobin binds two moles of 2,3-DPG

*C. Binding of oxygen causes release of proton

D. pH of blood has no affect on the binding of oxygen

E. Binding of oxygen causes release of phosphate

Bilirubin glucuronide in the urine in the absence of urobilinogen suggests:

*A. Obstructive jaundice

B. Hepatocellular jaundice

C. Congenital erythropoetic porphyria

D. Porphyria cutanea tarda

E. Hemolytic jaundice

Name the hemoglobin derivative whose content is increased under carbon monoxide poisoning:

A. Bilirubin IX

B. 1,25-dihydroxy cholecalciferol

C. Carbhemoglobin

*D. Carboxyhemoglobin

E. Para-amino benzoic acid

Bilirubin is produced from:

A. Uric acid

*B. Haemoglobin

C. Stercobilinogen

D. Albumin

E. Glucose

Bilirubin is produced from:

A. Uric acid

B. Glucose

*C. Haemoglobin

D. Albumin

E. Stercobilinogen

Unloading of oxygen to tissue cells by oxy- Hb is assisted by:

*A. All proposed

B. 2-3 diphosphoglycerate

C. Low PO₂ and high PCO₂ in tissues

D. Bohr-affect

E. None of the proposed

Porphyrin is formed by joining together four pyrrole rings by means of _?___bridges:

A. Propylene

B. Hydroxy

C. Hydrogen

D. Phosphate

*E. Methylene

Which of the following can be a homologous substitution for N-terminal valine (6) in beta-subunits of hemoglobin to form hemoglobin S?

A. Alanine

B. Lysine

C. Isoleucine

*D. Glutamic acid

E. Phenylalanine

Porphobilinogen in urine produces pink color with:

*A. Ehrlich’s aldehyde reagent

B. Benedict’s reagent

C. Biuretic reagent

D. Fouchet’s reagent

E. Sodium nitroprusside

What color compound may be produced across hemoglobin degradation in the spleen of humans:

A. Urea

B. Uric acid

C. UDP-glucuronic acid

D. Stercobilinogen

*E. Biliverdin

Patients having obstructive jaundice do not excrete this at all in urine:

A. Glycocholate

B. Urate

C. Urea

D. Bilirubin

*E. Urobilionogen

Heme synthesis is regulated by feedback mechanism. Choose the 5-aminolevulinate synthetase allosteric inhibitor:

*A. Heme

B. Porphobilinogen

C. Vitamin C

D. Protoporphyrin IX

E. Coproporphyrin

Heme to bilirubin conversion is carried out by

A. Heme dehydrogenase

B. Heme hydrolase

*C. Heme oxygenase

D. Heme isomerase

E. Heme reductase

Name blood plasma index whose content is increased mainly under condition of hemolytic anemia in patient:

A. Uric acid

*B. Unconjugated bilirubin

C. Conjugated bilirubin

D. Free amino acids

E. Urea

Bilirubin indexes may be absolutely identical in cases of hepatic and obstructive jaundices. Choose the test that can confirm the liver parenchyma damage:

A. Determination of ketone bodies in the urine

B. Determination of glucose in the urine

C. Determination of the glucose concentration in the blood plasma

*D. Determination of alanine aminotransferase activity in the blood plasma

E. Uric acid determination in blood plasma

Patients having obstructive jaundice do not excrete this at all in urine:

A. Bilirubin

B. Glycocholate

*C. Urobilinogen

D. Urea

E. Urate

The enzymes that synthesize delta-amino levulinate (from succinyl CoA and glycine) and produce pyruvate (from cysteine) are both:

A. Metalloproteins

B. NADH dependent

*C. Pyridoxal phosphate dependent

D. Biotin dependent

E. Flavoproteins

Which of the following membrane has the highest protein content per gram of tissue:

*A. Inner mitochondrial membrane

B. Plasma membrane

C. Myelin sheath

D. Nuclear membrane

E. Outer mitochondrial membrane

In a human genome project scientists notice, that one strand of the DNA molecule contains 20 thymine (T), 25 cytosine (C), 30 guanine (G) and 22 adenine (A) residues. How many of each of the bases is found in complete double-stranded molecule

A. T=40, C=50, G=60, A=44

B. T=22, C=30, G=25, A=20

C. T=44, C=60, G=50, A=40

D. T=42, C=50, G=60, A=42

*E. T=42, C=55, G=55, A=42

Point out the role of proteins located in the cellular membrane:

A. Glucose transport channel

B. To be receptor for hormone

C. Ion transport channel

D. Enzyme

*E. All the positions are right

Nowadays about 50 minor bases have found in the t-RNA structure besides the main four nitrogenous bases. Choose the minor nitrogenous base:

*A. Dihydrouracil

B. Cysteine

C. Uracil

D. Adenine

E. Cytosine

The major driving force for the formation of membrane bilayer is

A. Hydrophobic interactions

B. Hydrogen bonding

C. Van der Waals forces

D. Electrostatic attractions

*E. All proposed

Chargaff rule states that

A. A+T=G+C

B. A=U=T=G=C

C. None of the above

*D. A/T=G/C

E. A+G=T+C

Which of the following is responsible for increasing the fluidity of the membrane:

A. Palmitic acid

*B. Linoleic acid

C. Cholesterol ester

D. Cholesterol

E. Stearic acid

Triple hydrogen bonds are found between which base pairs:

*A. C-G

B. C-U

C. A-G

D. C-T

E. A-T

Point out products of guanosine degradation in tissues formed at first reaction:

A. Ribose, phosphate

B. Guanine, pyrophosphate

*C. Guanine, ribose-5-phosphate

D. Guanine, phosphate

E. Ribose, pyrophosphate

Biological membrane contains all the following except

A. Prostaglandins

B. Cholesterol

*C. Steroid receptors

D. Cytochrome P450

E. Na⁺/K⁺-ATPase

Choose the correct definition of the term “modified base”:

A. Purine or pyrimidine attached to ribose

B. A purin or pyrimidine attached to a sugar by O-glycoside linkage

C. A nitrogen containing ring other than a purine or pyrimidine that is part of a nucleotide

*D. A purine or pyrimidine that has been altered

E. Purine or pyrimidine attached to deoxyribose

Which one of the following is the complementary

sequence of 5’-TTAAGCTAC-3’?:

A. 5’CCGGATCGT3’

*B. 5’AATTCGCATG3’

C. 5’GTAGCTTAA3’

D. 5’CATGCGAATT3’

E. 5’TTAAGCGTAC3’

Nucleic acids have acid properties due to the presence of residues in their structure:

A. Deoxyribose

*B. Phosphoric acid

C. Adenosine

D. Ribose

E. Guanine

Deoxyribose is different from ribose by:

A. The presence of hydroxyl group at the third carbon atom

B. The presence of amino group

C. The presence of hydroxyl group at the second carbon atom

D. The quantity of carbon atoms

*E. The absence of hydroxyl group at the second carbon atom

Due to complete hydrolysis of DNA, we will get all of the following except:

*A. Adenosine

B. Deoxyribose

C. Purine bases

D. Pyrimidine bases

E. Phosphoric acid

At the physiological pH the DNA molecules are:

A. Uncharged

B. Neutral

*C. Negatively charged

D. Positively charged

E. Amphipathic

According to the model of double DNA helix that was suggested by Watson and Greek, it was astablished that one of chains would not be lost during replication and the second chain would be synthesized complementary to the first one. What way of replication is it?

A. Dispersed

*B. Semicomservative

C. Conservative

D. Analogous

E. Identical

The basic protein, which functions in the packaging of DNA in chromosomes, is:

A. Hyaluronic acid binding protein

B. Collagen type V

C. Fibrinogen

D. Collagen type I

*E. Histone

Choose the qualitative reaction on carbohydrate residue of nucleic acids:

A. Barfed`s reaction

B. Millon`s reaction

*C. Diphenylamine test

D. Biuretic reaction

E. Molybdenic test

Membrane fluidity is increased by increased content of:

A. Cholesterol

B. Stearic acid

*C. Linoleic acid

D. Lauric acid

E. Palmitic acid

The UMP degradation in human tissues is associated with formation of:

*A. Beta-alanine

B. Beta-aminoisobutyric acid

C. Uric acid

D. Aspartic acid

E. Inosinic acid

A 42-year-old man suffering from gout has increased level of urinary acid in blood. Allopurinol was prescribed to decrease the level of urinary acid. Competitive inhibitor of what enzyme is allopurinol?

A. Hypoxanthine phosphoribosiltransferase

B. Adenosine deaminase

C. Adenine phosphoribosiltransferase

D. Guanine deaminase

*E. Xanthine oxidase

Call, please, special synthesis that may be considered as the way for ammonia neutralization in humans:

A. NAD synthesis

B. Protein synthesis

*C. UMP synthesis

D. Ammonia salts formation

E. AMP synthesis

Severe combined immunodeficiency disease is associated with deficiency of :

A. Myeloperoxidase

*B. Adenosine deaminase

C. HGPRTase

D. DNA polymerase III

E. Glucose-6-phosphatase

A gout is developed in patients when the activity of certain enzyme of purine nucleotide de novo synthesis is higher (genetic defect of enzyme) then normal. Point out it:

A. 5’-nucleotidase

B. Adenylsuccinate lyase

*C. PRPP aminotransferase

D. Adenylic acid deaminase

E. Adenylate cyclase

Increased serum uric acid levels occur in:

A. Von Gierke`s disease

*B. All proposed

C. Disturbances of PRPP synthase regulation

D. Leukemia

E. Lesh-Nyhan syndrome

Point out the amino acid used both in AMP and UMP de novo synthesis:

A. Alanine

*B. Aspartic acid

C. Inosinic acid

D. Glycine

E. Glutamic acid

Beta-alanine is a degradation product of:

A. Adenosine

B. Albumin

C. Guanylate

D. Thymidylate

*E. Uridylate

Terminal product of purine metabolism in non-primate mammals is:

A. Ammonia

B. Carbon dioxide and water

C. Uric acid

D. Urea

*E. Allantoin

The pyrimidine nucleotide synthesis features are all right except:

A. Synthesis starts with the aspartic acid

*B. All the UMP nitrogen atoms are got from ammonia molecules

C. The initial substrate (carbamoyl phosphate) may be formed from glutamine, CO₂ with ATP use

D. Carbamoyl-phosphate synthase II is activated by PRPP

E. Phosphoribosyl pyrophosphate is used

A doctor administered allopurinol to a 26-year-old young man with the symptoms of gout. What pharmacological action of allopurinol ensures therapeutical effect?

A. By general anti-inflammatory effect

*B. By inhibiting of uric acid formation

C. By inhibiting of leucocyte migration into the joint

D. By general analgetic effect

E. By increasing of uric acid excretion

Point out the index, whose concentration is determined in the blood plasma of patients with gout:

*A. Uric acid

B. Urea

C. Beta-Aminoisobutyric acid

D. Beta-Alanine

E. Alpha-Alanine

An oncological patient was administered methotrexate. With the lapse of time the target cells of the tumour lost sensitivity to the preparation. We can observe changes in the gene expression of the following enzyme:

A. Folate oxidase

B. Desaminase

C. Thiaminase

D. Folate decarboxylase

*E. Dihydrofolate reductase

A gout is developed in patients when the activity of certain enzyme of purine nucleotide de novo synthesis is higher (genetic defect of enzyme) then normal. Point out it:

A. Adenylic acid deaminase

B. Adenylate cyclase

*C. PRPP aminotransferase

D. 5’-nucleotidase

E. Adenylsuccinate lyase

The pyrimidine nucleotide UMP degradation end product in human organism is:

A. Beta-aminoisobutyric acid

B. Uric acid

C. Inosinic acid

D. Aspartic acid

*E. Beta-alanine

What enzyme deficiency will develop in a young male X-linked recessive disorder with hyperuricemia and mild retardation?

A. Hypoxanthine phosphoribosyl oxidase deficiency

*B. Hypoxanthine phosphoribosyltransferase deficiency

C. Branch chain amino acids metabolites deficiency

D. Homogentisate oxidase defective enzymes

E. Phenylalanine hydroxylase deficiency

Point out the vitamin that is actively used in the purine and pyrimidine nucleotide de novo syntheses:

A. Linolenic acid

B. Ascorbic acid

C. Pangamic acid

*D. Folic acid

E. Pantothenic acid

Allopurinol is a drug used in the gout treatment. Point out the enzyme of purine nucleotide metabolism that is inhibited by it:

A. Phosphoribosyl pyrophosphate synthetase

B. Phosphoribosyl aminotransferase

C. 5’-nucleotidase

D. Adenosine deaminase

*E. Xanthine oxidase

Two carbon atoms and the nitrogen one of the imidazole fragment in purine base skeleton are got from only one amino acid in the de novo synthesis. Name it:

A. Glutamic acid

B. Asparagine

C. Folic acid

D. Aspartic acid

*E. Glycine

The terminal product of purine nucleotides catabolic pathways in humans is:

A. Beta-alanine

B. Oxaloacetate

*C. Uric acid

D. Beta-aminoisobutyric acid

E. Pyruvate

Which of the following is an example of a reverse transcriptase?

A. RNA Polymerase

B. Gyrase

C. Helicase

*D. Telomerase

E. DNA Polymerase

Restriction enzymes which have revolutionized the field of genetic engineering have been found in:

A. Animals

B. Viruses

C. Humans

*D. Bacteria

E. Plants

During replication of DNA, which one of the following enzymes produces the Okazaki fragments?

*A. DNA Polymerase III

B. DNA Polymerase I

C. DNA Polymerase II

D. RNA Polymerase II

E. RNA Polymerase I

Okazaki fragment is:

A. RNA fragment

B. RNA fragment with DNA head

C. None

*D. DNA fragment with RNA head

E. DNA fragment

DNA without introns is:

A. B DNA

B. Nuclear DNA

C. C DNA

*D. Mitochondrial DNA

E. Z DNA

Choose the inhibitor of DNA synthesis from following list:

A. Polymyxins

B. Chloramphenicol

C. Tetracycline

D. Penicillin

*E. Actinomycin

Excessive ultraviolet radiation is harmful to life. The damage caused to the biological systems by ultraviolet radiation is by:

A. Deamination of DNA

*B. Formation of thymidine dimmers

C. Ionization

D. Inhibition of DNA synthesis

E. DNA fragmentation

The sigma subunit of prokaryotic RNA polymerase:

A. Specifically recognizes the operator site

B. Binds the antibiotic rifampicin

C. Is part of the core enzyme

*D. Specifically recognizes the promoter site

E. Is inhibited by Alpha-amanitin

Replication and transcription are similar processes mechanistic terms because both:

A. Are semi conserved events

*B. Involve phosphodiester bond formation with elongation occurring in the 5’-3’ direction

C. Use RNA primers for initiation

D. Use deoxyribonucleotides as precursors

E. Use DNA polymerase III

Which of the following step is not a part of Polymerase Chain Reaction:

A. Chain extension by DNA polymerase and deoxyribonucleoside

B. Denature of DNA

*C. Use of restriction endonucleases which leave double stranded DNA

D. Primer construction

E. Use of restriction endonucleases which leave single stranded DNA

Okazaki fragments are formed during the synthesis of:

A. rRNA

B. mRNA

*C. Legging strand of DNA

D. tRNA

E. Leading strand of DNA