Enzymes: structure, mechanism of action and regulation of activity. Energy metabolism

Tests from licensed examination “Krok-1” proposed in 2005-2015 years

Simple & Conjugated Proteins: structure, properties, function.

Enzymes: structure, mechanism of action and regulation of activity. Energy metabolism

1. Succinate dehydrogenase catalyses the dehydrogenation of succinate. Malonic acid HOOC-CH2-COOH is used to interrupt the action of this enzyme. Choose the inhibition type:

A. Allosteric

B. *Competitive

C. Non-competitive

D. Dephosphorylation

E. Limited proteolysis

2. The conjugated protein necessarily contains special component as a non­protein part. Choose the substance that can't carry out this function:

A. Glucose

B. *HNO₃

C. Thiamine pyrophosphate

D. ATP

E. AMP

3. Only one factor can influence the charge of amino acid radicals in the active centre of enzyme. Name this factor:

B. The presence of a competitive inhibitor

C. Temperature

D. Pressure

E. *pH medium

F. The surplus of a product

4. Researchers isolated five isozymes of Lactate dehydrogenase from human blood serum and studied their properties. What property of these isozymes indicates that they are genetic forms of the same enzyme?

A. They have the same molecular weight

B. They catalyze the same reaction*

C. The same tissue localization

D. The same electrophoretic mobility

E. The same net charge of the molecule

5. Different functional groups can be presented in the structure of L-amino aci­d radicals. Identify the group that is able to form ester bond:

A. *-OH

B. -CONH2

C. -SH

D. -NH2

E. -CH3

6. Toxic affection of liver results in dysfunction of protein synthesis. It is usually accompanied by the following kind of dysproteinemia:

A Absolute hypoproteinemia

B Relative hypoproteinemia

C Absolute hyperproteinemia

D Relative hyperproteinemia

E Paraproteinemia

7. In case of enterobiasis acrihine - the structural analogue of vitamin B2 - is administered. The synthesis disorder of which enzymes does this medicine cause in microorganisms?

A FAD-dependent dehydrogenases

B Cytochromeoxidases

C Peptidases

D NAD-dependet dehydrogenases

E. Aminotransferases

8. In clinical practice tuberculosis is treated with izoniazid preparation – that is an anti-vitamin able to penetrate into the tuberculosis bacillus. Tuberculostatic effect is induced by the interference with replication processes and oxidation-reduction reactions due to the buildup of pseudo-coenzyme:

A. FMN

B. NAD

C. CoQ

D. FAD

E. TDP

9.Profuse foam appeared when dentist put hydrogen peroxide on the mucous of the oral cavity.

What enzyme caused such activity?

A Catalase

B Cholinesterase

C Acetyltransferase

D Glucose-6-phosphatdehydrogenase

E Methemoglobinreductase

10.Twelve hours after an accute attack of retrosternal pain a patient presented a jump of aspartate aminotransferase activity in blood serum. What pathology is this deviation typical for?

A Myocardium infarction

B Viral hepatitis

C Collagenosis

D Diabetes mellitus

E Diabetes insipidus

11. Marked increase of activity of МВ-forms of CPK (creatine phosphokinase) and LDH-1 were revealed on the examination of the patient's blood. What is the most likely pathology?

A Miocardial infarction

B Hepatitis

C Rheumatism

D Pancreatitis

E Cholecystitis

12. A patient presents high activity of LDH1, LDH2, aspartate aminotransferase, creatine phosphokinase. In what organ (organs) is the development of a pathological process the most probable?

A In the heart muscle (initial stage of myocardium infarction)

B In skeletal muscles (dystrophy, atrophy)

C In kidneys and adrenals

D In connective tissue

E In liver and kidneys

13. During metabolic process active forms of the oxygen including superoxide anion radical are formed in the human body. With help of what enzyme is this anion inactivated?

A Superoxide dismutase

B Catalase

C Peroxidase

D Glutathione peroxidase

E Glutathione reductase

14. 6 hours after the myocardial infarction a patient was found to have elevated level of lactate dehydrogenase in blood. What isozyme should be expected in this case?

1. LDH₄
2. LDH₁*
3. LDH₅
4. LDH₃
5. LDH₂

15.

Those organisms which in the process of evolution failed the protection from H₂O₂ can exist only in anaerobic conditions. Which of the following enzymes can break hydrogen peroxide down?

Oxygenase and hydroxylase

Oxygenase and catalase

Cytochrome oxidase, cytochrome b5

Flavin-dependent oxidase

*Peroxidase and catalase

16. Cyanide is a poison that causes instant death of the organism. What enzymes found in mitochondria are affected by cyanide?

Flavin enzymes

*Cytochrome oxidase (aa3)

Cytochrome B5

NAD+- dependent dehydrogenase

Cytochrome P-450

17. A patient is diagnosed with cardiac infarction. Blood test for cardio-specific enzymes activity was performed. Which of enzymes has three isoforms?

Creatine kinase*

Aspartate transaminase

Alanine transaminase

Lactate dehydrogenase

Pyruvate kinase

Date: 2016-04-22; view: 1526