Biochemistry Enzymes and Cofactors Quiz

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Questions and Answers

Which of the following properties is characteristic of acid phosphatase?

Insensitivity to pH (correct)

High catalytic activity

Thermally unstable

Changeability after completion of the reaction

What accurately describes the allosteric center of an enzyme?

A site for substrate attachment

A site for binding substances differing from substrates (correct)

A section for ionizing the enzyme

A non-protein part that stabilizes the enzyme

Which statement accurately defines enzyme inhibitors?

Substances that promote enzymatic reactions

Agents that accelerate enzymatic activity

Compounds that denature enzymes.

Substances that decrease the rate of enzymatic reactions (correct)

Which vitamin functions as a coenzyme accepting and donating electrons along the pyrimidine ring?

Vitamin PP Signup and view all the answers

What is the active form of the vitamin involved in aminotransferase?

Pyridoxal phosphate Signup and view all the answers

Which interaction best describes the role of vitamins as cofactors in enzymatic reactions?

They bind only through weak interactions. Signup and view all the answers

A derivative of vitamin PP is predominantly involved in which type of biochemical reaction?

Dehydrogenation reactions Signup and view all the answers

Catabolism is primarily characterized by which of the following processes?

Breakdown of molecules with energy release Signup and view all the answers

What is the product of the specific pathway of monosaccharide catabolism?

Pyruvate Signup and view all the answers

Which steps refer to the common pathway of catabolism?

Oxidative decarboxylation of pyruvate and the Krebs cycle Signup and view all the answers

What is the main product produced alongside NADPH2 in the pentose phosphate pathway?

Ribose-5-phosphate Signup and view all the answers

Which enzyme is primarily responsible for the formation of NADPH2 in the pentose phosphate pathway?

Glucose-6-phosphate dehydrogenase Signup and view all the answers

What is the central intermediate metabolite of protein, lipid, and carbohydrate metabolism?

Acetyl-CoA Signup and view all the answers

Which substance is synthesized using NADPH2 as a hydrogen donor?

Cholesterol Signup and view all the answers

What does a substrate phosphorylation reaction involve?

ATP synthesis using high-energy bonds of substrates Signup and view all the answers

What is the significance of the pentose phosphate cycle in cellular metabolism?

It generates pentose sugars and NADPH2 Signup and view all the answers

Who is the primary electron acceptor of the respiratory chain?

FAD Signup and view all the answers

What product is formed during the oxidative phase of the pentose phosphate pathway?

Ribulose-5-phosphate Signup and view all the answers

What is the mechanism of action of the first complex of the respiratory chain?

Transfers electrons from NADH to coenzyme Q Signup and view all the answers

Which product of the pentose phosphate pathway is essential for the synthesis of nucleic acids?

Ribose-5-phosphate Signup and view all the answers

What is the final electron acceptor in the respiratory chain?

Oxygen Signup and view all the answers

Which of the following is synthesized as a result of the non-oxidative stage of the pentose phosphate pathway?

Glyceraldehyde-3-phosphate Signup and view all the answers

What is the correct sequence of components in the respiratory chain?

NAD, FMN, ubiquinone, cytochrome b, cytochrome c1, cytochrome c, cytochrome a3 Signup and view all the answers

Which pentose phosphate pathway products are necessary for gluconeogenesis?

Glyceraldehyde-3-phosphate and fructose-6-phosphate Signup and view all the answers

What is the function of histamine in the body?

Stimulates the secretion of gastric juice Signup and view all the answers

Which of the following is a way that dopamine can be inactivated?

Oxidation by MAO enzymes Signup and view all the answers

Which of the following is an intermediate carrier of one-carbon groups?

H4-folate Signup and view all the answers

Which reaction leads to the reduction of NADP?

Oxidative stage of the pentose phosphate cycle Signup and view all the answers

What is the amino acid precursor of porphyrins?

Glycine Signup and view all the answers

What is the regulatory enzyme of the pentose phosphate pathway?

Glucose-6-phosphate dehydrogenase Signup and view all the answers

What is the active form of methionine that is synthesized from methionine and ATP?

S-adenosylmethionine Signup and view all the answers

In the synthesis of cysteine, which molecule is the donor of the sulfur atom?

Methionine Signup and view all the answers

Which substance serves as the primary substrate for the pentose phosphate cycle?

Glucose-6-phosphate Signup and view all the answers

What condition results from a defect in phenylalanine hydroxylase in the metabolism of phenylalanine?

Phenylketonuria Signup and view all the answers

Which of the following substances are primary substrates of gluconeogenesis?

Lactate, amino acids, glycerol Signup and view all the answers

Which enzyme catalyzes the reaction converting oxaloacetate to phosphoenolpyruvate?

Phosphoenolpyruvate carboxykinase Signup and view all the answers

Which compound is capable of transferring a methyl group to other compounds?

Methylene H4-folate Signup and view all the answers

What is the fate of lactate during intense muscle work?

Involved in gluconeogenesis in the liver Signup and view all the answers

Which conversion reflects a specific enzymatic reaction of gluconeogenesis?

Glucose-6-phosphate to glucose Signup and view all the answers

What process links the glucose-lactate cycle with gluconeogenesis?

Formation of lactate in muscles and its entry into hepatocytes Signup and view all the answers

Which organ is most sensitive to hypoglycemia during prolonged fasting?

Brain Signup and view all the answers

What is the final product of glycogen breakdown in muscles?

Glucose 6-phosphate Signup and view all the answers

Which enzyme, when congenitally deficient, leads to hypoglycemia in glycogenosis?

Glycogen phosphorylase Signup and view all the answers

What hormone stimulates glycogen mobilization in the liver?

Adrenaline Signup and view all the answers

What is the role of glucose 6-phosphatase in the liver?

Maintain blood glucose levels Signup and view all the answers

Which of the following reactions involves transaldolase?

Formation of erythrose-4-phosphate and fructose-6-phosphate Signup and view all the answers

What effect does insulin have on beta-oxidation of fatty acids?

Inhibition Signup and view all the answers

What type of bond is primarily found in the linear regions of glycogen molecules?

Alpha-1,4-glycosidic Signup and view all the answers

Study Notes

Biochemistry Metabolism Module

Proteolytic enzymes act on proteins, carbohydrates, vitamins, lipids, and nucleic acids.
Substrate binding to the active site of the enzyme follows the principle of complementarity.
Enzymes catalyzing intramolecular transfer of atoms or groups are called transferases, ligases, isomerases, hydrolases, and oxidoreductases.
Pepsin's conversion from an inactive to an active form involves partial proteolysis, a decrease in molecular weight.
An enzyme containing a coenzyme and having enzymatic activity is a holoenzyme. Coenzymes are organic molecules, and cofactors are inorganic ones.

Other Enzyme Information

Kinases catalyze the transfer of phosphate groups.
Enzymes are often studied in biological fluids like serum, gastric juice, cerebrospinal fluid, lymph, and saliva.
The catalytic center of an enzyme directly participates in the reaction.
The active center of an enzyme is where the substrate attaches.
Irreversible inhibitors form covalent bonds with the enzyme.
In liver problems, ALT and AST levels change.
Oxidative decarboxylation of keto acids involves a thiamine derivative.
Vitamins like PP, A, B2, B6, and B7 perform coenzyme roles, carrying electrons and protons.
Pyridoxal phosphate is the active form of vitamin B6 for aminotransferase.
ATP synthesis in muscle occurs through various enzymatic pathways like aerobic glycolysis, anaerobic glycolysis, lactate formation/oxidation, and oxidative phosphorylation of glyceraldehyde-3-phosphate.
The pentose phosphate pathway produces NADPH2 and ribose-5-phosphate for nucleotide synthesis.
Key enzymes in glycolysis, like phosphofructokinase and pyruvate kinase, regulate the process.
Anabolism builds complex molecules, while catabolism breaks them down, releasing energy.
Lactate and pyruvate are important metabolic intermediates.
Key enzymes in the Krebs cycle include isocitrate and alpha-ketoglutarate related to decarboxylation.
Acetyl-CoA is a crucial intermediate metabolite for protein, carbohydrate, and lipid metabolism.
Various vitamins (A, B vitamins, PP) serve as coenzymes.
Many enzymes are used as biomarkers for various bodily conditions like liver damage.
In conditions of oxygen shortage, energy production utilizes anaerobic glycolysis.
For accurate diagnosis of diseases, enzyme activity is measured in biological fluids.
Enzymes are essential parts of cellular function in metabolism, and they can help be biomarkers for diseases.

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Description

Test your knowledge on the properties of enzymes, cofactors, and the functions of vitamins in biochemical reactions. This quiz covers key concepts related to acid phosphatase, enzyme inhibitors, and metabolic pathways. Perfect for students studying biochemistry and related fields.