Enzymes: Turnover Number and Selectivity

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What is the term used to describe the number of substrate molecules converted to product per enzyme?

Enzyme activity

Reaction rate

Catalytic efficiency

Turnover number (correct)

Which of the following statements about enzyme selectivity is true?

Enzymes can catalyze multiple types of chemical reactions

Enzyme selectivity depends on the concentration of the substrate

Enzymes are not selective and can act on any substrate

Enzymes interact with one or more substrates and catalyze only one type of chemical reaction (correct)

Which of the following statements about enzymes is incorrect?

Measurement of enzyme activities is used in the diagnosis and monitoring of diseases

Enzymes undergo qualitative and quantitative changes before and after the reaction (correct)

Enzymes are localized in specific organelles within the cell

Enzymes are involved in various cellular processes such as glycolysis and fatty acid synthesis

In which organelle does the TCA cycle take place?

Mitochondria Signup and view all the answers

Which of the following processes occurs in the cytosol?

Both b and c Signup and view all the answers

Which enzyme deficiency is associated with the hereditary metabolic disease galactosemia?

Galactose-1-phosphate uridyl transferase Signup and view all the answers

What type of bonds do reversible inhibitors form with enzymes?

Hydrogen bonds Signup and view all the answers

Which enzyme regulation mechanism involves the phosphorylation of a serine residue?

Covalent modification Signup and view all the answers

In what form are some enzymes initially synthesized before being activated?

Inactive precursors Signup and view all the answers

Which type of plasma enzymes have diagnostic importance in tissue or organ diseases?

Non-specific enzymes for plasma Signup and view all the answers

What is the primary function of enzymes related to the chylomicron mechanism in plasma?

Chylomicron metabolism Signup and view all the answers

What distinguishes irreversible inhibitors from reversible ones in terms of enzyme binding?

They modify the enzyme covalently Signup and view all the answers

Which model describes the enzyme as a rigid structure that only binds to substrates with a complementary shape?

Lock and key model Signup and view all the answers

What is the term used for enzymes that are initially synthesized in an inactive form and become active later when they reach their functional location?

Zymogens Signup and view all the answers

Which part of a compound enzyme is responsible for its catalytic activity?

The protein component Signup and view all the answers

What is the term used for different variants of the same enzyme that catalyze the same reaction but have different physicochemical properties?

Isoenzymes Signup and view all the answers

According to the induced fit model, what happens when a substrate binds to an enzyme?

Both the enzyme and the substrate undergo conformational changes to fit each other. Signup and view all the answers

Which of the following statements about proton transfer is true?

It is the most common reaction in biochemistry. Signup and view all the answers

What is the role of water in specific acid-base catalysis?

Water acts as a proton donor or acceptor. Signup and view all the answers

Which type of enzymes are composed solely of protein?

Simple enzymes Signup and view all the answers

In general acid-base catalysis, what serves as the proton donor or acceptor?

The amino acid side chains in the enzyme's active site. Signup and view all the answers

How does the speed of a reaction increase due to general acid-base catalysis?

From 10^2 to 10^5 times faster. Signup and view all the answers

Which of the following amino acid residues is NOT involved in covalent catalysis?

Alanine Signup and view all the answers

In the catalysis of chymotrypsin, what is the role of water?

Water does not directly catalyze the peptide bond. Signup and view all the answers

Which of the following is NOT one of the 11 important serum enzymes in clinical diagnosis mentioned in the text?

Alanine aminotransferase (ALT) Signup and view all the answers

What is the name of the energy barrier that separates the reacting molecules and products in a chemical reaction?

Free activation energy Signup and view all the answers

What is the main purpose of measuring enzyme activity?

To determine the amount of substrate lost or transformed Signup and view all the answers

Which two factors are important to consider when choosing a method for enzyme activity determination?

The practicality of the method and its sensitivity Signup and view all the answers

What is the name of the two-step process that describes the mechanism of action of enzymes?

Energy changes and chemistry of the active site Signup and view all the answers