Biochemistry: Enzymes and Glycolysis

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Questions and Answers

What is the primary role of an enzyme in a chemical reaction?

To decrease the activation energy needed for the reaction. (correct)

To be consumed in the reaction.

To increase the activation energy required for the reaction.

To alter the equilibrium of the reaction.

Which statement best describes the specificity of enzymes?

Enzymes increase reaction rate randomly.

Enzymes catalyze only specific types of reactions and use specific substrates or chemically related molecules. (correct)

Enzymes catalyze a wide range of reactions, using any substrate.

Enzymes generally affect the equilibrium of the reaction.

If an enzyme is classified as a 'hydrolase', what type of reaction does it most likely catalyze?

The breaking of bonds using water. (correct)

Oxidation-reduction reactions.

The formation of bonds by condensation.

The transfer of functional groups from one molecule to another.

What distinguishes a catalyst from other substances involved in a chemical reaction?

It increases the reaction rate without being consumed. Signup and view all the answers

Which of the following accurately describes the efficiency of enzyme-catalyzed reactions compared to uncatalyzed reactions?

Enzyme-catalyzed reactions are typically $10^3$ to $10^8$ times faster. Signup and view all the answers

What is the role of activation energy in a chemical reaction?

It is the energy barrier that needs to be overcome for reactants to form products. Signup and view all the answers

If an enzyme's EC number is 2.4.1.11, what class does this enzyme belong to?

Transferases Signup and view all the answers

What distinguishes a ribozyme from a typical enzyme?

Ribozymes are made of RNA, whereas typical enzymes are usually made of protein. Signup and view all the answers

The catalytically active form of an enzyme is known as:

Holoenzyme Signup and view all the answers

What does the Michaelis constant (Km) reflect regarding enzyme activity?

The enzyme's affinity for its substrate Signup and view all the answers

Which of the following factors does NOT directly affect enzyme activity?

Product concentration Signup and view all the answers

An enzyme shows maximum activity at its:

Optimum temperature and pH Signup and view all the answers

What is the relationship between substrate concentration and reaction rate in the graph presented?

Reaction rate initially increases before leveling off with increased substrate concentration. Signup and view all the answers

A substance that reduces the velocity of an enzyme-catalyzed reaction is categorized as:

An inhibitor Signup and view all the answers

A unit of enzyme activity is the:

amount of enzyme activity that changes 1 µmol substrate in 1 minute under optimal conditions Signup and view all the answers

What distinguishes reversible inhibition from irreversible inhibition?

Reversible inhibitors bind to the enzyme temporarily, while irreversible inhibitors bind permanently. Signup and view all the answers

Study Notes

Learning Objectives

Describe enzymes and their common properties
List the enzyme classifications in correct order
Describe the factors that change enzyme activity
Explain the relationship between Km and activity
Explain enzyme inhibition and inhibition types

Metabolic Reactions

Enzymes facilitate biochemical reactions
Enzymes speed up reactions by lowering the activation energy
Enzymes are not consumed during a reaction
Enzymes change substrates by binding to them

Glycolysis

Glycolysis is a metabolic pathway
Enzymes are used in each reaction of glycolysis
Glycolysis is a series of enzymatic reactions
Glucose is converted to pyruvate

Activation Energy

Activation energy is the minimum energy required to start a chemical reaction.
Enzymes lower the activation energy necessary
Reactions proceed faster with lower activation energy

Activation Energy and Catalysts

Catalysts increase reaction rates by lowering activation energy
Enzymes act as biological catalysts
Enzymes are not consumed during the reaction
Enzymes lower reaction energy

Enzymes

Enzymes are biocatalysts
Enzymes increase reaction rates
Enzymes are biological catalysts

Properties of Enzymes

Most enzymes are proteins
Ribozymes are catalytic RNA
Enzymes change reaction rate (efficiency)
Enzymes show substrate specificity

Efficiency

Enzyme-catalyzed reactions are highly efficient (10^3 to 10^8 times faster)
Carbonic anhydrase is a fast enzyme

Specificity

Reaction specificity: A given enzyme catalyzes a specific type of reaction
Substrate specificity: An enzyme uses specific molecules

Enzyme Nomenclature: Classification

Enzymes are classified based on the type of reaction they catalyze
Enzyme Commission (EC) Number is a unique identifier for each enzyme

Enzyme Kinetics and Km

Km reflects an enzyme's affinity for a substrate
Small Km = high affinity, Large Km = low affinity
Vmax is maximal reaction rate

Km, A Clinical Example

Km value depends on the gene
Example: alcohol dehydrogenase and aldehyde dehydrogenase

Regulation of Enzyme Activity

Enzyme activity is regulated by several factors
Enzyme amount, synthesis, and degradation affect activity
Enzyme modification, covalent, compartments, and isozymes affect activity

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Description

This quiz covers the fundamentals of enzymes, including their properties, classifications, and the factors that affect their activity. It delves into glycolysis as a metabolic pathway where enzymes play a crucial role in biochemical reactions. Understand activation energy and the significance of catalysts in these processes.