Enzymes and Catalysis Quiz
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Questions and Answers

What initiates enzyme catalysis in the process described?

  • The substrate entering the active site (correct)
  • The enzyme changing shape
  • The formation of product
  • The breaking of bonds

What is the role of the induced-fit mechanism in enzyme activity?

  • It breaks the substrate's bonds
  • It synthesizes new molecules
  • It changes the enzyme's shape for better binding (correct)
  • It allows the substrate to be released

Which reaction is an example of a decomposition reaction as described?

  • Galactose and glucose to lactose
  • Lactose to glucose and galactose (correct)
  • Glycogen to glucose
  • Glucose to glycogen

In the synthesis reaction described, what are the products formed?

<p>Glycogen from glucose (C)</p> Signup and view all the answers

What happens to the enzyme after the products are released?

<p>The enzyme remains unchanged and can catalyze another reaction (A)</p> Signup and view all the answers

What binds to the enzyme during the reaction process?

<p>Substrate (B)</p> Signup and view all the answers

During the enzyme-catalyzed reactions, what occurs when the enzyme changes shape?

<p>New bonds are formed between substrates (A)</p> Signup and view all the answers

Which enzyme is specifically involved in the digestion of lactose?

<p>Lactase (A)</p> Signup and view all the answers

What distinguishes catalyzed reactions from uncatalyzed reactions?

<p>Catalyzed reactions occur faster due to the presence of enzymes. (A)</p> Signup and view all the answers

What is the primary role of the active site of an enzyme?

<p>It permits only a single substrate to bind. (D)</p> Signup and view all the answers

In the context of enzyme activity, what is meant by 'enzyme-substrate complex'?

<p>A temporary association formed when a substrate binds to an enzyme. (A)</p> Signup and view all the answers

Which statement about enzymes is accurate?

<p>Most enzymes are globular proteins with a unique three-dimensional structure. (A), Enzymes can remain unchanged after a reaction and thus can be reused numerous times. (C)</p> Signup and view all the answers

What effect do enzymes typically have on activation energy?

<p>Enzymes decrease the activation energy required for reactions. (C)</p> Signup and view all the answers

What characterizes exergonic reactions?

<p>Reactants have more energy within their chemical bonds than products. (C)</p> Signup and view all the answers

Which statement is true about endergonic reactions?

<p>Reactants contain less energy than the products. (B)</p> Signup and view all the answers

During which type of reaction is energy typically released?

<p>Decomposition reactions. (B)</p> Signup and view all the answers

How does the potential energy change in endergonic reactions?

<p>Potential energy increases net throughout the reaction. (A)</p> Signup and view all the answers

If a reaction requires energy to proceed, what type of reaction is it likely to be?

<p>Endergonic reaction. (D)</p> Signup and view all the answers

Which process is classified as an exergonic reaction?

<p>Cellular respiration. (A)</p> Signup and view all the answers

What occurs to the energy released during an exergonic reaction as products are formed?

<p>It is lost as heat to the environment. (C)</p> Signup and view all the answers

Which of the following statements describes the energy flow in exergonic and endergonic reactions?

<p>Endergonic reactions absorb energy while exergonic reactions don't. (C)</p> Signup and view all the answers

What are the two main components of a chemical equation?

<p>Reactants and products (C)</p> Signup and view all the answers

In a balanced chemical equation, what condition must be met?

<p>Same number of each type of element on both sides (B)</p> Signup and view all the answers

What is a decomposition reaction?

<p>A reaction where a large molecule is broken down into smaller ones (C)</p> Signup and view all the answers

Which term refers to the collective term for all chemical reactions occurring in the body?

<p>Metabolism (A)</p> Signup and view all the answers

What characterizes a catabolic reaction?

<p>It is a breakdown reaction involving the release of energy (A)</p> Signup and view all the answers

What is the role of the arrow in a chemical equation?

<p>It indicates the direction of the reaction (D)</p> Signup and view all the answers

What distinguishes an anabolic reaction from a catabolic reaction?

<p>Anabolic reactions utilize energy while catabolic reactions release energy (D)</p> Signup and view all the answers

How can chemical reactions be classified based on changes in chemical energy?

<p>They can be classified as either endothermic or exothermic reactions (D)</p> Signup and view all the answers

What is the primary reason why heat is usually not available to do work?

<p>Heat represents kinetic energy associated with random motion. (D)</p> Signup and view all the answers

What does the first law of thermodynamics state?

<p>Energy can neither be created nor destroyed; it can only change in form. (A)</p> Signup and view all the answers

When energy is transformed, what happens to some of the energy according to the second law of thermodynamics?

<p>Some energy is lost as heat. (B)</p> Signup and view all the answers

Which of the following best describes metabolism?

<p>The collection of chemical reactions occurring in the body. (B)</p> Signup and view all the answers

Which example illustrates the conversion of energy as stated in the first law of thermodynamics?

<p>Chemical energy in food converting to electrical energy in brain cells. (C)</p> Signup and view all the answers

What often occurs in the human body as energy is converted from one form to another?

<p>Energy is lost in the form of heat. (B)</p> Signup and view all the answers

In the context of thermodynamics, which scenario best exemplifies the second law?

<p>A car using fuel converts chemical energy to mechanical energy, causing heat loss. (C)</p> Signup and view all the answers

How does the body's maintenance of homeostasis relate to energy conversion?

<p>It utilizes energy transformations to produce heat necessary to sustain biological functions. (B)</p> Signup and view all the answers

What is the primary substrate used in the process described?

<p>Glucose (B)</p> Signup and view all the answers

What is a likely consequence of severe increases in temperature on enzyme activity?

<p>Protein denaturation (C)</p> Signup and view all the answers

At what temperature range do human enzymes typically function best?

<p>95-104°F (C)</p> Signup and view all the answers

What happens to enzyme flexibility as temperature decreases?

<p>It becomes more rigid (D)</p> Signup and view all the answers

What could be a result of moderate fever on enzyme activity?

<p>Increased efficiency (D)</p> Signup and view all the answers

Which statement is true regarding the relationship between enzyme temperature and reaction rate?

<p>Optimal temperature maximizes enzyme activity until denaturation occurs. (B)</p> Signup and view all the answers

What is released as a product of the action of glycogen synthase?

<p>Glycogen (B)</p> Signup and view all the answers

What are weak intramolecular interactions responsible for in enzyme function?

<p>Stabilizing the active site (B)</p> Signup and view all the answers

Flashcards

Heat

The kinetic energy associated with the random movement of molecules within a substance. It is generally not usable for work.

Temperature

A measure of the average kinetic energy of the molecules within a substance.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another.

Second Law of Thermodynamics

During energy transformations, some energy is always lost as heat, reducing the amount of usable energy.

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Metabolism

The sum of all chemical reactions occurring within a living organism.

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Energy Conversion

The process of changing energy from one form to another.

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Homeostasis

The maintenance of a stable internal environment in a living organism.

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Usable Energy

Energy that can be used to do work.

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Chemical Reaction

A process that involves the breaking and forming of chemical bonds between atoms and molecules, resulting in the creation of new substances.

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Chemical Equation

A shorthand way to represent a chemical reaction, using symbols and numbers to show the reactants, products, and their proportions.

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Reactants

The substances that are present at the beginning of a chemical reaction and undergo transformation.

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Products

The substances that are formed as a result of a chemical reaction.

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Decomposition Reaction

A chemical reaction where a larger molecule is broken down into smaller molecules or atoms.

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Exergonic Reaction

A chemical reaction where the reactants have more energy than the products, resulting in a net release of energy. This typically involves breaking down complex molecules into simpler ones.

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Endergonic Reaction

A chemical reaction where the reactants have less energy than the products, requiring a net input of energy. This typically involves building up complex molecules from simpler ones.

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Potential Energy in Reactions

The amount of stored chemical energy within the bonds of molecules. Exergonic reactions release potential energy, while endergonic reactions require potential energy input.

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Energy Supplied/Released Graph

A visual representation of energy changes during a reaction. Exergonic reactions show a net release of energy as reactants are converted to products. Endergonic reactions show a net input of energy as products are formed.

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Reactants in Exergonic Reactions

The starting molecules in an exergonic reaction, containing more energy than the products.

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Products in Exergonic Reactions

The molecules formed in an exergonic reaction, having less energy than the reactants.

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Reactants in Endergonic Reactions

The starting molecules in an endergonic reaction, containing less energy than the products.

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Products in Endergonic Reactions

The molecules formed in an endergonic reaction, having more energy than the reactants.

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Catalyzed Reaction

A chemical reaction that is sped up by the presence of an enzyme.

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Uncatalyzed Reaction

A chemical reaction that proceeds without the assistance of an enzyme.

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Enzyme-Substrate Complex

A temporary structure formed when an enzyme binds to its specific substrate, bringing the reactants together for the chemical reaction to occur.

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Active Site

The specific region on an enzyme where the substrate binds and the chemical reaction takes place.

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Specificity of Shape

The unique three-dimensional shape of an enzyme's active site that allows it to bind to only one specific substrate.

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Induced Fit

The change in shape of an enzyme's active site to better fit the substrate molecule, leading to an optimal chemical reaction.

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Catalysis

The process by which an enzyme speeds up a chemical reaction without being consumed in the process.

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Synthesis Reaction

A chemical reaction where smaller molecules are combined to form a larger molecule.

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Substrate

The specific molecule that an enzyme acts upon to catalyze a chemical reaction.

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Effect of Temperature on Enzymes

Enzymes have an optimal temperature range for activity. Human enzymes function best at body temperature, with moderate fever slightly increasing their efficiency. High temperatures can denature enzymes, causing them to lose their shape and function.

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Enzyme Denaturation

The loss of an enzyme's three-dimensional shape, caused by extreme temperatures or pH changes, leading to loss of function.

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Enzyme Optimal Temperature

The temperature at which an enzyme exhibits its highest activity. For human enzymes, this is typically around body temperature.

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Effect of pH on Enzymes

Enzymes have a specific pH range at which they function optimally. Changes in pH can disrupt the three-dimensional structure of enzymes, affecting their catalytic activity.

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Product of an Enzymatic Reaction

The new molecule produced as a result of an enzyme's activity on its substrate.

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Enzyme Specificity

Enzymes are highly specific, meaning they catalyze only a particular type of reaction involving a specific substrate. Think of each enzyme as a lock with a specific key (substrate).

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Glycogen Synthetase

An enzyme that builds up glycogen from glucose monomers, the building blocks of glycogen. Once the glycogen is formed, the enzyme is released to work on other substrates.

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Study Notes

Energy, Chemical Reactions, and Cellular Respiration

  • Living organisms need energy for various functions, including powering muscles, pumping blood, absorbing nutrients, exchanging gases, synthesizing molecules, and establishing cellular ion concentrations.
  • Glucose is broken down through metabolic pathways to form ATP, the cell's energy currency.

Energy: States of Energy

  • Energy is the capacity to do work. It exists in two fundamental states:
    • Potential energy: Stored energy, related to position.
    • Kinetic energy: Energy of motion.
  • Energy is convertible between potential and kinetic forms. (E.g., water at the top of a dam possesses potential energy; its movement downstream has kinetic energy.)
  • A concentration gradient across a plasma membrane stores potential energy. Sodium ions concentrated outside a cell hold potential energy. Their movement into the cell releases that energy.

Potential Energy and the Plasma Membrane

  • Sodium ion concentration gradient across the plasma membrane of a cell.
  • The sodium ions outside the cell have potential energy. (analogous to water at the top of a dam)
  • The movement of sodium ions from high concentration outside the cell to a lower concentration inside the cell releases kinetic energy.
  • This movement can be harnessed to do cellular work.

Energy: Forms of Energy

  • Chemical Energy (A Form of Potential Energy):

    • Stored in a molecule's chemical bonds.
    • Crucial for cellular processes (movement, synthesis, gradients).
    • Released during bond breaking.
    • Triglycerides are for long-term energy storage in adipose tissue.
    • Glycogen is stored in liver and muscle.
    • ATP is stored and used immediately in all cells.
    • Protein can be a fuel source, but it has more critical functions.

  • Kinetic Energy Forms:

    • Electric energy: Movement of charged particles (e.g., nerve impulses, ion movement across membranes).
    • Mechanical energy: Energy of motion in objects/structures (e.g., muscle contraction).
    • Sound energy: Compression and vibration of molecules, (e.g., eardrum vibration).
    • Radiant energy: Energy of electromagnetic waves (e.g., visible light for vision, UV radiation). Higher frequency light carries more energy. This energy can damage DNA.
    • Heat: Kinetic energy of random molecular motion. Typically unusable for work in biological systems.

Energy: Laws of Thermodynamics

  • First Law: Energy cannot be created or destroyed, only changed in form.
  • Second Law: When energy changes forms, some energy is lost as heat; usable energy decreases, with every transformation.

Chemical Reactions: Chemical Equations

  • Metabolism: Collective term for all chemical reactions in the body.
  • Chemical reactions: Occur when chemical bonds in molecules break and new bonds form. These changes are summarized in chemical equations.

Chemical Reactions: Classification of Chemical Reactions

  • Classification Based on Changes in Chemical Structure:
    • Catabolism: Breakdown of complex molecules to simpler ones.
    • Anabolism: Building complex molecules from simpler ones.
  • Classification Based on Changes in Chemical Energy:
    • Exergonic reactions: Release more energy than they require; decomposition reactions.
    • Endergonic reactions: Absorb more energy than they release; synthesis reactions.
  • ATP cycling: Continuous formation and breakdown of ATP, the cell's primary energy currency.

Enzymes

  • Function: Biological catalysts that accelerate chemical reactions by lowering activation energy without being consumed in the reaction.
  • Mechanism of action: Substrate binds to the enzyme's active site, forming an enzyme-substrate complex. Induced-fit: shape change in the active site stresses existing chemical bonds, allowing new bonds to form. Products are released and the enzyme is ready for another reaction.

Enzymes: Structure and Location

  • Enzymes are largely globular proteins.
  • The active site is a specific region in the enzyme, allowing only a target substrate shape to bind. This site permits a highly controlled chemical reaction.

Enzymes: Temperature

  • Optimal temperature for enzymes that function in the human body is moderate (95-104°F), slightly above the average body temperature.
  • Higher temperatures can denature proteins, which alters the enzyme's critical shape.

Enzymes: pH

  • Enzymes function best in a narrow pH range.
  • Changes in pH can denature proteins, affecting the functioning of the enzyme.
  • Optimal pH might vary depending on location within the body (e.g., stomach).

Clinical View: Lactose Intolerance

  • Caused by a deficiency in the enzyme lactase, which is needed to break down the disaccharide lactose into simpler sugars (glucose and galactose).
  • Symptoms often include abdominal upset.
  • Treatment involves avoiding milk or using lactase enzymes to digest lactose.

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Description

Test your knowledge on enzyme catalysis and the mechanisms involved. This quiz covers key concepts like the induced-fit mechanism, reaction types, and the fate of enzymes after product release. Challenge yourself and deepen your understanding of enzymatic reactions.

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